Stop getting rid of soil mites!
There are certainly plenty of bad mites: dryberry mites, Eriophyid mites, plum bud gall mites, and two-spotted spider mites are just a few. But not all mites are bad. Like their predatory cousins, European red mites, soil mites are your helpers.
Soil mites are extremely beneficial when it comes to releasing nutrients into the soil and controlling pest populations.
Conduct an online search for ‘soil mites’ and you’ll see dozens [millions] of sites telling you how to get rid of these pencil-point size arachnids. But getting rid of them is the last thing you should do. So, what’s so great about soil mites? Let’s find out!
What are soil mites?
Mites are arthropods. This means they have an external skeleton, a segmented body, and jointed legs. They are also arachnids, like ticks and spiders, but very tiny. If you were to take a sample of soil that weighed about the same as a bar of soap, 100 g give or take, you might have 500 mites from 100 different genera in that sample. These buggers are really tiny. With the naked eye, they might look like nothing more than little brown or white dots. But these little guys are important.
While there are over 20,000 known soil mite species, with an estimated 80,000 total, it is easier to categorize soil mites by what they eat. They can be herbivores or carnivores.
Plant-eating soil mites
To something as small as a ballpoint pen tip, fungi make a great meal. So do bacteria and lichen. These scavengers are abundant in most soils and they help plants gain access to nutrients. As these soil mites graze on the fungi and bacteria that grow on root surfaces, they poop out those meals in the form of plant food. They also shred decaying plant material as they feed on the bacteria and fungi clinging to those plant surfaces. Fungal feeding mites (Oribatei) look like little orbs. Also known as turtle mites, moss mites, and beetle mites, these soil mites are very tiny. Let’s call them moss mites. Moss mites range in size from 0.2 to 1.4 mm long. This means you could fit 10-90 of them across a dime, end-to-end, depending on the species.
Insect-eating soil mites
Other soil mites are predators. Predatory soil mites feed on microscopic garden pests, such as nematodes, fungus gnat and thrips pupae, springtails, other mites, and the eggs and larvae of other insects. Most predatory soil mites are 0.5 mm long, brown, and found in the top 1/2” of the soil. [Unfortunately, I could not find any freely available photos of predatory soil mites.]
While not all mites are good, soil mites are your friends in the garden.
Let them be, and be glad they’re around!
Pollinator gardens attract insects that pollinate your crops. They also tend to look lovely.
Similar to butterfly gardens, pollinator gardens use flowers and other plants to attract and provide for pollinators.
What are pollinators?
Pollinators are mostly insects, such as bees and butterflies, that carry pollen from one flower to another, resulting in fertilization and fruit production. Bats, birds, lizards, and even people can be pollinators, as well. Most pollinator gardens use insectary plants to attract these garden helpers.
What are insectary plants?
Insectary plants are those that provide food, shelter, and/or egg-laying sites for beneficial insects at various life stages. Those beneficials may be predators, pest parasites, or pollinators. The flowers that provide this service are usually globe-shaped, such as chives and onions, umbrella-shaped or flat-topped umbellifers, as in seen in carrot and cilantro plants that have been allowed to go to seed. Depending on your region’s pollinator species, the insectary plants suited to your area may be tall or short or both, but most are brightly colored.
As convenient as generic pollinator plants lists are, you will have a more effective pollinator garden if you take the time to identify pollinators native to your area. You can do this by searching online for “pollinators in [my town/state]”, and by contacting your local native plants society, Master Gardeners, and universities. Here, in California, the following native plants attract and provide for pollinators:
*Those marked with an asterisk are recommended by the Xerces Society for Invertebrate Conservation. In addition to adding pollinator plants to your landscape, there are other actions you can take to create a more successful pollinator garden.
While you generally want to keep salt as far away from your garden as possible, there are exceptions. Using a damp salt lick to provide minerals and moisture for bees and butterflies is one of those exceptions. If you have an area that stays damp, simply add salt or wood ashes to the mud. Otherwise, you can put out a dish of slightly salty water. Sea salt contains more important micronutrients than table salt, but table salt is better than nothing. Just remember that salt will damage nearby plants.
Plant for variety
Pollinators are active, in most regions, from early spring through late fall. Ensuring that your landscape includes a variety of insectary plants during that time frame will go a long way toward attracting and supporting valuable pollinators. That variety includes clumps of native plants, suited to your microclimate, and some night-blooming plants that provide for moths and bats.
I use a spreadsheet that lists months across the top and a rainbow of colors down the side to document what is blooming, throughout the year, in my landscape. I add to it as I notice or add new plants. This way, I can see when there are gaps in flower production. Since those flowers provide pollen and nectar, the more I have, the better off my pollinators will be. [The file is too large to share here, but you can email me if you would like a copy.]
