Garden Update: Snails and Slugs

By Kathleen Cue, Nebraska Extension Horticulture Educator in Dodge County (Week of September 20, 2021)

Snails and slugs are noted for their voracious appetites, eating holes in the leaves of hosta (their preferred food) but also munching on roses, ferns, impatiens, begonias, and fruits, including strawberries and tomatoes. You may not see the actual snails and slugs themselves since they prefer to feed at night or on cloudy days, but if you see holes AND their silvery slime trails, these guys are making themselves at home. Typically, snails and slugs prefer to slime their way to the center of leaves where they will eat holes between leaf veins. Sometimes they eat their way inward from leaf edges.

Both snails and slugs are mollusks. They move about, crawling along with one muscular “foot” structure. This muscle secretes mucus to make travelling easier.  Snails and slugs have a similar appearance except snails have a shell and slugs are shell-less.

Gardeners should employ a multitude of strategies to lower snail and slug numbers.

•Surround plants with diatomaceous earth in a band about one inch high by three inches wide. Diatomaceous earth is tiny shell shards of ancient marine animals.  As slugs and snails crawl across diatomaceous earth, their bodies are punctured, causing dehydration and death. Diatomaceous earth loses its effectiveness when wet, so re-applications will have to be made after a rainstorm.

•Use drip irrigation to reduce humidity and wet surfaces. Dry areas incur less snail and slug activity than damp places do.

•Snails and slugs are attracted to the smell of fermentation. You can lay a beer trap for them by burying a shallow dish in the soil, so the top of the dish is even with the soil surface. Fill the trap with beer or near beer. Snails and slugs will crawl towards the scent, fall into the trap, and then drown. Check the trap regularly, emptying it and adding more beer as needed.

•Lay old boards around the base of plants. Snails and slugs like to congregate in cool moist places. Every morning, the boards can be flipped over, and gardeners can step on the mollusks hiding there.

•Iron phosphate, sold as Sluggo® or Escar-Go®, interferes with snail and slug metabolism, causing them to cease their feeding and later dying. These products are labeled for use on ornamentals and food crops.

•Pesticides containing the active ingredient metaldehyde are effective against these mollusks by dehydrating them but may be ineffective when rainfall or irrigation provides the necessary water to re-hydrates snails and slugs.

Photo from University of Maryland Extension.

  (Photo courtesy of University of Maryland Extension.)