Trails of slime and damaged leaves are clear signs of a slug or snail infestation in the garden. But, before we attack this problem, let’s take some time to learn more about these amazing creatures.
Slug & snail taxonomy
Slugs and snails are members of the mollusk phylum. The name mollusk evolved out of Aristotle’s name for cuttlefish, which meant “the soft ones”. Most mollusks are nothing more than a head attached to a foot. [Try picturing some of your friends that way!] They are included in the class known as Gastropoda, which means “stomach foot”. Unlike clams, which have two shells and are called bivalves, snails have a single valve (shell).
Slugs are simply snails without shells. There is also a group of gastropods that have a shell, but it is too small to retract into. These are called semi-slugs. Some snails have clear shells and are called glass snails. Aside from insects, there are more Gastropods on earth than any other animal. They are invertebrates, which means they have no backbone.
Snails and slugs excrete a mucous path in front of themselves as they travel. This mucous is a glycoprotein, similar to egg white, that smooths the ride and reduces friction. Imagine driving a car that fixed every pothole before you got to it! Of course, snails don’t win any speed records. In fact, they are the slowest animal, at 0.03 mph.
According to the Journal of Drugs in Dermatology, slug and snail slime helps reduce wrinkles, scars, dry skin, and acne, which is why it is included in many cosmetics! It also helps wounds heal faster and better. Some people allow a snail to crawl over a cut to help it heal. Just remember, slugs and snails can carry salmonella and other bacteria and a parasite that can cause meningitis, so wash your hands after handling them.
Slug and snail reproduction
Snails are hermaphrodites, which means they are both male and female, though not always at the same time. Snails mate in late spring and early summer after an extended courtship. Imagine that! How do you think snails court each other? They press their heads together!
It take 2-8 weeks for eggs to develop and 1-2 days for a snail to deposit 30-50 eggs in a hole dug in the ground. Three to four weeks later, depending on temperature and humidity, baby snails emerge. Now, if you have never seen a baby snail, you have really missed out. These translucent beings are perfection and elegance in action. Put your revulsion aside and grab a magnifying glass to really appreciate these tiny creatures. Seriously.
Slug and snail diet
Most land snails are herbivores (as gardeners well know!), but some are omnivores and some are predators. Snails eat a lot of calcium. The calcium is used to build their shell. The shell provides protection from the elements and some predators. Most of the calcium eaten by garden snails comes from dark, leafy greens, such as spinach and chard.
Not all land snails are edible, but most of them are. Raising snails for food is called heliciculture. People have been eating snails since prehistoric times. In France, the Helix pomatia snail is called “Petit gris” (little grey) and it is considered a delicacy. It’s close cousin, our American Helix aspersa snail, is larger, whiter, and just as edible. I haven’t tried escargot just yet, but if you do, let us know in the Comments!
Snails as pets
I recently learned that many people also keep snails as pets. Most apartment managers won’t even notice their presence and you never have to take them for a walk! Snails are very sensitive to noise, light, vibration, irregular feedings, unsanitary conditions and being touched. They are a very low maintenance pet, but they won’t do any tricks.
If you consider all snails around the world, they can range in size from less than a millimeter long to the 35” 40-pound marine giant, Australian Trumpet. The largest land snail, the Giant African Snail, is over 15” long and can weigh 2 pounds. The Giant African is commonly raised on discarded banana leaves and then consumed as food. [I think I'll pass.]
Snails have two pairs of highly mobile tentacles on the head. The larger pair features light-sensitive eyespots, while the smaller pair is used to smell and touch. Most land snails have lungs, but a few still breath using gills. Slugs and snails have a serrated tongue, called a radula, that looks a lot like a jagged shag carpet. They use the radula to rasp plant tissue free, before swallowing.
Slug and snail control
Now that you have a better understanding about these beasties, let’s get them out of the garden! Handpicking is highly effective if you do it often enough and at the right times. Since slugs and snails prefer moisture and darkness, predawn and nighttime are the best times for hunting. Use a flashlight and they are surprisingly easy to find. You can wear gloves, which makes picking up slugs easier and less yucky. Toss them in a plastic bag and trash them, or drop them in soapy water. You can also spray them with a 5-10% ammonia solution. I feed them to my chickens.
There are many predators that love to eat slugs and snails. Create a welcome habitat for these predators and they will find their way to your garden:
Concentrated garlic or wormwood solutions have been found effective against slugs and snails in commercial agriculture. Copper strips are advertised as effective slug and snail control, but I have never heard of them actually working. Bordeaux mixture (a copper sulfate and hydrated lime mixture) or copper sulfate alone can be brushed onto tree trunks to discourage snails.
Some gardeners introduce decollate snails (Rimuna decollata) into the garden as a control measure. Decollate snails hunt, capture and eat garden snails and slugs. Of course, introducing a non-native species isn’t without it’s own problems. These heavy feeders will eat many beneficial insects, as well. Decollate snails are banned in most California counties due to the risk to native species.
Slug and snail bait is a highly effective control method when used in conjunction with other plans of attack. Most people, however, use it incorrectly. At the first sign of irregularly shaped holes in leaves and telltale slime trails, lightly sprinkle bait around plants being eaten. Snails and slugs tend to return to the same feeding areas each day. Do not pour it into piles or apply heavily. There are a few different types of bait and you need to understand the risks associated with different ingredients:
It is a good idea to apply bait after watering. The moisture will encourage snail and slug activity and you won’t wash the bait into the soil.
Some people use traps to capture these nighttime feeders. You can leave melon rinds turned upside down to catch a fair number. Simply collect them in the morning and toss them to your chickens or kill the slugs and snails and add it to your compost pile. Beer traps sound great, but I’ve never had luck with them. I think it has something to do with my dogs drinking all the bait when I’m not looking…
You can grow a surprising amount of food in your own yard. Ask me how!