Evolution is a relatively slow process. Many of our modern hybrids, especially those with ‘doubled’ flowers, have had their fragrance, nectar and pollen bred right out of them. They may look nice, but that’s all they have to offer.
Quit the chemical habit
Broad-spectrum herbicides, insecticides, fungicides, and pesticides have no place in your pollinator garden. Even those advertised as “safe” can disrupt the breeding, feeding, and existence of beneficial insects. They are probably not very good for us, either. Instead of chemicals, practice least damage Integrated Pest Management (IPM). If you absolutely must use chemicals, apply them at night, when most pollinators are not active.
Dead limbs can be good
Dead branches and dead trees provide nesting sites for native bees. Stumperies also create habitat and food for a variety of birds and other insects. Just make sure your dead tree does not create a safety issue. Trees are extremely heavy.
Your hummingbird feeder provides nectar for far more than just hummingbirds. Chickadees, wrens, and orioles may also enjoy a sweet sip every now and then. And so will many pollinators. The 1:4 sugar to water ratio used in hummingbird feeders is fine for many beneficial insects, too. Just be sure to wash your hummingbird feeder with hot, soapy water once or twice a week to avoid mold and the spread of disease.
Setting aside just a little space in your landscape for a pollinator garden can profoundly increase the number of butterflies, native bees, and other beneficials you see each year. And they could really use our help these days.
How many butterflies did you see in the past year? Not very many, right? You can attract a surprising variety of butterflies to your landscape with a butterfly garden.
Back in my hitchhiking days (the 1970s), I saw millions of butterflies along the Interstate. They would litter the side of the freeway and create colorful clouds in the air. In my own insect-friendly yard, however, I saw no more than a dozen butterflies last year. What happened?
Threats to butterflies
Butterflies have been around for 56 million years, but times are hard. Habitat loss, pollution, pesticide use, invasive species, rising temperatures, and interruptions in their food web all make life difficult for butterflies. Butterflies are particularly hard hit because many of them rely on a single plant species as hosts for their eggs and offspring.
Here, in San Jose, California, we have 144 species of native butterflies. Sadly, we also have the highest density of endangered butterfly species in the nation. Some of the most threatened California butterflies and their host plants include:
Imagine what would happen if everyone added just one butterfly-friendly plant to their landscape.
Most of the plants used in butterfly gardens are insectary plants. Insectary plants are those with the color, shape, and height that appeal to butterflies and other beneficial insects. Common insectary plants include the following:
Members of the sunflower family (Asteraceae) also make good insectary plants. The problem with these generic lists is that many of these plants are non-natives, which can cause problems. Even though these plants provide nectar and pollen for adults, they can actually devastate local butterfly populations because the adults see food for themselves and lay eggs nearby. When those eggs hatch, the larvae have nothing to eat. Put simply, these might or might not be the plants your butterflies need. Or they might be perfect.
I cannot tell you which plants, specifically, to include in your butterfly garden. This is because each region has its own indigenous butterfly population. To find out what is native to your area, conduct an online search for “butterflies native to [your town]. The results may surprise you.
Once you have a list of indigenous butterflies, you can track down their host plants. Host plants are those that will provide the pollen and nectar needed by adult butterflies and the leaves needed for egg-laying and caterpillar feeding. Armed with this information, you are ready to design your butterfly garden.
Planning your butterfly garden
Your butterfly garden doesn’t need to be big or formal to be effective. You can scatter host plants throughout your landscape, if you like. Or you can create an elegant parterre. It’s up to you. Butterflies do use sunlight to warm themselves, so south-facing areas are preferable, as are areas protected from wind. A water feature, such as a bird bath or fountain, can help your butterflies stay hydrated. Rocks, for basking, are always appreciated.
There is also nothing saying you have to install plants specifically for endangered species, although it would be nice. The important thing is to get the correct plants in the ground and helping them to thrive.
Adding a butterfly garden to your landscape does not take a lot of effort on your part, but it can make a huge difference for the butterflies. It will also increase the biodiversity in your garden, making it a healthier environment. Other beneficial insects will also be attracted to these plants. These beneficial insects might be pollinators, predators, or they may parasitize insect pests.
And the flowering plants look lovely.
Did you know that some adult butterflies also eat carrion, rotting fruit, and tree sap, while the larvae of some butterfly species eat ants and other insect pests? I didn’t either.
Now we know.
Stink bugs have shield-shaped bodies and most of them are plant pests. The rough stink bug, however, occasionally eats pests!
