Snails as Garden Pests
Of all the pests that can enter a greenhouse, arguably the most repulsive is the common garden snail. (Snails are often confused with slugs since both have the same general appearance and both leave the characteristic slimy trails we are used to seeing. However, snails have a shell, slugs do not.) The common brown garden snail, which was originally brought to the United States from France, is the same type of escargot that is served in specialty restaurants. They were introduced to California in the 1850s by European settlers who thought snails would be a familiar food source. But, when the effort was less successful than they had expected, the idea was largely dropped.
When they were no longer cultivated as food crops, the snail populations grew and spread and are now a common pest in gardens, flower beds and greenhouses. In order to get an idea of how prolific brown snails can be, consider this: each adult snail can lay 80 eggs as often as six times per year, so effective control of snails requires constant vigilance.
Snails are nocturnal and feed on organic matter in the soil, bark from trees, and especially on vegetation. Nearly anything growing in a vegetable or flower garden can be consumed. In particular, snails like tender foliage, young seedlings, herbaceous plants and ripening fruit that grows near the ground. They have also been known to feed on avocado and citrus foliage and fruit. Snails feed on both living and decaying plant material. The leaves of affected plants will have irregular holes with smooth edges, and new fruit and young plant bark can be damaged as well.
Snails feeding on cultivated plants may become serious pests. Enormous populations can sometimes become established in citrus groves and cause serious damage to leaves and fruit. They also cause economic damage to truck crops and ornamental plants. Large numbers of snails are a nuisance around homes, greenhouses, nurseries, outbuildings and sheds.
Smals as Predators in the Garden
Not all snails are pests. There is a predatory snail called decollate (Rumina decollate), or cannibal snails, that keep the brown garden snail under control since they devour brown garden snail eggs and small snails.
Decollate snails are easy to distinguish from the brown garden snails. Brown garden snails have a rounded shell, whereas decollate snails have a cone shaped shell.
While decollate snails work well as a biological control of brown snails, it is important to keep in mind that they can take years to become established. Moreover, decollate snails can also feed on young, tender seedlings, small plants and flowers—though not as heavily as the brown garden snails.
So, if you can take some bad with the good, then decollate snails might be the control you are looking for. Decollate snails are available for sale through specialty shops and mail-order catalogs.
Snails as Food
The only danger in eating garden snails is when they have ingested poisons for snail control. In order to eliminate this danger, wait six weeks after poison control material has been applied to gather the snails.
Larger mature snails have tastier meat than younger smaller ones and are easier to remove from their shells. Snails should be collected when they are about the size of peas, or about 10 days after hatching. Place them in a fine mesh cage and feed with cornmeal and chopped lettuce or other greens until they are large enough—about one to 1.5 in. in diameter.
In order to make brown snails ready for consumption, the gathered snails must be purged of any off-flavor or toxic materials from previously eaten food. To do so, place about 0.5 in. of damp cornmeal in the bottom of a container, such as a plastic basket, metal pan or crock.
Place the snails in the container and cover with a ventilated or screen top, such as a cheesecloth or nylon netting that would allow for air flow as well as visibility. Weight the cover along the sides with bricks or tie it securely so the snails do not escape. Place the container in a cool, shady area and let the snails purge themselves by eating the cornmeal for at least 72 hours.
If you wish to keep them there longer, replace the cornmeal every other day to prevent it from molding and souring. The snails feed and then crawl up on the side of the container to rest; take note of this movement as only active snails should be used and inactive snails on the bottom should be discarded. Once purged, the snails should be washed thoroughly with cold running water to remove the cornmeal from their shells.
Heat a large pot of boiling water with bay leaf and then plunge in the live snails. Simmer about 15 minutes. Drain well. With a wood pick or pointed knife, pull the snail meat from the shell. If desired save shells for later use. Remove and discard the dark-colored gall, a quarter-inch protrusion on the tail end where the snail is attached to the shell. Rinse the snail several times under running water.
The snail meat is then ready to be used in a recipe or packaged and frozen for later use. To prepare the empty shells for use, boil them in boiling soda water (use a ¼ tsp. baking soda per pint of water). Drain and rinse in cold running water, then dry.
Controlling Snails in Your Garden
Controlling snails involves keeping the following tips in mind:
- Eliminate all hiding places where snails might take refuge during the day: under old boards, stones, debris, plastic tarps, stacked pots, weedy areas around tree trunks, dense ground covers and leafy, low-growing branches.
- Daily monitoring of hard-to-control places, hand-picking and disposal are important tasks to perform until snail numbers are significantly decreased. Then inspect weekly.
- Avoid overwatering. Irrigate early in the day so things dry out by evening.
- Place 12-sq.-in. wood pieces, elevated an inch or so off the ground, in favorite hiding places to trap and collect snails. Check under the boards daily the first week, every other day during the second week, every three to four days the third week and weekly thereafter.
- Snails are unable to cross copper, so place copper barriers (strips) around planter boxes, trunks or greenhouse bench legs.
- Use predatory decollate snails as a natural biological control.
- As for baits, remember they are toxic to decollate snails, pets and children. Using the above methods should reduce snail population enough so chemical control will not be necessary. There are several problems with using baits. In the scientific community, there is the question of whether a bait is more attractive to snails than their preferred food.
- Caffeine is known to be a great snail killer. However, the bitter taste of caffeine keeps snails from eating lethal amounts in bait preparations.
And don’t forget, there is one more method of controlling snails: eating them.