Potato psyllids (Bactericera cockerelli) are disease-carrying, life-sucking plant lice. These invasive pests also feed on tomatoes and other members of the nightshade family, along with several other garden plants.
Potato psyllid description
Potato psyllids are tiny. When I say tiny, I mean that an adult potato psyllid could stretch out comfortably across the edge of an American nickel, without dangling. If you get close enough, preferably with a hand lens or magnifying glass, you would see that they look like miniature cicadas. Potato psyllid adults are black, with a white band across the first abdominal segment and an inverted “V” on the final segment. They have clear wings that are held roof-like over the body when not flying or jumping. [They jump a lot.]
Potato psyllid lifecycle
Potato psyllids start out as eggs. Each female lays approximately 200 eggs, each of which hatches in 6 to 10 days. Those eggs look like microscopic footballs held to the underside of leaves with short stalks. [Do not mistake those short-stalked eggs to the longer stalked, beneficial lacewing eggs.]
After those eggs hatch into green, fringed nymphs, they look more like whiteflies or soft scale insects. Then, they go through five developmental stages, also known as molts or instars. Under ideal conditions, all that growing can be completed in less than two weeks.
Damage caused by potato psyllids
If sucking nutrient rich plant fluids wasn’t problem enough, potato psyllids cause other problems, too. For one thing, as nymphs feed, they release a toxin that can kill young transplants. This toxin also causes upward curling of leaflets closest to the stem on the upper portions of the plant. This condition is known as “psyllid yellows” or “vein greening”. The characteristic yellowing usually starts along leaf margins and then moves inward, turning purple in some cases. As this condition worsens, nodes [bumps where leaves emerge] become enlarged and closer together, rosetted clusters of leaves emerge from axillary (or lateral) buds, and aerial tubers begin to form. Aerial tubers grow at the end of aboveground stems, as opposed to underground stems, the way proper potatoes grow. When this pest feeds on tomato plants, it can cause no fruit production or overproduction of poor quality fruits.
Eventually, the once green, bushy potato plant looks more like a pitiful yellow Christmas tree. [If chlorosis is spotty and leaf rosetting is not present, the problem is more likely to be calico virus.] If potato psyllids are removed from the plant, the condition will stop progressing.
Potato psyllids are also carriers of another condition, known as zebra chip. Zebra chip is a bacterial disease that causes potatoes to store sugar, rather than starch. That might sound like a great idea for a new dessert food, but the presence of sugars cause ugly brown lines across the length of the potato. When cooked, these brown lines turn black, hence the name. This condition reduces crop size by 20 to 50%. Healthy appearing potatoes from plants affected by zebra chip are more likely to sprout while in storage.
Managing potato psyllids
You can’t control potato psyllids if you don’t know where they are. The first step to managing potato psyllids is to use yellow sticky traps. You can buy these at any garden center, or you can make your own with some yellow paperboard and sticky barrier goo. You should also inspect the undersides of leaves, looking for nymphs. While you’re at it, you should probably check the underside of any nearby bean or pepper plants, as these may also become infested.
In commercially grown potato fields, where potato psyllid is known to occur, a type of systemic neonicotinoid neurotoxin, called imidacloprid, is applied. [While not yet noted in California, resistance to imidacloprid has been documented in Texas.] Organic growers, like myself, use spinosad.
Because potato psyllids are not native to California, our local team of predators, which include lady beetles, lacewing larvae, and minute pirate bugs, have not been very effective at controlling this pest. Not yet, anyway.
Aphids on potatoes? Well, why not? They’re on everything else!
Potatoes are susceptible to two different types of aphids: green peach aphids and potato aphids. Today, we will learn about potato aphids.
Originally from North America, these pests are now found everywhere potatoes are grown. And potatoes are not their only food of choice. Your cabbages, tomatoes, eggplant, peaches, and peppers are also at risk, along with many other food crops.
Potato aphid description
Potato aphids (Macrosiphum euphorbiae) can be either green or pink, with a dark dorsal stripe, and they tend to be larger, with longer legs, than most other aphid species. When feeding on tomatoes, potato aphids become distinctly red. They have the same long-legged, soft, pear-shaped wingless body of other aphids. As populations boom, or food becomes otherwise scarce, some aphids will develop wings with which to fly to new feeding grounds.
Potato aphid lifecycle
Potato aphids, like other aphids, are phenomenally prolific. A single female aphid can produce 600 billion descendants in a single season. Aphids reproduce both sexually and asexually. When females produce offspring without male intervention (parthenogenesis), the offspring are born live and significantly smaller than their co-authored siblings. When reproduction involves a male counterpart, offspring are laid as eggs that overwinter in nearby weeds, or on other host plants. Adult aphids molt four times, leaving behind telltale white skins.
Damage caused by potato aphids
Aphid feeding is usually first seen as deformed leaves. As aphids feed, they damage plant tissue and disrupt the balance of growth hormones. This can reduce or eliminate crop size, and it can kill young plants. These sap sucking pests tend to cluster together, piercing plant tissue and sucking out nutrient rich fluids. They also poop out sugary honeydew, which attracts protective, disease-carrying ants, and creates habitat for sooty mold.
Potato aphid feeding can certainly weaken plants, but the real problem is that these aphids carry and transmit a number of viral diseases, such as cucumber mosaic, lettuce mosaic, bearded iris mosaic, narcissus yellow stripe virus, tulip breaking virus, potato virus Y, beet mild yellowing virus, beet yellows virus, alfalfa mosaic, and potato leafroll disease. Plants infected with potato leafroll disease will produce potatoes with a network of browning phloem tissue, called net necrosis, that is very unappetizing. Once a potato plant is infected with leafroll, it and three plants in all directions should be removed to prevent further spread of the disease.
Controlling potato aphids
The battle against aphids in the garden never ends. It starts by monitoring plants regularly for signs of infestation. Potato aphids tend to prefer the lower portions of plants, the undersides of leaves, and around new buds. You can dislodge aphids with a powerful stream of water from the garden hose, but it is practically impossible to get every single aphid off your potato plants in this way, and it only takes one aphid to start the whole process over again. Insecticidal soaps can be used with better results, but you have to make sure you wet every surface of the plant. Personally, I wipe them off whenever I see them. I like to think it slows them down a little, if nothing else.
The next step in controlling potato aphids is to remove nearby plants that might harbor these pests. This means keeping weeds away from potato patch. Malva, penny cress, and various mustards, in particular, can act as early season host plants for this pest.
Luckily, lady beetles, lacewings, syrphid or hoverfly larvae, and parasitic wasps will all help control potato aphid populations. That’s assuming you haven’t used broad spectrum pesticides and wiped out your helpers.
What's eating your potatoes?
Not counting gardeners, there are several types of mammals that may turn up in your garden. Some can be helpful, others can be a royal pain.
Mammals are warm-blooded and more or less intelligent. This can make excluding them from certain areas of the garden problematic. In most cases, there are ways to work around pesky mammals in the garden, without losing your mind or getting in trouble with local law enforcement.
Speaking of law enforcement, before you go trapping, shooting, poisoning, or otherwise dispatching wildlife, you need to track down your local laws and obey them. The low level squirrel feud can turn into a legal nightmare if improper methods are used against them. It’s not worth it - regardless of how tempting it may be when they take your last juicy pears for the umpteenth time!
So, let’s see which animals might end up in the garden and how to protect your plants against them.
There are three major types of bats found in North America: leaf-nosed bats, vesper bats, and free-tailed bats. These bats are primarily insectivores, capturing insect pests, such as moths, wasps, flies, mosquitoes, in flight, or capturing beetles, ants, and other insects off of leaves or from the ground. This makes bats welcome guests in the garden, though they will sometimes eat ripe fruit. [Who can blame them?] You can attract bats to your garden for the evening shift by installing a bat house.
Deer are the bane of gardeners wherever they are found. These animals can leap small buildings in a single bound. Oh, wait, wrong story. But deer can wipe out an orchard, garden, or landscape, between feeding and trampling, in short order. Really high fencing (and I mean 7- or 8-feet high) might block deer. If your garden is on a slope, you will need fencing that is 10- or 11-feet high! Loud, scaring devices and various repellants can also be used to try and block these determined garden pests, but the effectiveness of these methods doesn’t last very long.