As true bugs, rough stink bugs (Brochymena sulcata) are cousin to aphids, leafhoppers, and scale insects. There are several different subspecies of rough stinkbug and none of them are 100% beneficial.
Rough stink bug identification
Their classic stink bug shield-shaped body is rather flattened and a bumpy mottled grey and black. This coloration makes them blend in well with bark. They average 1/2” to slightly more than 3/4” in length.
Do not confuse rough stink bugs with brown marmorated stink bugs (Halyomorpha halys.) or consperse stink bugs (Euschistus conspersus). Brown marmorated stink bugs are relatively new to California and pose a serious threat to gardens and orchards. They have white bands on their antennae and legs, the front of the head is more blunt than other species, and the thorax is smooth. Consperse stink bugs have no banding on the antennae, but dark spots on the legs, the thorax is smooth but somewhat convex, and this species is smaller than others.
Rough stink bug diet
Like other stink bugs, a rough’s favorite foods are plant-based. While other species prefer fruits and vegetables, the rough stink bug diet is predominantly the leaves and developing seeds of ash, boxelder, walnut, willow, and many other trees. The thing that makes the rough stink bug beneficial is that they also feed on caterpillars and leaf beetle larvae.
Rough stink bug lifecycle
Rough stink bugs spend their winters hidden under logs or the bark of trees. They may also try to get in your home. If they do, keep in mind that their name is an important clue. If you vacuum them up or squash them in your home, there will be consequences. Stinky ones. Instead, sweep them up with a dustpan and drop them into a container of soapy water or feed them to your chickens.
As spring temperatures rise, rough stink bugs become active again and start looking for a mate. Mated females lay clusters of 10 to 20 white, elongated eggs before they die. Two weeks later, the eggs hatch and pale colored nymphs emerge and begin feeding. There is one generation per year in most regions.
In most cases, getting rid of stink bugs is a good idea. The rough stink bug is an exception.
Trichogramma wasps are small but mighty.
These microscopic parasitic wasps protect an astounding collection of edible plants. It might be easier to list those they do not protect, but your almond, apple, avocado, beet, blackberry, blueberry, celery, cherry, corn, cotton, grape, orange and other citrus, legume, papaya, peach, peanut, pear, plum, pumpkin, quince, squash, strawberry, tomato, walnut, and zucchini plants and trees are better off when Trichogramma wasps are in the neighborhood. These tiny wasps protect your plants from damage by parasitizing the eggs of these garden pests:
Parasitic wasps lay their eggs in many common garden pests. This group of beneficial wasps includes braconids, chalcids, Goniozus wasps, ichneumon wasps, and Trichogramma wasps.
Female Trichogramma wasps seek out the eggs of pesky moths and butterflies and sawflies to use as nurseries for her own eggs. When she finds one, the first thing she does is drum on it with her antennae and ovipositor to see if it has already been used. Drumming also helps her determine how big and useful the host egg is. This dictates how many eggs she will insert.
After being inserted into a host egg, the wasp egg develops, pupates, and then hatches, after which it feeds on the contents of the host egg. This turns the host black. If you use a hand lens and see a healthy white host egg with a chewed hole, it means the egg was not parasitized and a healthy (destructive) caterpillar emerged instead.
Trichogramma wasp species
Unless you are a scientist with a very powerful microscope, you will never see a Trichogramma wasp. At 1/25“ to 1/50” long, you could fit 20 to 40 of them nose-to-tail across a dime. If you could see them, you might be struck by the simple beauty of a minuscule yellow wasp with red eyes. Or, you might not. There are over 200 species of Trichogramma around the world.
Before you order a shipment of Trichogramma wasps as a biocontrol, keep in mind that different species of Trichogramma parasitize different hosts. It is important that you order from a reputable seller to avoid releasing a threat to other beneficial insects into your garden. When reading product descriptions, take the time to do a little research before you buy.
Trichogramma wasp eggs are shipped as larvae in host eggs that have been glued to cards. If you buy Trichogramma wasps for release, these tips will give them the best chance at being successful:
Keep in mind that Trichogramma wasps will not kill all the pests they come across. What they do is provide one piece of an integrated pest management program that uses natural processes to reduce the overall impact of pests, rather than spraying chemical poisons on your food.
Watch out for the yellow jackets and hornets, leave mud daubers and paper wasps to go about their business, and add some insectary plants to attract and provide for beneficial wasps, such as the Trichogramma.
Goniozus wasps can sting, but you’ll never have to worry about that.
