That Trail of Slime Can Only Mean Slugs
Shiny, silvery trails leading away from your home and plants may, at first glance, appear mysterious and wonderful, until you realize that the visitors who left them weren’t the stuff of mythology – they were slugs! Not at all ethereal and lacking in social graces, these common pests may consume landscaping aggressively during the night, leaving their sticky mucus behind.
What Are Slugs, Anyway?
Slugs are mollusks that lack a shell – they’re closely related to garden snails, oysters, and clams. Like their snail cousins, slugs glide along the ground on a large, muscular foot using a layer of mucus they produce from their bodies. Because these garden pests lack a thick shell, they are most active at night, or on days when it’s rainy and cool; they hide in dark, moist places during the heat of the day.
When Slugs Attack
These sticky pests may invade basements looking for a safe place to hide from the heat of the day, or slugs may work their way under siding and hang around under porches. Besides leaving slime trails, slugs do no damage to structures, although their presence speaks to the potential for these areas to be invaded by more troubling pests.
During the night, slugs feed on rotting organic material or succulent plant growth when it’s available. You may wake to find that your favorite hostas have smooth-sided holes chewed throughout their foliage or that just-ripening strawberry fruits have been damaged beyond use after slugs have visited. Slugs often clip newly emerging seedlings at or near their bases, as well.
Slug Control Tips
Slugs respond to many control methods and are easiest to eliminate when you combine several different techniques. Using hand-picking or trapping, baiting, and exclusion together typically creates the most effective combination for slugs in the landscape once the favorable habitat is eliminated. In a basement, habitat modification and exclusion are often all that’s required before picking the few stragglers off the walls and scraping away eggs.
- Habitat modifications for slug control involve removing wet, humid, or dark areas where slugs hide. Cleaning up debris in the yard and removing old, decaying layers of mulch from around plants make it harder for slugs to hide from the sun. Correcting drainage problems and watering early in the day creates drier, slug-hostile landscapes. Thinning plants with thick growth close to the ground allow better airflow, reducing humidity.
- Hand-picking is time-consuming but can be effective for controlling slugs if you keep at it. Take a flashlight and bucket of soapy water to areas where you’ve noticed signs of slugs. Check within plant canopies, behind any objects, on the bottoms of pots and even under siding where slug trails are noticeable. Daily hand-picking is necessary to break the life cycle of slugs, but once they become difficult to locate on a daily basis, weekly monitoring is often adequate for prevention of future problems.
- Copper barriers work by activating the slug’s nervous system – when the slug crosses copper, they experience a sensation similar to an electric shock. Understandably, this feeling makes them back away quickly. An unbroken copper barrier surrounding troubled gardens, trees, pots or porches will prevent slugs crossing into these areas, but also leaves those slugs already in the forbidden zones marooned inside.
- Commercial traps are available for slugs, but any shallow container wide enough to hold your problem slugs will do when buried with only about 1/2 inch of the lip remaining above ground. Place traps near slug-plagued areas, then fill them halfway with beer. Slug traps are extremely effective but must be checked daily to remove bodies and be replenished with fresh beer.
- Slug baits containing metaldehyde are readily available in hardware stores but pose a significant risk to animals and children when used in accessible locations. Iron phosphate baits are less common, but are usually stocked nearby – these baits are not dangerous for mammals but are just as effective as metaldehyde for slugs when used properly. Scatter baits in slug-prone areas, as well as inside areas surrounded by barriers. Slug baits must be replaced every few days and anytime it rains for best effect.
Slug control can be time-consuming – if your schedule doesn’t allow for frequent slug monitoring, you should consider calling a pest control expert. These professionals will consider the nature of your slug problem and provide an answer that best suits your needs.