In California, we have deer mice, house mice, and meadow mice, also known as voles. Deer mice and house mice are mostly seed eaters that can wipe out a garden crop before it even starts. Voles are herbivores that will eat your bulbs, tubers, artichoke, beets, Brussels sprouts, celery, cauliflower, sweet potatoes, lettuces, tomatoes, turnips, cabbages… well, you get the idea. If that weren’t enough, voles will also chew the bark off your fruit and nut trees.
While poisons do kill mice, those poisoned mice can then be eaten by other wildlife, or your pets, so I urge you to avoid poisons. And those sticky boards, well, those are just cruel. Also, as the animal struggles to escape the glue, they tend to urinate and defecate and those materials then get slung around as the animal continues to struggle. Instead, good old fashioned mouse traps are still your best bet. They are usually an instant death and generally not very messy. Since all mice can carry hantaviruses, be sure to wear non-fabric gloves whenever handling mice, materials mice may have urinated on, or mice droppings. Also, be sure to thoroughly disinfect any areas inhabited by mice.
Moles and shrews
Shrews and moles may look like mice with deformed noses, but they are not rodents. They are more closely related to hedgehogs. There are 13 shrew species and 4 moles species in California, and they spend most of their lives underground, digging burrows and eating. For their size, shrews have voracious appetites, eating 1/2 to 2 times their body weight each day in worms, insects, and other invertebrates. They will also eat seeds, roots, and bulbs, but mice and pocket gophers are usually the culprits in those cases. Trapping is the most effective control measure, though chemical repellants and noisy, scaring devices can provide some protection.
Opossums may look prehistoric, but they can do your garden a good service. While they will sometimes eat fresh fruit and vegetables, opossums much prefer rotting produce, ticks, slugs and snails. In my book, that makes them a beneficial visitor. If an occasional tomato is lost, well, it seems a fair price.
Pocket gophers spend most of their time underground, digging burrows that lead to many of your garden and ornamental plants. We have 5 gopher species in California and they all feed on roots from below. They will also grab a tasty plant and pull it below ground to enjoy in relative safety. In a single night, one pocket gopher can destroy an entire garden row. Gopher traps are your best control measure.
Rabbits, hares, and pikas
Contrary to popular belief, rabbits are not rodents. They are lagomorphs. There, I said it. Now, what are pikas? And what’s the difference between rabbits and hares? Well, rabbits are smaller than hares, and hares, also known as jackrabbits, have longer legs and ears. Also, hares change color with the seasons, while rabbits do not. As for pikas, you probably won’t ever see them because they tend to live at elevations above the tree line, but they are cute. So are rabbits and hares - until they decimate your salad garden or other crops. Keeping rabbits and hares out of the garden is an unending battle. Since they can burrow, fencing alone is not enough. Raised beds with an exclusionary hardware cloth base may be your only real solution if these pests are feeding on your garden.
Raccoons are smart. And when they are not attacking your chickens or eating your pet’s dinner, they are probably busy eating your garden fruits, berries, nuts, corn, or other grain. Raccoons are attracted to compost piles, trash cans, and bird feeders. Raccoons may also try using your house, chimney, or garage as a nesting site. While young raccoons are adorable, these nests mean the presence of urine, feces, and disease-carrying parasites. Also, unlike opossums, raccoons tend to carry several diseases, such as roundworm, distemper, and rabies. Raccoons are best controlled with live traps. As a furbearer, raccoon pelts have value, so you can probably find someone who will be happy to discharge a trapped raccoon. Otherwise, you can discretely relocate your visitor somewhere more appropriate, and less destructive. Just be sure to check on your legal obligations before you get yourself in trouble.
Wherever you live, you probably have rats. The two most common types of rats are Norway, or sewer, rats and roof rats. These pests are filthy, destructive, and difficult to get rid of. Rats carry diseases, chew through electrical wires, and can damage your home, along with your garden. Roof rats prefer avocados, berries, citrus, and nuts, while Norway rats prefer meat and grain. Before you protect your garden against these pests, be sure that there are no points of entry to your home. Once your house is secure, then you can start trapping outdoors in earnest.
There are spotted skunks and striped skunks. In either case, it is a good idea to stay at least 10 feet away from the back end of a distressed skunk. [By the way, skunks have terrible eyesight. If you find yourself closer than you would like, be very, very still, or move away very, very slowly. A startled skunk is an unpleasant experience.] Both skunk species will eat pretty much anything: garbage, compost, pet food, worms, fruit, berries, mushrooms, beetles and other insects, lizards, frogs, snakes, and even the occasional bird egg. Since skunks are the most common carrier of rabies in California, along with distemper, canine hepatitis, leptospirosis, and several other diseases, getting them out of your garden (or out from under your porch) is a good idea. This is best done by professionals. Very often, your local Animal Control Office will remove skunks for free. Once a skunk family is removed, it is important to block whatever area, or remove whatever feature, attracted them in the first place. Otherwise, you will just get a new skunk. If you are unfortunate enough to be bit by a skunk, see your doctor right away. Seriously.
There are two major types of squirrels: tree squirrels and ground squirrels. If I didn’t have dogs, I would probably have nothing to show for all my work in the garden because of squirrels. I was surprised to learn that they will eat oranges, tomatoes, blueberries, pears, and more. Adding insult to injury, squirrels will, like birds, often only take a bite or two before moving on to the next delectable piece of fruit, leaving a trail of potential disease behind them everywhere they go. Hardware cloth and chicken wire are the only reliable barriers to squirrel feeding, though I have had some success with a repellant called Bobbex-R.
Finally, our pets.
We love our pets. There’s no denying that cats and dogs have a very special place in our hearts. That being said, we do not want cat feces next to our lettuces, or dogs digging up rows of beans or tomatoes. As much as your cat may love being outdoors, researchers at UC Davis have demonstrated that your cat is perfectly happy and actually safer kept indoors. Being stealthy predators, cats can decimate local bird, reptile, and amphibian populations, and we need those other creatures more than your cat needs time outside. Dogs can be trained to provide several beneficial services in the garden. My two dogs will chase squirrels, raccoons, rats, mice, opossum, jays, and cabbageworm butterflies out of my garden. Since most of my gardening is now done in raised beds, I don’t have to worry about the dogs running through them.
While we need to learn how to live and let live, there is nothing wrong with protecting what is yours. This is especially true for disease carrying pests. In some cases, it is simply easier to fence in your crops with netting and tree cages. For those mammals in the garden that must be killed, please use the fastest, most painless method.
How do you manage mammals in your garden?
Small, red delta pheromone traps (if you can find them) may also be used in April through June, depending on where you live. Check your trap every 2 weeks through November. The California Extension Office has an excellent male vine mealybug identification information sheet.
Mealybugs have been around for a long time. There is a relatively new, invasive mealybug that may be attacking your grapes.
Traditionally, California grape growers have had to watch for grape mealybugs, obscure mealybugs, and long-tailed mealybugs. These species generally do not cause significant problems, as long as their populations do not get out of hand. They are easy to recognize because of the clusters of gray, soft-bodied females gathering on the underside of leaves and in nooks and crannies. The invasive vine mealybug is another problem altogether.
Vine mealybugs (Planococcus ficus) are native to the Mediterranean areas of North and South Africa and Europe. Vine mealybugs were first seen in California in the mid-1990s and had spread to 17 California counties by 2011. Vine mealybugs are now considered a significant pest of grapes, figs, avocado, apple, bananas, mango, citrus, date palm, and several ornamental plants.
Vine mealybugs are difficult to see because they spend most of their lives protected under the bark, on roots, and around developing buds. Only during spring, when they become active again, can you sometimes see them moving away from the roots and trunk and into the leaf canopy. By summer, vine mealybugs may be found under the bark of first- and second-year canes, among fruit clusters, and under leaves. Sometimes, ants can be seen providing the mealybugs with transportation to their summer feeding grounds.