Like many other parasitic wasps, adult Goniozus wasps mostly feed on nectar, sap, and other sweets. The benefit they provide is that they also parasitize pests of almond, apple, citrus, fig, pistachio, walnut, and coconut trees, as well as blueberries, blackberries, grapes, and strawberries.
Navel orangeworm, obliquebanded leafroller, and light brown apple moth caterpillars are favorite egg-laying hosts, giving Goniozus the common name of navel orangeworm wasp. Personally, I prefer Goniozus - in my mind, it’s the Gonzo wasp. These garden helpers also use banana scab moths and several insect pests associated with galls as hosts.
Goniozus wasp description
There are 20 different Goniozus wasp species, and they all look like tiny flying ants. Walking through the garden, you may simply see a very small, shiny brown or black wasp-waisted insect. Most insects who fit that description are beneficial, so resist the urge to swat them away. Instead, take a moment and see if you can tell what they are up to.
Similar to cuckoo bird species, which lay their eggs in the nests of other birds, Goniozus wasps are also known as cuckoo wasps because they lay their eggs in the bodies of other insects.
Adult females use their stinging ovipositor (egg-laying tube) to paralyze their victims, injecting hosts repeatedly with venom. The venom of some Goniozus wasps is permanent, but not all. In those cases, the venom only lasts half an hour or so, so she has that much time to transport her victim, mostly by dragging the much larger host, to a good hiding spot. If necessary, she will continue to inject venom over several hours, if that’s how long it takes to get where she needs to go.
Once tucked safely into a crevice somewhere, some females will feed on the juices of said caterpillar over the next few days, aiding in the development of her eggs. This does not always kill the host. In some cases, the host simply walks away, a little worse for the wear, until the eggs hatch and begin feeding from the inside out.
Goniozus larvae go through several developmental stages over the next 2 or 3 days, attached to their host, ultimately spinning tiny cocoons around themselves before reaching adulthood. Apparently, Goniozus wasps have been observed paralyzing far more hosts than they can possibly use for egg-laying. No one knows why.
How to attract Goniozus wasps
Beneficial parasitic wasps can be attracted to your garden with insectary plants. Insectary plants provide the food and shelter needed by these garden helpers. Most insectary plants feature umbrella-shaped flowers commonly seen in carrot, dill, cumin, mint, and cilantro, or globe-shaped flowers, such as chives. Allowing these plants to go to seed not only attracts beneficial insects, but seeds then create perpetual, edible crops. Other insectary plants include cosmos, sweet alyssum, yarrow, dandelions, and borage.
Adding these useful plants to your yard looks nice, too!
Unlike beneficial parasitic wasps, hornets attack honey bees, steal honey, invade bat houses, girdle branches, and ruin summer picnics.
So why would we want to tolerate hornets in the garden? What good can they do? Let’s find out!
Worldwide, there are 22 hornet (Vespa) species, including:
There are also 3 species of nocturnal Asian Provespa, which are not actually hornets.
Despite their name, bald-faced hornets (Dolichovespula maculata), commonly seen in California, are not true hornets, either.
There is only one true hornet found in North America: the European hornet (Vespa crabro). Introduced in the 1800s, this hornet is now found throughout the U.S.
Hornets are highly social insects. They live in large colonies, housed in papery hives, that are commonly built in dark crevices, such as dead tree trunks, under house eaves, and in your garage. Hives are made up of interconnected brood cells. Both the queen and workers can lay eggs. Fertilized eggs laid by the queen develop into sterile females, called ‘gynes’ while eggs produced by workers develop into males, called drones. Drones mate with the queen during ‘nuptial flights’. As a result, a hornet’s nest is largely populated by two nearly distinct gender-dictated populations. Workers care for the eggs as they move through larval and pupal stages, ultimately emerging as adult hornets.
Hornets and yellow jackets are both types of wasps, though yellow jackets tend to be smaller, with more yellow and black, while hornets tend toward more black and white or yellow and brown coloration.
Most hornets average 3/4” to 1”, while queens can be 1-1/2” long. If you look closely, you might be able to see that a male hornet abdomen has six segments, while females have seven segments and a stinging ovipositor.
Hornet stings and allergies
Like many other stinging insects, hornets become aggressive when they feel accosted (swung at, stepped on, sat on, that sort of thing), or when they believe their food supply or the colony are threatened.
Hornet stings are more dangerous to humans that other insect stings because they contain higher concentrations of acetylcholine. Hornet stingers are not barbed and can be reused many times. Also, when one hornet stings you, it releases chemicals that tell other hornets to sting you, as well. These same chemicals are also released when you kill a hornet or spray a hornet’s nest with poison, so be forewarned.
