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Slugs in home gardens

Quick facts

  • Slugs are present from spring to fall, in cool, moist areas with shade.
  • Slugs feed on leaves of many plants (especially seedlings), ripening fruits and vegetables, and decaying plant matter.
  • Extensive feeding can result in a weak or dying plant.
  • There are several nonchemical steps to combat slugs.
  • Insecticidal baits are also available if necessary.
A slimy brownish slug on a green leaf

How to identify slugs

Slugs can be described as snails without shells. They are a type of mollusk, related to clams and oysters.

  • Slugs are slimy and soft bodied, without any legs.
  • They are generally brownish or grayish.
  • Their head contains two pairs of feelers. A larger pair above carries the eyes and a lower pair below is used for smelling.
  • They can range in size from 1/4 inch to two inches or longer.

Slugs produce slime and use it to move. A dried slime trail indicates slugs are active in your garden.

Biology of slugs

Slugs are generally active at night when it is cool and damp, although they may be seen during the day in cool, shaded sites. Warm, dry conditions are less favorable to them.

  • Slugs typically spend the winter as eggs in protected sites, like under plant debris, mulch, boards or in the soil.
  • Eggs hatch the following spring and early summer.
  • If conditions are favorable, slugs can be active throughout the summer and fall.
  • Slugs have a layer of slime to protect their skin from drying up.

Slugs feed on a variety of ornamental plants that grow in part to full shade as well as fruits and vegetables. Some plants they are likely to damage include bellflower (Campanula), larkspur (Delphinium), plantain lily (Hosta), daylily (Hemerocallis), Dahlia, lungwort (Pulmonaria), strawberries, basil, beans, cabbage and lettuce. 

Ground covers like spotted dead nettle (Lamium maculatum) create an inviting slug habitat by shading soil and keeping it cool and moist.

Generally, slugs do not bother plants that grow in full sun.

Damage caused by slugs

  • Slugs use file-like mouthparts (called a radula) to rasp and chew plant tissue.
  • Because of their mouthparts, they create irregularly shaped holes in leaves, flowers and fruit.
  • Low to moderate feeding can affect the appearance of plants but usually does not impact plant health.
  • Severe slug feeding can injure plants, especially seedlings.
  • It can also reduce the harvest of fruits and vegetables, especially when plants are young. Older plants are more tolerant of defoliation.
Slug on a hosta leaf with irregular holes
Slug feeding on hosta
Brownish slug making holes on a tomato
Slug damaging tomato
Hole created on a strawberry due to slug feeding
Slug damage on strawberry

How to protect your garden from slugs

If slugs are a problem in your home garden, it is best to use a variety of steps to reduce their numbers. Wet conditions caused by excessive shade or poorly drained soil can increase slug numbers.

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Authors: Julie Weisenhorn, Extension horticulture educator and Jeff Hahn, Extension entomologist

Reviewed in 2020

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