Vine mealybug description
Vine mealybug females are 1/8 of an inch long, pink, oval-shaped, and covered with a white, mealy wax that also covers filaments (spines) along the sides and posterior end. These filaments are shorter than those seen on other mealybugs, and there are no long tail filaments. Like their cousins, vine mealybugs have a segmented body. Males are tiny, winged, and you’ll probably never see them, unless you have a 30x microscope. They are 0.7 inches long, amber colored, with beaded antennae, one pair of wings, and 4 tail filaments that may stick together. It is important to know which mealybugs you are dealing with. If you see mealybugs, try to collect some and place them in a sealed plastic bag, or in a container of alcohol, and take them to your local County Extension Office for identification. This also helps authorities better understand the spread of this invasive pest.
Vine mealybug lifecycle
In summer, females lay 300 to 700 eggs in the leaves above the fruit in little pouches, called ovisacs. First instar nymphs, called crawlers, are orange and very tiny. During winter, only nymphs are present. They can be found hiding under the bark around the graft union, below the base of spurs, and around pruning wounds. There can be 3 to 7 generations a year.
How to control vine mealybugs
Being an invasive pest, vine mealybugs do not have as a many natural predators as their native cousins. Because vine mealybugs are such a serious threat to California grape growers, parasites of these particular mealybugs have been released in the state. This has helped somewhat, but eradication appears to be impossible at this point. Since these beneficial insects are unavailable to the home grower, the best things you can do to protect your vines is to inspect them regularly, especially during spring, monitor and control ant traffic with sticky barriers, and to quarantine new vines and other plants before installing them. Also, sanitize your tools regularly. Vine mealybugs also feed on burclover, malva, black nightshade, sowthistle and lambsquarters, so controlling these weeds can also help prevent infestation.
Damage caused by vine mealybugs
Vine mealybugs are phloem sap suckers that produce significantly more honeydew than native mealybugs. This honeydew attracts protective, disease-carrying ants and creates a growth medium for sooty mold on fruit clusters. These invasive pests can also carry grapevine leafroll viruses and corky bark disease. Vine mealybugs reproduce at a much faster rate than their native cousins.
Protecting your grapevine from vine mealybugs is an important step toward providing your family with fresh, delicious, organic, homegrown grapes.
You’ve proba-bly never heard of proba bugs. They are another relatively new pest on the garden scene. And they love artichokes.
Proba bugs (Proba californica) have been around for some time, but they used to prefer coyote brush. Coyote brush is a common native plant found along highways in agricultural areas of California. At some point (around 1997) a proba bug decided to give artichokes a try. From that moment on, proba bugs have become an increasing threat to artichoke plants. So, what do they look like?
Proba bug description
Adult proba bugs are plain brown and only 0.2 inches long. [That means you could line up 3-1/2 proba bugs across the top of a dime.] Nymphs start out looking like pale yellowish green aphids, except that they move a lot faster than aphids, due to their long legs. During the next to developmental stages (instars) they are reddish-brown, and then they develop light and dark bands on they abdominal area during the final two instars. [I couldn't find any usable photos of proba bug nymphs - sorry!]
Proba bug lifecycle
Proba bugs are active year round (just a lot slower in winter). As temperatures begin to rise, usually in March, they begin feeding and breeding in earnest. Eggs are laid on artichoke petioles (leaf stems) and hatch within 20 to 30 days. Nymphs go through five instars before reaching adulthood.
Damage caused by proba bugs
The damage caused by proba bugs is similar to that of lygus bugs, only proba bugs are more aggressive in their feeding habits. Adults and nymphs feed on young artichoke leaves and at the base of developing buds. They feed by piercing the tissue and injecting a toxin that kills plant cells. As the surrounding leaf tissue continues to grow, these punctured areas turn into brown dead spots that dry and fall off, leaving a shot hole appearance. Feeding on the base of flower buds causes the bud [the part we eat] to turn black. Not very appetizing. This phytotoxin also causes stunting and deformed flower buds. Severely affected leaves will be smaller than normal and chlorotic.
Controlling proba bugs
Until relatively recently, commercial artichoke fields were treated with organophosphates and chlorinated hydrocarbon insecticides. Use of these neurotoxins is being phased out, so proba bugs are becoming more of a problem. Infested fields can lose 20 to 30% of the harvest to proba bugs. Farmers are now removing the coyote brush near their fields and tilling the crop residue under, in a practice called stumping, to help combat this pest.
Natural predators, such as big-eyed bugs, damsel bugs, minute pirate bugs, and spiders all feed on the nymph stage of proba bugs, so avoid using broad spectrum pesticides.
You can help protect your artichoke plant by cutting the plant off at ground level, once flower production is done for the year, and monitoring for signs of infestation in March and April.
Predaceous ground beetles are a large family of beneficial insects that live in the soil.
You may see them scurrying across the ground, but mostly these members of Carabidae stay hidden in darkness. There are over 2,500 species of predaceous ground beetles in North America. They are mostly nocturnal and tend to hide under leaf litter and in the soil, though some species are attracted to lights at night.
Predaceous ground beetle description
Predaceous ground beetles are medium to large (1/3 to 2/3 inches long), shiny black or reddish beetles with long legs. Some species have brilliant coloration, and the shape can vary considerably. They have long, antenna with 11 segments and no knobs (clubs) at the end. The abdomen is large and rectangular, with a narrow thorax. While they can fly, they mostly prefer to run, which they do very quickly. Predaceous ground beetles look a lot like plant-eating darkling beetles. To tell them apart, you need to look closely enough to see if the second segment of the hind leg (trochanter), found between the coxa and femur, is enlarged. If it is, you have a predaceous ground beetle. Also, the antennae of predaceous ground beetles are attached just below a distinct ridge on the sides of the head.
Predaceous ground beetle life cycle
Eggs are laid in moist soil. When they hatch, larvae that look similar to earwigs emerge. These larvae feed voraciously on slugs and snails, and many bothersome soil dwelling insect larvae and pupa. These pest insects include masked chafers, caterpillars, grubs, tussock moth and gypsy moth larvae, other beetles, and maggots.
While predaceous ground beetles will occasionally eat seeds and organic litter, they prefer meat to vegetables. In fact, adult Calosoma sycophanta (affectionately known as caterpillar killers) eat several hundred caterpillars in their 2 to 4 year lifespan, and their larvae eat up to 50 caterpillars before transforming into adults! While not exactly predaceous, Lebia grandis loves to feed on potato beetle eggs and larvae.
So, the next time you see a black beetle running across the patio, look for fat legs and eyebrow ridges before squashing it!
Mexican fruit fly larvae travel the world in infested fruits.
Cousin to the dreaded MedFly, melon flies, and spotted wing drosophila, just to name a few, Mexican fruit flies (Anastrepha ludens), or MexFlies, are a major agricultural pest. Quarantines are part of the ongoing battle against fruit flies, so it’s a good idea to check your state’s quarantine listing, or your local Department of Agriculture, periodically to see if your area is included.
History of Mexican fruit flies in the U.S.
First found in the U.S., in Texas, in 1903, Mexican fruit flies were seen again in 1927. By 1954, they had spread to Florida, Arizona, and California. It is estimated that these pests have cost farmers $1.44 billion in damages. Mexican fruit flies are subject to eradication programs that include capturing, sterilizing, and releasing males that interrupt the breeding cycle.
Mexican fruit flies have been expanding their range for several years now, and it’s not simply by catching a ride on an infested piece of fruit. Commercial agriculture brings crops to non-native regions, introducing them to local pests and diseases. For example, the mango, from India, only became a popular food of Mexican fruit flies after it started being grown in Central American and Mexico.
Mexican fruit flies prefer grapefruit, oranges, tangerines, mango, apple, peaches, nectarines, avocado, and pear. More recently, they have been found on figs, bananas, prickly pear cactus, cashews, papaya, guava, pomegranate, peppers, tomatoes, squash, beans, quince, Japanese persimmon, passionfruit, pummelo, and arabica coffee. [Coffee?!!?} Not only is the Mexican fruit fly range expanding, but so is their diet.
Mexican fruit fly description
Slightly larger than a housefly, Mexican fruit flies are 1/3 to 1/2 of an inch long. They have a yellow or brown body and distinctive wing patterns. Also, adult females have extra long ovipositor sheathes (egg-laying tubes). The wing patterns include a costal spot (C), an inverted-V, and a sideways S shape. Larvae are slender white grubs with mouth hooks, and a slightly flattened back end.