If you are allergic to stinging insects, you should always carry antihistamines or an EpiPen with you. Signs of an allergic reaction include shortness of breath, swelling of the face, lips, or throat, severe itching, weak or racing pulse, nausea, wheezing or gasping. If any of these symptoms occur, get medical help immediately. Call 911, grab a family member, or a neighbor right away. These symptoms can quickly escalate into a life-threatening situation. Otherwise, follow these steps to ease your temporary pain:
You can also take aspirin or acetaminophen to ease the pain, just be cautious about mixing medications, as that can cause yet another medical problem. Generally speaking, you are going to feel really miserable for 30 to 45 minutes, moderately uncomfortable for the rest of the afternoon, and you may experience discomfort for a week or so. You may also want to apply hydrocortisone or calamine lotion to the area. Pastes made of baking soda or colloidal oatmeal can also sooth the area. If you haven’t had a tetanus shot in the past 10 years, that can be a good idea, as well.
So, why would we want hornets in the garden?
Adult hornets feed on sweets, such as fallen fruit, sap, and your lemonade. They also collect insects for their larvae. This is part of the reason why they cause us so much grief during picnic season. From a hornet’s point of view, it is simply defending a food source when it refuses to back down from your burger and fruit punch. In addition to your picnic, European hornets commonly chew up beetles, dragonflies, grasshoppers and crickets, katydids, locusts, mantises, moths, and other wasps. This pulp is then taken back to the colony, where it is fed to larvae in the nest.
If you start having a hornet problem while dining outside, you can reduce the chance of stings by placing a plate of meat and fruit somewhat away from the picnic table.
If hornets become a problem around your home, try excluding them before poisoning them. Those chemicals tend to create more problems than they resolve.
There is far more to wasps and hornets than you might expect.
This group of insects is massive and it contains many beneficial insects. You may not be familiar with chalcidoid wasps, but odds are pretty high they’ve been working hard in your garden all along.
The chalcidoid superfamily of wasps contains 22,500 known species, with an estimated 500,000 species yet to be named. One of those families in particular, the Chalcididae, gives us chalcid wasps. And figs.
Chalcid wasp description
Ranging from only 1.5 to 0.75 mm (1/50 - 1/100”), you could fit 12 to 24 chalcid wasps nose-to-tail across a dime, so you probably will never see one. If you could see them, you would understand how they got their name. The word ‘chalcid’ comes to us from the Greek word for ‘copper’ because most chalcid wasps are a metallic bronze or copper color, though some species are metallic blue or green, and some are the more classic black and yellow variety.
Beneficial chalcid wasps
Most chalcids are parasitic wasps. They lay their eggs in several common garden pests. When the eggs hatch, larvae feed on the host insect before pupating into adult wasps. [I know, it’s sounds awful.] Those hosts include the eggs and larvae of flies, beetles, moths and butterflies, some spiders and nematodes, and true bugs. Since true bugs (Hemiptera) include aphids, leafhoppers, spittlebugs, thrips, whiteflies, and scale insects, I am all for more chalcid wasps! [Plus, I love figs!]
Figs and tiny wasps
While most chalcidoid wasps parasitize all those pests, a handful of them are phytophagous, which means the larvae hide and feed in stems, galls, seeds, and flowers. Fig flowers, in particular, are hidden clusters found inside a hollow structure called a syconium. Fig pollination is usually completed by tiny specialized wasps, such as chalcid wasps.
But, not all chalcids are good.
Chalcids as pests
Other phytophagous chalcids are not so helpful. These tiny wasps are pests because they lay their eggs in seeds. When those eggs hatch, larvae eat the seeds of pistachios and alfalfa, among others, creating burrows and allowing fungal and bacterial diseases a point of entry.
In many cases, sticky barriers can be used to reduce the damage caused by these pests. Most chalcids, however, are beneficial.
You can attract chalcid wasps to your garden by installing insectary plants, such as yarrow.
Wasps may have a bad reputation, but there are beneficial wasps, and ichneumon wasps [pronounced ick-NOO-mon] are one of those Good Guys. Well, mostly.
Ichneumon wasps are parasitic wasps and they have been around for over 15 million years.
There are somewhere between 60,000 and 100,000 different ichneumon wasp species in the world, with 5,000 species in North America. Clearly, with those numbers, there is significant variety in appearance.
Ichneumon wasp description
Like other wasps, the ichneumons have a narrow body and an even narrower waist. Some females have an especially long ovipositor, which is often mistaken for a stinger. Ranging in length from 1/10” to over 5” long, they can be black, brown, yellow, or some pattern combination of those colors. These wasps have 16 or more segments in their longer than average antennae. Ichneumons are solitary wasps.
