Slugs & Snails
Slugs and snails (also known as gastropods) belong to the animal group called mollusks. They feed on a variety of living plants, as well as decaying organic material. Slugs and snails are often considered a nuisance around the home and garden because they can cause extensive damage to a wide range of crops and ornamental plants – especially during mild, wet years.
Slugs and snails are similar in form, except slugs do not have a snail’s protective spiral shell. They have soft, slimy, legless bodies with rasping mouthparts and two pairs of tentacles on the head. The upper, longer pair are optic tentacles with eyes located on the end. The lower, shorter tentacles are sensory organs used for feeling and tasting. These mollusks move using a muscular “foot” that encompasses the entire bottom of its body. The foot secretes a sticky mucus, which allows them to crawl upside down or on vertical surfaces. When the mucus dries it can leave a silvery, slimy trail that shows their path. Slugs and snails range in color from whitish-yellow to shades of brown, gray or black. They can grow to lengths of .5 inch and up to several inches.
Slugs and snails often feed on young, succulent plant tissue. They scrape ragged, irregular holes in leaves and flowers, which can clip developing shoots. These pests can also damage fruits which ripen close to the ground, such as strawberries and tomatoes, by scraping small, shallow pits on their surface. However, most of the damage caused by slugs and snails occurs when they kill plants by feeding directly on seeds, or on seedlings that have germinated and emerged from the soil.
Slug & Snail – Control Measures
Slugs and snails prefer cool, moist conditions in undisturbed locations; limiting these habitats can be an important first step to prevent damage. Eliminate all possible places in which these pests can hide during the day which include areas under debris, dense weeds or leafy branches close to the ground. Allow the soil to become as warm and dry as possible by thinning heavy mulch and watering plants in the morning. This gives the soil time to dry by evening. Slugs and snails also feed on decaying plant material, and it’s important not to place weed remains or fresh grass clippings in the garden or around trees. Tilling the soil between planting-rows and in garden beds may also help to disrupt slug and snail habitat.
Thoroughly removing slugs and snails on a regular basis can be an effective eradication method. Look for these pests in the early morning as they return to their daytime hiding spots, or during the night with a flashlight. They can also be lured and captured from underneath artificial shelters consisting of boards, wet cardboard, or other similar materials placed in the garden or landscape. Melon peels are also effective for attracting slugs and snails for manual removal. Captured slugs and snails can be placed in a plastic bag and disposed of in the trash, or discarded in a bucket of soapy water and placed in a compost pile once they are deceased.
Several types of barriers can be used to repel slugs and snails from planting beds. Copper foil wrapped around garden bed frames, planting boxes and trees is effective. Barriers of diatomaceous earth, dry ash or other abrasive materials mounded in a band around garden beds can also work well if they remain dry.
Beer or yeast traps, placed at ground level, are also recommended to capture slugs and snails. These traps are not particularly effective for the time and labor involved. The bait in these traps must be replaced every few days, and slugs and snails must be within a few feet of a trap to be attracted to it.
Various types of molluscicides (i.e., pesticide used to control mollusks) formulated as a bait, are available to the public for slug and snail control. Products containing the active ingredient iron phosphate are made from naturally occurring elements and are fairly safe for use around people, pets, and other non-target organisms. Baits containing metaldehyde are also common, but are more toxic and attractive to pets and wildlife. For best results, baits should be applied after a rain or after the garden is watered, which promotes slug and snail activity. All bait products should be applied as directed by the product’s label. For more information, please contact your county West Virginia University Extension Office.
Slug & Snail – Life History
Terrestrial slugs and snails are hermaphrodites (i.e., having both male and female reproductive organs); they are all capable of laying eggs. Adults lay clusters of spherical, gelatinous eggs in the soil or other protected areas. Upon hatching, the young feed for several months before becoming sexually mature. Most slugs and snails that hatch in the spring can begin laying eggs in the fall. However, some snails may require two years to become mature. In general, slugs and snails are most active and damaging in the springtime, from April to June, and again in the fall during the months of September and October. They prefer moist soils with high mulch content, and are primarily active at night or during damp cloudy days.
Author: Daniel Frank, WVU Extension Service Entomology Specialist
Last Reviewed: May 23, 2017