Mexican fruit fly lifecycle
As far as fruit flies go, this particular species is relatively long-lived. Individuals can survive for 11 to 16 months. Females lay over 1500 eggs in their lifetime. Eggs are laid in groups of 10, on the skin of a fruit, preferably one that is slightly damaged. This provides an easy point of entry for Mexican fruit fly larvae, along with many other pests and diseases. In a week or so, after being deposited, the eggs hatch out larvae that burrow into the fruit and start feeding. As they feed, the larvae take on the color of the fruit their are eating, so you may not notice right way, after taking a bite of an infected fruit.
Larval feeding continues for 3 or 4 weeks, depending on temperatures. Then, larvae drop to the ground, where they pupate in the soil. During this seeming pause in development, the slug-like larva is converted into a winged adult that begins breeding immediately after emerging, starting the whole process over.
Controlling Mexican fruit flies
Because they spend most of their lives inside fruit, insecticides are not effective against Mexican fruit flies in the larval, egg, or pupal stages. There is a tiny, repeated window of opportunity for treatment of adults, but only if direct contact is made with the insecticide. Generally, adults will simply fly away from treated trees and return a few days later, after it has worn off. Commercial growers use complex bait and trap methods that are unavailable to small scale growers.
So, the only thing you can do if you suspect that Mexican fruit flies have found their way to your garden is to immediately contact your state's Pest Hotline, or your local Department of Agriculture. It is best to leave controlling these pests to the pros.
Melon flies could end up costing California farmers over $4.5 billion if they ever get a toe-hold in the state.
Melon flies (Bactrocera cucurbitae) are a type of fruit fly. Native to India and Asia, melon flies were first seen in Hawaii in the late 1800’s. They have now become a devastating pest on the Islands. Quarantine stations have worked long and hard to prevent this pest from entering the Continental U.S. The melon fly was first seen in California in 1956, and several other times since, but whenever melon flies are identified stateside, eradication programs immediately go into affect. These programs use pheromones to attract male melon flies. These males are then sterilized and released. This messes up melon fly breeding. So far, this method has been effective. So, why would a gardener care, if the pest isn’t even here? Because maybe it is.
Melon fly host plants
It would probably be easier to list the plants that are not seen as food by melon flies, but it is important to know where to look, and to know what to watch for, so here’s the fruit fly menu of favorites from your garden:
Melon fly description
The size of a house fly, melon flies are mostly orange or yellow and brown with a pale black T-shape on the abdomen and distinct wing patterns. Wings are clear with a large brown spot at the tip and a brown stripe along the back edge and along the base. Melon fly antennae also have an especially long third segment. Melon fly larvae (maggots) are creamy white, without legs, somewhat flattened at the back end. Maggots are less than 1/2 an inch long. Pupae are somewhat smaller than the maggots, held in a protective case that can be dull white or red, or brownish yellow. Eggs are very tiny, white, and somewhat elliptical.
Melon fly lifecycle
A single female melon fly can lay 1,000 eggs. Eggs are laid on young fruit and tender new stems, which will provide food for newly hatched maggots. Eggs that have been laid under the skin of fruits, or in host plant stems, flowers, and exposed roots, will hatch and the feeding damage begins. There are three larval stages, or instars. After feeding continuously, mature maggots drop to the ground, where they burrow into the top inch of soil and enter a pupal stage. There can be 8 to 10 generations a year.
Melon fly damage
During the heat of the day, adult melon flies rest on the shady undersides of leaves. When temperatures are more comfortable, they feed on nectar, decaying fruit, sap, and bird poop. [Keep in mind, as these pests fly from one food source to another, they can be carrying pathogens from the bird poop to your fruit crop.] Tunneling and feeding create points of entry that allow bacterial, fungal, and viral diseases to enter. Generally, the fruit ends up rotten and inedible.
Melon fly control
Unfortunately, there are not any effective controls available to the home gardener. You can certainly rake up the soil under and around potential host plants, to spot, remove, and report any pupal cases you find, and be sure to quarantine new plants. Currently available insecticides have not been found to work against melon flies.
If you think you see a melon fly, please make every effort to capture or kill it. Then call the CA Pest Hotline at 1-800-491-1899, or your local Department of Agriculture, to report it. Only by working together can we protect commercial agriculture and our own gardens from the melon fruit fly. And don’t smuggle fresh fruit or produce across state lines. There’s a lot more at stake than you might think.
Vedalia beetles are a breed of Australian ladybug that devours their weight in cottony cushion scale pests found on citrus, olives, roses, magnolia, and acacia. The vedalia beetle claim to fame is that it was California’s first attempt at biological pest control
Back in the late 1800s, cottony cushion scale was decimating California’s citrus trees. In 1888, vedalia beetles (Rodolia cardinalis) were imported from Australia to counteract that pest, and it saved the California citrus industry
Vedalia beetle description
Like other lady beetles, vedalia beetles are easy to recognize because of their domed body shape and stubby antennae. The difference being coloration. While bright red lady bugs feature dark spots, vedalia beetles feature a much darker red dome with splotchy black markings. Adults are approximately 1/16 to 1/8 of an inch long and covered with fine hairs that can make them look more grayish than red and black. Larvae are elongate, grayish, and can look like tiny alligators.
Vedalia beetle diet
While the bright red variety most of us think of as ladybugs feeds heavily on aphids, vedalia beetles prefer cottony cushion scale insects. Adult vedalia beetles simply chew up their prey, while younger larvae pierce their victims and suck out their juices.
Vedalia beetles start out as tiny red eggs. These eggs hatch out into tiny red larva. Vedalia larva start feeding right away and they go through several instars, or developmental stages, as they grow. They continue to feed until just before pupating. Then they attach themselves to a leaf as they prepare for their final transformation. [Unlike other insects that pupate, if you touch a healthy vedalia pupa, it should move.] One week later, an adult vedalia beetle emerges, ready to lay 100 to 200 eggs in its 1 to 3 month lifespan.
Combined with a parasitic wasp (Cryptochaetum iceryae), cottony cushion scale is now well under control in California, without the use of any chemicals. Since vedalia beetles are extremely sensitive to pesticides, it is a good idea to inspect an area for these beneficial insects before spraying chemicals.
With a name like insidious flower bugs, I had to write about them.
These predatory insects are a type of minute pirate bug. They eat many small garden pests and their eggs. And they bite.
Insidious flower bug bites
Yes, insidious flower bugs (Orius insidiosus) bite. We don’t know why. And it hurts. A lot. Some people react to these bites with welts, swelling, or redness, while others have no reaction [other than the pain]. Since these insects are not quick to fly away after biting, you may get some satisfaction out of ending them, but that wouldn’t be in your garden’s best interest. And insidious flower bug bites cannot actually harm you. In fact, they are so tiny that robber flies eat them. [Thanks to Jim Elve for permission to use this amazing photograph!]
Despite their bite, insidious flower bugs really are beneficial. They feed heavily on thrips [their favorite food], corn earworm eggs, mites, spider mites, small caterpillars, bollworms, whiteflies, scale insects, European corn borers, armyworms, potato leafhoppers, and a slew of aphid varieties, including spotted tobacco aphids, corn leaf aphids, and potato aphids. Insidious flower bugs are so beneficial, that they are raised commercially as a biological control against thrips, European red mites, twospotted spider mites, and most aphid varieties in eggplant, strawberry, cucumber, and sweet peppers crops. Research conducted in Florida found that insidious flower bugs were more effective at controlling thrips on sweet peppers than insecticides. Other research has demonstrated similar results with twospotted spider mites on bean plants, and soybean aphids on soybeans.
Insidious flower bug description
These mixed blessings are small, only 1/5 of an inch long. They tend to be flattened, with an oval to triangular shape. They are black with white markings. Nymphs are yellowish-orange to brown, wingless, and teardrop shaped. If you look at an insidious flower bug under a microscope, you can see that they have piercing mouthparts, called beaks, which they use to repeatedly stab and suck the juices from their prey.
Orius insidiosus lifecycle
Insidious flower bugs seem to come out of the woodwork in late summer, though they have been around since they hatched, starting in spring. Eggs are laid in plant tissue, then hatch into nymphs, going through five instars before reaching adulthood. This takes approximately 20 days, and there can be several generations a year. Most of their diet consists of insects and insects eggs, but they occasionally eat plants and pollen when prey is scarce.