Common ichneumon prey
Adult ichneumon wasps eat little or nothing. Their larvae, on the other hand, are voracious feeders of beetle, butterfly and moth, wasp, ant, fly, and sawfly larvae and pupae or chrysalises. This is what makes ichneumon wasps so helpful in the garden. They also parasitize beet armyworms, some spiders, and wood-boring grubs.
Some ichneumon wasps do this by using their long antennae to detect prey, then inserting the ovipositor into the wood, plant, or soil, to strike their prey, piercing its skin and inserting an egg. Other ichneumon wasps crawl down the stems of aquatic plants to inject eggs into water-dwelling insects. Yet another ichneumon is the parasite of a parasite, making it a hyperparasitoid. This ichneumon lays its eggs in moth-eating ant larvae. She emits chemicals that confuse the ants as she does her deed.
Ichneumon wasp lifecycle
Most parasitic wasps lay their eggs on, in, or near their prey, but ichneumon wasps kill their prey outright and then lay eggs. When the eggs hatch, larvae feed on the host’s body. After hatching and eating their host, ichneumon larvae spin cocoons and pupate in or near the exoskeletons of their first meal. When they emerge from their cocoon, they are adult wasps who go in search of a mate.
These garden helpers do not sting and they are worth their weight in gold, so check before swatting at something just because it might be a wasp. [Swatting at wasps is usually a bad idea, anyway…}
One of the best ways to attract and provide for beneficial ichneumon wasps in California is to plant coyote brush (Baccharis pilularis) and to maintain hedgerows.
The ashy grey lady beetle is both stylish and deadly.
We’ve all seen the red domed lady bugs of popular culture, with their shiny black dots, but what about the black lady beetles with red dots?
There are only four types of black lady beetles with red spots. The twicestabbed lady beetle (Chilocorus orbus), Axion plagiatum, Chilocorus kuwanae, and the ashy grey (Olla v-nigrum). Unlike other lady beetles, however, the ashy grey comes in two forms: dark and tan, which can be changed at will!
Ashy grey lady beetle description
Ashy grey lady beetles are sometimes ashy grey or tan, with black spots. At other times, they are black with red spots. Before they reach their domed adulthood, ashy grey lady beetles look more like tiny alligators with yellow spots.
And before that, as pupae, they look like little orangish-yellow nubs. As eggs, they look like clusters of yellow, usually found on the underside of leaves, close to prey.
Ashy grey lady beetle prey
While ashy grey lady beetles do feed on the eggs of butterflies and moths, the lion’s share of their diet consists of aphids and psyllids. Since aphids and psyllids are both disease-carrying, plant-sucking pests, we can use as many lady beetles as we can get in the garden.
To attract ashy grey lady beetles and other beneficial insects to your yard, avoid using broad spectrum pesticides, provide fresh, clean water, and plant a variety of insectary plants, such as dill, lavender, chives, mint, tansy, and yarrow, just to name a few.
How many different types of lady beetles are in your garden?
Rove beetles are a family of mostly elongated predators that protect your plants against a great many garden pests.
There are over 63,000 different species of rove beetles (Staphylinidae), making them the largest beetle family in the world. There are approximately 4,360 species in the United States. Rove beetles have been around for over 200 million years and it may take another 200 million years to sort out this particular family tree. Currently, there are over 30 subfamilies of rove beetle, and scientists are still trying to sort it out.
However these tiny beetles end up being related, the majority of them pack a wallop when it comes to devouring many common garden pests.
Also known as trash beetles, these beneficial insects are often found in leaf litter, mulch, under loose bark, and around fallen trees. They may also be found in bird nests and rodent burrows where they presumably feed on fly and flea larvae. This huge family is extremely diverse. Some have evolved to live within caves, while others prefer living in mushrooms.
Rove beetle description
As you might expect from a family of this size, rove beetles come in a variety of shapes and sizes. Most of them are very small, averaging only 0.08 to 0.30 inches long, but they can range from 0.03 to 1.5 inches in length.
Most rove beetles have a narrow body that can squeeze into tiny crevices in search of prey and shelter. Rove beetles can be black to brown, yellow to red, and even an iridescent blue-green. They have thread-like antennae with 11 segments; some of them have little knobs at the ends. Most rove beetles have short wing covers (elytra), which means you can see several abdominal segments. Many rove beetles look like a multicolored earwig without its pincers, but certainly not all.
Rove beetle eggs are typically white, but can be spherical, pear-shaped or oval. Flattened larvae may have a distinct ‘neck’ or an armored head, though not all exhibit those characteristics. Pupae can be hard, dark colored cases, or naked white grubs, depending on the species. Adults tend to be long-lived.
