Slow as they may seem, a "rout" of snails can quickly consume your garden. Especially in wet weather, these slimy visitors seem to appear out of nowhere, and they're hungry.
But did you know that some snail species are beneficial? In Florida, only a few species of snails and slugs actually damage living plants. Others live on fungi or decaying plant material, or are predatory and feed on other snails. These predatory snails are beneficial, helping us keep the true pests in check.
If your garden is plagued by snails, you know that they behave differently than other garden pests. This is because snails and slugs are mollusks, not insects. They are relatives of conch, oysters, clams, and scallops.
Most snails are omnivores, feeding on fungi, decomposing plants, and soil. Some feed on healthy plants, however, and these are the species that make pests of themselves in your garden. It's unusual to catch them eating though; snails feed primarily at night.
Damage from snails appears as oblong, irregular holes at both the margin and the center of leaves and flowers. Thicker leaves may have damage on only one side. Oftentimes you'll see trails of mucous around these damaged sites.
Being nocturnal, these pests aren't always feeding when you're scouting. Snails don't usually go far though — if they are indeed the culprits you'll find them under pots, mulch, and leaf litter nearby.
For the most part, snails prefer natural, undisturbed areas. Only a few species are likely to be garden pests. And there are garden-friendly snails, too. Predatory snails, like the rosy wolf snail (Euglandina rosea), feed on other snails and slugs.
To avoid killing the snails that help manage other garden pests, we encourage all gardeners to identify snails before attempting any control methods. Snap a picture and email it to if-svc-marionmg@ad.ufl.edu We'll be happy to help you ID the mollusk in question.
Another reason to have your snails identified is to help scientists track and eliminate invasive species. Snails reproduce by laying eggs but most adults are hermaphroditic. This means they are both male and female, making invasive species more difficult to eradicate. Even if you take no other action, sending in a photo to be identified can be very helpful to the work of Florida's scientists and Extension agents.
Pest Management
Integrated pest management, or IPM, is a comprehensive approach to managing plant pests. IPM uses many different methods to cause the least harm to people, property, and the environment. While there are chemicals available to manage snail populations, we suggest beginning with cultural and mechanical management.
Cultural Practices — Snails require very moist environments. Reducing irrigation can make your garden less appealing. Removing excess leaf litter, mulch, wood, and stones from the base of your plants will also help. If these habitats can't be removed, you can scout regularly and keep populations down mechanically. Encouraging biological control, by welcoming the predators that eat garden snails, is another cultural option. Identify your snails before you reach for a chemical control to avoid eliminating beneficial species.
Mechanical Practices — Snails can be trapped and removed easily. If you provide a shady, moist environment (like a piece of cardboard laid on the ground) they will hide underneath as the day warms up. Later in the day you can lift the cardboard and remove or kill them by hand. Another popular trap involves sinking a steep-sided vessel, like a cup, into the soil to about ground level. Fill the cup with beer or another bait. Snails will enter and remain trapped.
Diatomaceous earth and egg shells are reported to kill snails, too, but we have no research to support this claim. The logic is that these abrasive materials damage the pests' soft undersides as they cross them. Another common barrier is copper, but in Florida it oxidizes quickly and becomes inactive.
Chemical Controls — Most people know salt is toxic to snails. Unfortunately, salting your garden will damage your plants. Apply enough salt and you can ruin your soil, too. Hydrated lime and sulfur dust can also deter snails but, again, they will also change the composition of your soil.
The pesticides that control snails are called "molluscicides." These are commonly baits, which are a combination of a food to attract the snails that is mixed with a chemical substance that is lethal to them. Any molluscicide must be registered with the Environmental Protection Agency (EPA) and will contain a label with explicit instructions for use. Remember: the label is the law. To be used effectively and without unreasonable risk of harm to people or the environment these products must always be used according to the label.
|