Attracting insidious flower bugs
Despite the bite potential, these predators are good to have around. You can attract them to your garden by growing alfalfa, buckwheat, soybeans, cotton, grapes, and most deciduous fruits.
You can reduce the chances of getting bit by wearing dark clothing on hot days in late summer. For the most part, insect repellants do not work against these garden visitors.
Antlions are fierce predators of the garden.
Cousin to lacewings and owlflies, and often mistaken for dragonflies or damselflies, these beneficial insects fly at dusk and at night. It is their larvae, however, that do the most damage to garden pests, such as ants and termites.
Adult antlions live for only 20 to 25 days, and most antlion species do not eat anything. Those that do only eat pollen and nectar. Instead of dining, they flutter around at dusk and during the night, attracted to lights and flames, in search of a mate. After mating, the female lays her eggs in sand or plant debris. Those eggs hatch into ferocious larvae that feed until they are ready to pupate into adults. This entire cycle make take 2 to 3 years to complete.
Adult antlions have two pairs of clear, thin wings, and a narrow abdomen. They can be differentiated from damselflies by their long, clubbed antennae. Also, adult antlions don’t appear to fly very well.
Antlion larvae are often called doodlebugs because of the squiggly trails they leave behind. Antlion larvae are spindle-shaped, with a plump middle and three pairs of legs. [You may have seen a variation of an antlion in the ‘Ceti eels’ from Star Trek II: Wrath of Khan]. Antlions appear to have a mobile neck (prothorax) and the head is flattened with very large, heavily ‘toothed’ jaws. Those teeth are actually sharp, hollow tubes. Within these jaws of death, antlion larvae have a canal that carries venom to immobilize their prey and enzymes to liquify them, once they are paralyzed. If that weren’t terrifying enough, antlion larvae feature forward facing bristles that help them to stand stand ground against significantly larger prey. One weird thing about antlion larvae is that they do not have an anus. Instead of releasing waste, they store it for later use as a building material for their cocoon. Any unused waste material is then released at the end of its pupal stage. [I suppose that it’s no surprise that antlion cocoons look like rabbit droppings or bird poop…]
Signs of antlion habitation
How would you know if antlions are in your garden? You might see adult antlions fluttering around your porch light. Or, you might see holes in the ground. While some antlions hide in wait for their prey under leaf litter, other species of antlion larvae trap their prey in pits. They build these traps by walking backwards in circles, flipping grains of dirt and sand out of the hole with its very large jaws. Ultimately, they end up with a very steep-sided hole that can be 3/4” to 1-1/2” deep. The soil or sand around the pit is loose. At the bottom of that pit, the antlion larvae waits quietly for its next meal. As an unsuspecting insect walks by, they may fall in. When they do, it’s all over for them! As soon as prey fall in, the antlion quickly flips more soil out of the hole, making it deeper and causing grains of soil to fall on the prey, knocking it deeper into the hole. Finally, the insect is grabbed by the antlion’s large jaws and the liquefaction of its insides begins. After everything has been sucked out, the husk it thrown out of the hole and everything is tidied up for the antlion's next guest.
There is a tale that says you can talk antlion larvae out of their holes. Simply bend down, close to the hole, and tell the antlion to tell you what you want to know. At the sound of your voice, the antlion emerges from their hole, but why? The tale says that the larvae want to hear what you have to say. What’s really happening, is the soil is disturbed by your movement and the sound vibrations of your voice, so the antlion thinks it either has lunch, or a housekeeping job to attend to.
There are over 600 antlion species worldwide. Antlion larvae are often used as fishing bait, and some people keep them as curiosity pets. How many do you have in your garden?
While these furry, clumsy, easy-going pollinators can sting you, repeatedly even, they generally choose to ignore us. [Unless they get caught in a certain young girl’s unruly long hair. Believe me. I speak from personal experience.]
The name bumblebee, or bumble bee, comes from the characteristic buzz (bumble) of this gentle pollinator. Before it was called bumblebee, it was known as a ‘humblebee’ and before that a version of a ‘clumsily flying buzzing beetle’ or ‘dumbledor’ was used. [I’ll bet you weren’t expecting that one!]
Charles Darwin had this to say about bumblebees in his book, On the Origin of Species (1859):
I have [...] reason to believe that humble-bees are indispensable to the fertilisation of the heartsease (Viola tricolor), for other bees do not visit this flower. From experiments which I have tried, I have found that the visits of bees, if not indispensable, are at least highly beneficial to the fertilisation of our clovers; but humble-bees alone visit the common red clover (Trifolium pratense), as other bees cannot reach the nectar.
Bumblebees really are clumsy fliers. They bump into stems, leaves, and branches quite frequently. Research conducted at the California Academy of Sciences and UC Davis explored how bumblebees are able to withstand the frequent collisions they experience each day. When I say frequent, I mean once a second, on average.
Cousin to honeybees (Apini), orchid bees (Euglossini), and stingless bees (Meliponini), bumblebees (Bombini Bombus) have pollen baskets on their legs, making them all corbiculate. Fossil evidence of the common ancestor to these beneficial insects dates back 100 million years. Bumblebees have been around for 25 to 40 million years, depending on who you ask.
Bumblebees are more commonly found in higher latitudes and higher elevations than other bees. There are even two species found in the Arctic! This may be due to their fur coats, but scientists explain that bumblebees are able to regulate body temperature, using the sun’s radiation and ‘shivering’ to generate heat. Unlike other bees, bumblebee queens are known to incubate their eggs.
Like other insects, bumblebees have a three part body made up of the head, thorax, and abdomen. The head features two compound eyes and three primitive eyes, mouthparts, and antennae. Female bumblebee antennae have 12 joints, while males have 13. The thorax is where the wings, legs, and wing muscles are found. The abdomen contains the digestive and reproductive organs and the stinger.
Bumblebees have two pairs of wings, a fore wing and a rear wing. The wings connect to muscles that are attached to the inside of the plates that make up a bumblebee’s exoskeleton. A waxy substance is secreted from glands and discharged from between the plates. It looks a lot like dandruff. Bees groom the wax into clumps and use it to build honey pots, egg coverings, and as nesting material. Bumblebees do not have ears. We do not know if they can sense sound waves through the air. They do seem to be able to sense vibration through other materials, such as the ground.
Unlike the oblong honey bee, or the shiny black female carpenter bee, your average bumblebee looks round and furry. This is because they are covered with very soft, finely branched bristles, called setae. Bumblebees can usually be differentiated from golden male carpenter bees by the presence of contrasting bands and other markings. This aposematic coloration serves as a warning to would-be predators. Some other insects, such as hoverflies, mimic and are protected by this coloration. This is called Batesian mimicry. Bumblebees come in a variety of sizes, ranging from 1/2 an inch, up to one-and-a-half inches long. [Don’t worry, that big one lives in Chile and is affectionately referred to as a ‘flying mouse’ - okay, maybe not affectionately.]
Bumblebees store fat in their body. This fat is used up during hibernation. Bumblebees do not use the bee dances common to honey bees, but they do exhibit social learning. Youngster bumblebees are frequently bumped off of favored flowers by more mature bees. In a lab experiment, bumblebees were taught to move an object in exchange for a reward. Untrained bees who observed the task-reward process learned it more quickly than those bees who observed the same exchange performed by an inanimate object. In fact, observer bees consistently improve on the methods used initially, implying at least some level of cognition.
Most bumblebee species are social insects. They live in relatively small colonies, led by a queen. Honey bee colonies hold 10 to 60 thousand workers, during peak honey production, while a bumblebee colony may only contain 50 to 1,500 individuals.
Bumblebee nests are first constructed by an over-wintered queen. After collecting pollen and nectar from flowers and finding a suitable nesting site, the young queen will build wax pots to store food, and wax cells to receive her eggs. As the eggs hatch into larvae, the cells are expanded into a lumpy mass of brood cells. Nesting sites can be in or on the ground, or in tussock grasses, depending on the species. Bumblebee nests are a food source for badgers and other insectivores. Bumblebees normally range only a mile or so from the nest.