Many rove beetle species produce secretions. Some of these secretions help repel water, allowing clumsy insects to recover from falling into water, while other secretions can be particularly toxic. One of those toxic secretions, found in the Paederous group, is transferred from mother to offspring, at birth, providing protection against spiders. This secretion can cause skin irritation and it can damage your eyes. It is the most powerful animal toxin that we know of, but scientists are learning how to use it to heal lesions and treat cancer.
Rove beetle diet
Adult rove beetles eat mites and small insects, as well as root maggot eggs and larvae. Rove beetle larvae also parasitize root maggot larvae. The rove beetle diet is a Who’s Who of garden pests, including:
If eating all those pests weren’t reason enough to appreciate rove beetles, it ends up that adult rove beetles also pollinate cherimoya fruit.
You can help the rove beetles in your garden by avoiding the use of broad-spectrum pesticides and insecticides, and by maintaining permanent areas planted with bunch grasses or other low-growing perennials to provide year-round habitat for these tiny hunters.
What types of rove beetles have you seen in your garden?
We’ve all heard about ladybugs, but what about twicestabbed lady beetles?
Common ladybugs, or lady beetles, have the classic red half-domed shape, stubby antennae, and multiple black spots. This particular lady beetle has a black domed shape with two distinct red spots, hence the name. If you turn one over, their undersides are red or yellow.
Twicestabbed lady beetle description
Twicestabbed lady beetles (Chilocorus orbus) are only one of four black lady beetles with red spots. The other three are Axion plagiatum, Chilocorus kuwanae, and ashy gray lady beetles. All four species are beneficial predators, so it isn’t critical to be able to tell them apart. [The ashy gray lady beetle has a unique ability to change its color from gray to red, but we will discuss that another day.]
Twicestabbed lady beetle larva have the same bristled, elongated, alligator shape of other lady beetle larvae, but are more grey than black. Adults are 1/10 to 15 of an inch long.
Twicestabbed lady beetle diet
Twicestabbed lady beetles feed predominantly on adults and larvae of scale insects. Their diet includes armored scale on avocados, brown soft scale on citrus, European fruit lecanium on cherry, San Jose scale on pear, and more. You will rarely see twicestabbed lady beetle larvae because they spend most of their time hidden under scale insect domes, feeding. Eggs are even less likely to be seen, at 1/32” in length. Eggs may be laid singly or in clusters.
Feeding is normally done by piercing the victim and sucking out their innards. Older lady beetles also bite and chew their food.
As with other lady beetle species, it does no real good to buy them. If they don’t like what’s on the menu in your garden, they will simply fly away. If you make your garden appealing to lady beetles, they will find you.
This means providing fresh, mosquito larvae-free water. [Use mosquito dunks in all standing water.] Lady bugs also eat pollen, so planting a variety of flower colors and shapes may attract them. Allowing dill, cilantro, and fennel to go to seed provides a ready food source for both you and lady beetles. Also, avoid the use of broad spectrum pesticides and insecticides.
How many different species of lady beetles are in your garden?
No, it's not a flying snake.
Introducing another beneficial insect on the California garden scene: the snakefly.
I don’t know why they call it a snakefly. It doesn’t look like a fly or a snake. Apparently, snakeflies are native to the western half of North America, as well as Europe and Asia. Until yesterday, I had never heard of snakeflies. Let’s see what we can find out!
The first thing I learned about snakeflies is that they are considered living fossils, having remained relatively unchanged for over 140 million years.
Snakeflies (Agulla adnixa) have long, thin bodies with lifted torsos (prothorax), large eyes, extended mouthparts (mandibles), relatively long antennae, and a long, thin backend. Adults are reddish brown and can be 1/2 to 1” long. All four wings are transparent, and longer than the body, similar to lacewings (except that snakefly wings are covered with black veins). The long backend is not a stinger. Instead, it is an ovipositor, or egg-laying tube.
Larvae have squishy bodies, and the head and first segment are hardened (sclerotised), but they look like a cross between an earwig and a ladybug larvae. [Sorry, but I couldn't find any free-to-use photos.] Snakefly larvae have 3 pairs of true legs, and, you won’t believe this: Snakeflies have an adhesive strip on their abdomens that allows them to move up walls and trees!