A queen bumblebee performs a mating flight before retiring to her nest. There, she will ‘decide’ whether or not to use the collected sperm to fertilize each egg she lays. Unfertilized eggs develop into males. Fertilized eggs grow up to be hormonally suppressed worker females or fertile queens. Mature males are forced out of the nest by the females. Males and new queens live independently from the colony, sleeping in flowers or holes in the ground.
Bumblebees feed on nectar, and pollen is collected for the young. Bumblebees lap up nectar with a long, hairy tongue, called a proboscis. The tip of the tongue may also be used as a straw. Because the tongue is so long, bumblebees are able to gather nectar from (and pollinate) deeper flowers than honey bees, which have shorter tongues. When bumblebees fly, the proboscis is often folded under the head. Some bumblebees feed on flowers from above, the way other bees and hummingbirds do, while other ‘rob’ the nectar by cutting a hole in the base of the flower. It is called ‘robbing’ because this behavior avoids pollen transfer. [The metabolic rate of bumblebees is 75% higher than a hummingbird’s.]
Some species of bumblebee leave a scent marker behind on a flower, after it has fed. This marker deters other bumblebees from feeding on that flower, until the marker fades. Once a bumblebee has eaten its fill and collected all of the nectar it can carry, it returns to the nest and deposits its riches in brood cells, for the young, or in wax cells, for storage. Unlike honey bees, which process nectar into honey, bumblebees store it as-is.
Bumblebees as pollinators
Bumblebees are powerful pollinators. As they feed, moving from flower to flower, they collect and deposit pollen. Bumblebees are commonly used in greenhouse tomato production. They are fed sugar water so that they do not need to harvest nectar, and can focus exclusively on pollen.
[Did you know that pollen is left behind at each flower because the act of flying causes the bee to build up a static charge? The plants, being rooted in the ground, are, well, grounded. The electrically charged pollen grains on the bee are attracted to the stigma, which happens to be the best grounded part of a flower, while the flower’s grounded pollen is attracted to the bee’s statically charged body. How bizarre and amazing is that?!!?]
Bumblebees also pollinate plants by a method called buzz pollination, or sonication. They do this by disconnecting their wings from their flight muscles and vibrating their flight muscles at a frequency very close to middle C. [The frequency varies depending on plant species.] The force generated during sonication can reach 30 Gs, which is almost more than a human can tolerate! This vibration causes a flower’s pollen to burst forth. This method is particularly effective on blueberries and members of the nightshade family, such as tomatoes, tomatillos, and eggplant. Sweat bees, carpenter bees, and stingless bees sonicate, but honey bees do not. PBS has an amazing video of buzz pollination.
There are over 250 species of bumblebee worldwide and several of them are in trouble. This is especially unfortunate when you realize that native bumblebees are responsible for a lot of pollinating. Some of the more common bumblebees include:
These bumblebee species have not been seen in recent years:
Cuckoo bumblebees, or brood parasitic bees, do not live in colonies. Instead, cuckoo queens will invade a nearby bumblebee nest, kill the queen, and then start laying their own eggs, which end up being cared for by the murdered queen’s workers. [You can tell the difference between a cuckoo bumblebee and a social bumblebee by looking closely at the back leg: nesting female bumblebees have a pollen basket, which is bare and shiny, whereas a cuckoo bee hind leg is covered with hairs. They transport pollen by wedging it between the hairs.]
Like the European honey bee, bumblebee numbers are declining. This is largely due to habitat loss, pesticide use, and the mechanization of agriculture. You can counteract some of these effects by planting flowers that attract and provide for bumblebees.
Bumblebees are attracted to flowers by both sight and smell. They seem to prefer flowers that grow on spikes, such as salvia and lavender. This may also be because these flowers tend to be blue, purple, or white, favorite colors of bumblebees. Bumblebees are also attracted to members of the sunflower family. The most important consideration when planting to attract bumblebees is that the stems are sturdy enough to support these heavy pollinators. Bumblebees can also see a flower’s temperature, as well as its electrical field.
You may very well already have plants that attract bumblebees. If you allow your kale and other cabbage family members to bolt in early spring, bumblebees will take advantage of the blooms, and you will add these plants to your foodscape as seeds are dispersed later in the season. Other popular flowers that attract bumblebees include anise hyssop (Agastache foesniculum), guaras (Guara lindheimeri and other cultivars), bog sage (Salvia uliginosa), Mexican sage (S. mexicana) and many members of the mint family, including basil, thyme, sage, and rosemary. Native plants, such as manzanita, ceanothus, CA buckwheats, penstemons, currants, and gooseberries will also attract and provide for these hard working beneficial insects.
Bumblebees are housing opportunists. They build nests in upturned planter pots, abandoned mouse burrows, and under boards. If you have a square foot of bare, undisturbed soil and the right flowers, you are pretty much guaranteed a visit.
The U.S. Forest Service offers a nice poster of western bumblebees with dietary notes. You can also learn more about bumblebee conservation from the Xerces Society.
Most of us are familiar with the red-domed, black-spotted variety of ladybug, but there are black lady beetles, too!
aAlso known as black ladybirds and Forestier’s ladybird, Rhyzobius forestieri is a true garden hero when it comes to fighting scale insects.
Black lady beetle description
Black lady beetles are smaller than our common red ladybug. You could fit 5 or 6 of them across the top of a dime. If you look closely, you will see that their dark brown or black bodies are covered with tiny, short hairs. They have dark legs and tan antennae. If you were to flip one over, you would see that the underside is also tan. Adult and larval forms of black lady beetle have 3 pairs of legs and adults can fly.
Black lady beetle have the same alligator-like shape as common ladybug larvae but they are more gray. Pupal cases look a lot like tiny snail shells.
Black lady beetle lifecycle
Nearly microscopic eggs are laid next to, under, or up against scale insects. When the eggs hatch, they begin feeding on scale insects as they go through four developmental stages, or instars. Ultimately, they enter a pupal stage. When adults emerge from the pupal case, they mate and the whole cycle begins again.
The next time you see a tiny black beetle, make sure it’s not one of the Good Guys before squishing it!
The Mediterranean fruit fly has reappeared in California!
Periodically, in the world of gardening and agriculture, a cry goes out across the fields, farms, and front porches of the world, announcing that a medfly has been found. In this case, a medfly was found in Half Moon Bay.
You might think that a tiny fruit fly is No Big Deal, but this short, squat, orangish flying insect has the dubious title of World’s Worst Agricultural Pest.
The California Dept. of Food & Agriculture estimates that a permanent infestation of the Mediterranean fruit fly, or Medfly, would cost California businesses nearly $2 billion a year!
Native to sub-Saharan Africa, medflies (Ceratitis capitata) have slowly been making their way around the globe, usually riding on fruit and other infested crops. Medflies are about 1/4” long. They have a black thorax, marked with silver, and a tan abdomen with dark stripes. The wings are clear, with two light brown bands and gray flecks at the base. Their eggs look like those of other fruit flies: they look like tiny white bananas. Larvae are white, legless, and pointed at the back end. Pupae are encased in a hard, shiny brown puparium.
Damage caused by medflies
Medflies lay their eggs in the skins of over 250 different fruit, nut, and vegetable crops. When the eggs hatch three days later, the maggots burrow into what we normally eat, making it inedible. Once maggots have eaten their fill, either the rotting fruit falls, or they drop to the ground where they pupate in the soil. In one week, an adult emerges and the whole cycle begins again.
Crops affected by the medfly
It would probably be easier to list the crops not affected by medflies, but this should give you an idea: apples, apricots, avocados, cherries, figs, grapes, grapefruit, lemons, limes, melons, nectarines, oranges, peaches, pears, persimmons, plums, pomegranates, sweet peppers, tangerines, tomatoes, and walnut.
The ripple effect
Like most things in life, this situation is not limited to bug-infested food plants. Commercial and home growers will end up using more pesticides to counteract this insect, which can lead to more ground water contamination and chemical resistant pests. Also, areas with medfly populations are unable to sell their produce, infested or not, to other states and other countries. Finally, native plants that produce fruit or nuts can also be attacked by this pest.
The first appearance of a medfly in California took place in 1975. I remember hearing about it in the news - everyone was talking about it. The government declared a “state of emergency” and 100 square miles were placed under quarantine, and 600 million sterile male medflies were released to interrupt breeding. Malathion was sprayed all over the place. It cost $1 million and took a year, but the medfly was eradicated. For a time.
When the medfly returned in 1981, Governor Brown delayed aerial spraying of malathion, claiming environmental concerns. That was when we learned that medflies reproduce and feed at astounding rates. In that case, the medflies needed only one month to destroy millions of dollars of crops, and to threaten billions more, over an area of 530 square miles. When it was realized just how devastating this pest could be, the California National Guard was called upon to create highway checkpoints to confiscate infested produce.
Now, when a single medfly is spotted, it is checked for gender and fertility, and then all the stops are pulled: aerial spraying, ground spraying, trapping, irradiation, releasing sterile male medflies, public information, and quarantines. Since 1985, medflies have been found in California in 2007 (Dixon), 2008 (El Cajon), and in 2017.
What can you do?
First, never, ever, EVER smuggle fresh produce, plants, or soil from infested areas into uninfested areas. Do not mail fresh produce into uninfested areas either. For more information, contact the California Dept. of Food and Agriculture at (650) 363-4700.
IF YOU THINK YOU SEE EVEN ONE MEDFLY, PLEASE REPORT IT!
Robber flies assassinate their prey in the air, injecting them with paralyzing neurotoxins and enzymes that liquify their preys’ insides. Also known as assassin flies, robber flies (Asilidae) aggressively hunt other insects. They often look more like bees or dragonflies to the casual observer. And they are in your garden, for better or worse.
Robber fly description
There are over 7,500 different species of robber fly, ranging in size from 0.2 inches up to 2 inches long. All of them are sturdy, bristled flies with a distinct mustache, made of of bristles (setae), called a mystax. Robber flies, like many other insects, have three simple eyes (ocelli), in a depression on top of their head, between two very large compound eyes. [Simple eyes, like ours, have only one lens, while compound eyes have many lenses.] Robber flies generally have robust legs with spines, and short, segmented antennae. Most species of robber fly have long, skinny bodies with stinger-like ovipositors, while others look more like bumblebees. Robber flies will inflict a painful bite with their proboscis (tubular mouth part), if they feel threatened.
Robber fly life cycle
There is surprisingly little known about the private lives of robber flies. They seem to prefer dry, sunny, open environments. Each robber fly can live for up to 3 years. Eggs can be translucent (hyaline) or pigmented, spherical or oval, depending on the species. Yellowish or white larvae, with tapered bodies and a dark head, are believed to live in leaf mold, rotting wood, and in the soil. There are four larval stages, or instars. Scientists are only now learning about the feeding behavior of robber fly larvae. It’s pretty strange. For one thing, the first instar does not eat insects; it probably eats dead things. The second instar eats beetle larva secretions. [Don't ask.] Later instars are actual predators. Robber fly pupa are naked and have leg stubs, so they can move around, similar to hornworm larvae.
Robber fly prey
Robber flies are generalists. That means they will chase after and kill pretty much anything that flies by, beneficial or not. That is why I said, for better or worse.” Robber flies will kill many garden pests, but they will also kill beneficial insects. Some of these prey insects are pretty substantial in size, compared to a robber fly. But, adult robber flies are excellent fliers. You can usually hear them coming, but for their prey, it’s already too late. Hiding in ambush, a robber fly spots its target, gives chase, and grabs ahold with its tarsi (front legs) before injecting a chemical cocktail that paralyzes the prey and liquifies its insides. The most common victims of robber fly attack include:
They have also been recorded feeding on:
And, hummingbirds. It’s rare, but it has happened. You can see some excellent video of robber fly behavior at Mike Blair Outdoors.
Have you seen any robber flies in your garden? Do you consider them to be Good Guys or Bad Guys?
Hoverflies, or syrphid flies, are one of the most beneficial insects you can attract to your garden.
Hoverflies are members of the Syrphidae family. There are over 6,000 species worldwide and 300 on the West Coast. Many of them mimic bees and wasps to discourage predators, but they are harmless to humans. Hoverflies mimic bees and wasps in other ways, too, as both predators and pollinators.
With so much variety, there is no one description that covers all hoverflies (also spelled hover flies). They can be as large as 3/4” long or so small that you won’t notice them. They can be black or colorful, spotted, striped, or plain. What they all have in common is the fact that they tend to hover over their favorite flowers. There are some bee flies that also hover, but they are equally beneficial as both pollinators and predators, so you don’t really need to know the difference* between the two species.
* If you really need to know the difference, hoverflies have shorter legs, a prominent beak, and a line along the back of their wings, while bee flies have longer legs, a sloping face, and clear wings. Also, bee flies are more likely to be hairy. There. Now you know.
Hoverfly larvae are blind and deaf. They are only 1/32 to 1/2 of an inch in length. They may be green, brown, yellow, or nearly transparent. They may have a white longitudinal stripe.
Not all hoverflies behave in the same way, but there is enough variety to safely assume these are bugs you want in your landscape and garden. Some hoverfly larvae are saprotrophs, which means they each decaying plant and animal matter in the soil. This improves soil structure and makes nutrients available to plants. Other hoverfly maggots are powerful predators, devouring a lion’s share of aphids and other plant-sucking pests.
Hoverflies as predators
Most hoverfly species larvae will eat aphids, thrips, mealybugs, mites, scale insects, and leafhoppers. That’s a good thing, because these pests spread several diseases, including curly top, powdery mildew, black spot, rust, and sooty mold, just to name a few! Other hoverfly larvae prey on caterpillars, slugs, and codling moth larvae. In my book, there are no bad hoverflies.
Hoverflies as pollinators
As adult hoverflies feed on nectar and pollen, they also pollinate many of your garden crops. In fact, hoverflies are second only to bees when it comes to pollination. Unlike bees, which tend to prefer specific species, hoverflies are generalists, landing wherever the picking looks good.
There are several insectary plants that attract hoverflies. Most of these plants provide pollen and nectar to the adult forms. Hoverflies prefer plants that have shallow or umbrella-shaped flowers. These plants are often members of the Umbelliferae or Apiceae family. Adding the following plants to your landscape is sure to attract these beneficial insects:
Research has shown that hoverflies prefer yellow and white flowers over other colors. Since organic pesticides, such as spinosad, also kill beneficial hoverflies, you may want to think twice about when you spray. Once flowers are in bloom, you may want to hold off.
Orchid trivia - One type of orchid, Epipactis veratrifolia, emits chemicals that mimic the alarm pheromones used by aphids. This attracts hoverflies, resulting in pollination. Stuff like that makes me wonder what else is going on that we never notice.
Birds in the garden: boon or bane?
The answer: both.
The presence of birds in a landscape indicates a healthy biodiversity. They eat many garden pests and may even help with pollination. That being said, birds can be a Royal Pain. They destroy seedlings, devastate crops, and can carry disease. Bird management can reduce the problems while increasing the benefits.
Benefits of birds
The image of a red-breasted robin tugging an earthworm from the soil is an icon of spring. Birds also eat crane flies, stinkbugs, armyworms, moths and their caterpillars, millipedes, spiders, slugs and snails, crickets and grasshoppers, inchworms, katydids, grubs, cabbage loopers, cabbageworms, and countless other garden pests. You may be surprised to learn that hummingbirds often eat spiders, gnats. flies, and ants, especially when they are raising young. Some birds eat the mosquitoes responsible for Zika virus, along with several other diseases. Birds facilitate decomposition by eating foods and then leaving nutrient-rich droppings behind. As birds eat the seeds of fruits and other garden crops, they help spread seeds for future crops.
Birds as pests
As birds devour garden pests, they will also eat beneficial earthworms, centipedes, bees, and butterflies. But crop damage is the real problem. Birds love seeds, fruit, and nuts. They will dig up seeds, devour seedlings, peck holes in fruit, and decimate nut crops. They are particularly fond of pea, bean, melon, and squash seeds. Birds can be major pests if you are growing hazelnuts, almonds, figs, pears, peppers, peaches and nectarines, apples, blueberries, blackberries, raspberries, grapes, saffron crocus or other bulbs, sorghum, or tomatoes. They can wipe out amaranth and quinoa crops. Birds can also carry diseases, such as San Jose scale. Scrub jays will steal eggs from your chickens and kill young chicks. Birds can also be troublesome when it comes to soil solarization. As they search for grubs and worms, they may lift the fabric, halting and reversing the solarization process. Finally, woodpeckers and sapsuckers can effectively girdle a tree as they feed if the holes are too numerous and go all the way around a tree trunk.