Eggs are deposited in the soil, where they are able to absorb soil nutrients to help them grow and develop. When they hatch, larvae stay in the soil or move to the bark of nearby trees. There, they feed on soft-bodied pests, such as grubs and caterpillars, as well as the eggs and larvae of many garden pests. Snakefly larvae go through as many as 10 moltings before reaching adulthood. This process can take 2 to 6 years. Next, after temperatures reach 32°F, the larvae enter a pupal stage. Unlike other insects, the snakefly pupa is mobile, leaving its pupal cell for day trips or to relocate. The pupal stage is temperature dependent, lasts a few days to 3 weeks, upwards of 10 months. [This is one long lived insect!]
Adults snakeflies are very territorial as they feed on insects, such as mites and aphids. [Yay!] It is also believed that they occasionally nibble on pollen.
Snakeflies court one another with cleaning rituals. You may see them practicing their flirting skills by cleaning their legs and antennae when alone.
Have you seen any snakeflies in your garden? Let us know in the Comments!
Before you swat that tiny wasp away, take a closer look.
It may be one of the Good Guys.
Like other ichneumon wasps, Exochus females insert their eggs into the larval stage of many leaf rolling caterpillars, such as the orange tortrix and the obliquebanded leafroller. The eggs then hatch inside the caterpillar and begin feeding. You can see video of an Exochus female attacking a caterpillar here. The video is bit long, but fascinating.
These tiny wasps serve us well in the garden, so avoid using any broad spectrum pesticides and let nature take its course.
Many slender-bodied insects, such as thrips and leafhoppers, are garden pests. Damsel bugs are an exception. Damsel bugs are predators. And they are very quick.
Damsel bug actually refers to most of an entire family of insects (Nabidae). Most damsel bugs are Nabis species.
Damsel bug description
Damsel bugs are true bugs (Hemiptera), which makes them cousin to many of their favorite foods. Whereas the “beak” (rostrum) is used by most true bugs to pierce plant tissues and suck sap, damsel bugs use their beak to inject digestive enzymes into victims. In either case, the beak is usually held under the body when not in use.
Damsel bugs have soft, slender bodies that may be brown, gray, yellowish, reddish brown, or tan. Adults are 3/8- to 1/2-inch long. They have long legs and long antennae, and may be confused with equally beneficial assassin bugs. Like assassin bugs, some damsel bugs can and will bite. They are, after all, predators. Medically speaking, as far as I know, damsel bug bites are harmless.
Damsel bug lifecycle
Young damsel bugs, or nymphs, look a lot like adults, which means they go through an incomplete metamorphosis. They have 5 developmental stages, or instars, before reaching adulthood. This process takes approximately 50 days. Adult females hide eggs by laying them inside plant tissue. Damsel bugs are most active in the Bay Area mid-June through mid-August, but they overwinter in ground cover and winter crops, such as alfalfa and many legumes. Remember, just because you don’t see them doesn’t mean they aren’t there.
Damsel bug prey
Like lady beetles and praying mantis, damsel bugs are generalists. This means they will eat whatever they can hold onto long enough to eat. Very often, those meals are aphids, armyworms, small caterpillars and caterpillar eggs, fleahoppers, leafhoppers, lygus bugs, mites, proba bugs, spider mites, and thrips. (Hooray for damsel bugs!) Of course, they will also eat beneficial big-eyed bugs and minute pirate bugs, and occasionally they will even eat plants, but their net result to the garden is still very positive.
In one study, it was estimated that a single adult damsel bug eats 42 moth larvae, 24 lygus bug nymphs, or 5 aphids every day. The same study estimated that a peak population of damsel bugs (283,000 bugs per acre) could consumer 12 million moth larvae, 6 million lygus bug nymphs, 1 million aphids, or some combination of those and other prey, every 24 hours. That’s some significant garden protection!
If you keep a hand lens in your pocket, you may be able to see a damsel bug up close one day.
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. These ground beetles will occasionally eat seeds and organic litter, but, as their name indicates, they prefer meat to vegetables. In fact, adult predaceous ground beetles can eat their body weight in food each day
So, the next time you see a black beetle running across the patio, look for fat legs and eyebrow ridges before squashing it!
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 ear 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.
California bumblebee species
There are over 250 species of bumblebee worldwide and 26 species in California. There used to be 14 native bumblebee species in the Bay Area. Now there are only a handful. This is especially unfortunate when you realize that native bumblebees are responsible for pollinating 42% of all native California flowering plants, according to UC Davis entomologist Robbin Thorp. Currently in the Bay Area, you may see:
These bumblebee species have not been seen in the Bay Area 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 comprehensive guide to California bumblebees and a nice poster of western bumblebees with dietary notes. You can also learn more about bumblebee conservation from the Xerces Society.
You can grow a surprising amount of food in your own yard. Ask me how!