Birds and mixed crops
Some crops, such as sunflowers and currants, can be used to support biodiversity in the garden while still providing a harvest for your family. Fruit from currant bushes, and the seeds and leaves of sunflowers, are popular foods for many indigenous birds, especially goldfinches. You can protect your crops by placing paper bags over flower heads and fruit clusters, or you can simply grow more than you need and provide food for our feathered friends.
Local bird dilemma
Many European birds, such as sparrows and starlings, have made life difficult to nearly impossible for many of our indigenous birds. They take over habitat and food supplies, and are less fearful of humans, so our native birds are suffering. Bluebirds, goldfinches, and several wrens are being pushed into marginal habitats by these interlopers. In addition to habitat loss, they are also facing chemical toxins, cars, windows, plastic garbage, and improperly used netting. Their young are also vulnerable to squirrels, outdoor cats, and other predators. You can help these birds by installing native plants, providing a water source, and constructing bird houses with very small (1” diameter) openings. Anything larger and sparrows will pitch the eggs, kill the young, and take over. Birdhouses need to be placed on poles to be appealing to our native birds. Birdhouses hung from buildings and fences will not be used because they are vulnerable to predation.
To reduce the damage caused by birds in the garden, tree cages can be erected around fruit and nut trees. These structures a much easier to build than they sound, and cost very little. You can also protect newly planted seeds and seedlings with row covers.
Birds are a mixed bag, but it wouldn’t be a healthy landscape without them.
Cabbage looper larvae are common summer garden pests.
Nocturnal brown moths (Trichoplusia ni) fly in at night and lay tiny hemispherical eggs, singly or in clusters, on upper and lower leaf surfaces. Adult moths live 10 to 12 days. Females can lay 300 to 600 eggs in that time. Two to ten days alter, pale white larvae emerge and begin feeding on the underside of leaves of cabbage, broccoli, and other members of the brassica family. As the loopers grow, they move to the upper side of leaves and feed heavily, leaving large ragged holes. They also feed on tomatoes, kale, radish, lima beans, lettuce, peas, peppers, beans, spinach, squash, sweet potatoes, watermelon, cucumbers, potatoes, thyme, and collard greens, leaving behind clumps of dark green droppings.
Cabbage looper description
There are actually several different cabbage looper species, usually based on their favorite food. All cabbage looper larvae reach 1-1/2 inches long and end up pale green. They start out white but, as they feed, they turn green. They move in a classic ‘looping’ inchworm motion. The adult moth is brown.
Cabbage looper control
Unlike other inchworm larval forms, cabbage loopers are resistant to Bacillus thuringiensis (Bt). Luckily, they have many natural predators in the form of big-eyed bugs and parasitic wasps. Avoiding the use of broad spectrum pesticides can help these beneficial insects protect your crops. Hand-picking cabbage loopers can also reduce damage.
Bright yellow pests on milkweed? It’s oleander aphids!
Many of us have planted region-specific milkweed plants to support Monarch butterfly populations. What we didn’t know, was that we would also be inviting a new pest into our gardens: oleander aphids. These pests can suck the life out your milkweed plants before the Monarchs ever have a chance.
Oleander aphid description
Like other aphids, this species is small (1.5 to 2.6 mm), pear-shaped and soft-bodied. Oleander aphids, in particular, are bright yellow, with black legs, wings, and cornicles. Cornicles are tiny spikes on an aphid’s back that can excrete defensive fluid. [My dog did that once, after he got into some old pork bones. It wasn’t pretty.] Actually, these defensive fluids are cardiac glycosides that the aphids take from their host plants! Cardiac glycosides are known heart poisons. Luckily, these pests cluster on new stems and are easy to spot. And those defensive fluids won’t hurt you.
As much as I dislike aphids for their plant-damaging and disease-carrying capabilities, I have to give credit where it is due. These soft-bodied bugs really are amazing. Female aphids (and almost all of them are female) are viviparous and parthenogenetic. Wait! Come back! Let me explain. Viviparous means that offspring develop within the mother, the way we do. Parthenogenetic means fertilization by a male is not needed to produce offspring. Not like us. Most aphids do not have wings. But, when they become too crowded, or when a plant starts senescing (dying), some adult aphids emerge with wings. That would be something like all human beings being born 40% smaller, simply because we start running out of room and resources. Hmmm… But I digress. Let’s get back to aphids.]
Oleander aphid management
If you’re not squeamish, you can squish the aphids between your fingers. Or, if you see a stray lady beetle wandering around elsewhere in the garden, gently scoop them up and show them where the feast can be found. If those are not options, you can use a strong spray of water from the hose to dislodge the interlopers, or use insecticidal soap. On plants with heavy stalks, you can interrupt support for aphids from ants by painting the stalk with a sticky barrier. This won’t get rid of the aphids, but it will make them more vulnerable to their natural enemies.
Oleander aphid damage
Like other sap-sucking insects, oleander aphids pierce plant parts to tap into the phloem of the host plant. Think of it as diabetic mainlining. This nutrient rich food source blows through an aphid’s body, creating a sticky sweet residue called honeydew. Honeydew is a petri dish for bacterial and fungal growths, such as sooty mold. Also, the aphid tendency to feed in clusters stunts growth and deforms flowers and leaves, crippling milkweed and oleander plants. Vinca, periwinkle, and frangipani are also affected.
Katydids are cousins to crickets, grasshoppers, and mole crickets, and you might not want them in your garden or landscape.
There are over 250 different species of katydid in North America (over 2,000 species worldwide). The name ‘katydid’ refers to the sound made by males when they are trying to attract receptive females.
Katydids can be difficult to see. It’s not that they are small, because they aren’t. Mature katydids can range from 1/2” to nearly 5” in length! The difficulty lies in their resemblance to leaves and the fact that they are mostly nocturnal. During the day, they hide out in trees and shrubs, blending with the foliage. They tend to have a bright green, blade-like body, with large hind legs. They look a lot like flattened grasshoppers, but with extra long antennae (or ‘horns’). Very often, the only notice you will get that katydids are present is the damage they cause and a male’s strident chirp.
Katydids (Tettigoniidae) start out as oval-shaped eggs that are laid in rows, at the end of summer, in the soil and in host plant stem holes. These eggs often hatch out looking like tiny adult katydids with big heads and small wings. Nymphs of some species of katydid mimic spiders or leaf-footed bugs in their early stages of development to avoid being eaten. As they feed and grow, they shed their outer exoskeleton and go through several instars before reaching adult size. As summer nears its end, males start singing to attract females. Females use the volume and fluency of a male’s chirp to judge his fitness level. In order to ensure a healthy pregnancy for the female, male katydids provide their (temporary) mates with a ‘nuptial gift’ of sperm and highly nutritious food.
Katydids bite and chew many different plant parts, including leaves, stems, seeds, bark, buds, flowers, roots… okay, pretty much every part of a plant is vulnerable to katydid feeding. The damage often looks like it was caused by caterpillars or grubs. Citrus, peaches, pears, blueberries, apricots, plums, and pomegranates are just a few katydid menu items.
These pests are super fast, and difficult to catch. I use a butterfly net to catch them, and then I feed them to my chickens, who are very happy to help reduce my garden’s pest populations. Commercial growers often use spinosad to control katydids. I have read that katydids can inflict a painful bite or pinch, but I never give them the opportunity. Apparently, in Uganda, people eat katydids.
Katydids as thermometers
If you hear a katydid, you can estimate the ambient temperature using Dolbear’s law. According to Amos Dolbear’s 1897 calculations, you can count the number of cricket chirps that occur over a 15 second period and then add 40 to that number for a reasonable estimate of temperature. If you are using katydids for this experiment, it is suggested that you add 37, instead of 40.
If you hear katydids in the garden, go get your butterfly net and start hunting! These suckers can reproduce exponentially!
You can grow a surprising amount of food in your own yard. Ask me how!
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