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Slugs and Snails

Garden pest

Description​

Slugs and snails are soft-bodied mollusks that feed on many garden plants. Snails carry a visible shell; most slugs have no external shell. Both move on a muscular foot and leave mucus trails that may dry to a silvery sheen. They are most active at night and during damp, mild weather, hiding by day beneath pots, boards, dense foliage, mulch, or debris. They scrape plant tissue with a rasping mouthpart, often making irregular holes in leaves or eating the edges. Tender seedlings can be eaten almost completely, while flowers and fruit touching the ground may also be damaged. Feeding tends to increase after rain or frequent evening watering. Damage varies by species and plant: some feed mainly above ground, while others live in soil and attack roots or tubers. A few mollusks in a garden do not necessarily require control; focus on protecting vulnerable young plants.

Symptoms​

  • Holes in leaves
  • Slime trails
  • Stems chewed or cut through

How to Identify​

Look for ragged, irregular holes, often starting at leaf edges, and silvery slime trails on leaves, soil, pots, or paving. Inspect plants with a flashlight after dark or early in the morning, especially following rain; check beneath pots, boards, and low leaves. Snails are recognizable by their shells, while slugs lack a conspicuous shell. Caterpillars and beetles can also chew holes, but they do not leave slime trails; look instead for the insects or their droppings. Damage confined to seedlings at soil level may also be caused by cutworms. Slime trails and a nighttime sighting provide stronger evidence than holes alone.

Prevention​

Water in the morning so the soil surface has time to dry before night. Avoid overwatering, improve drainage where needed, and remove weeds, plant debris, and unnecessary objects that provide moist daytime shelter. Space plants to improve airflow, while retaining mulch where it benefits the crop; keep thick, persistently wet mulch away from vulnerable seedlings. Check new plants and containers for hidden slugs, snails, or eggs before putting them in the garden. Protect young transplants with collars or other barriers that have no gaps. Copper tape around pots or raised beds may deter mollusks if it forms a continuous, clean band with no overhanging leaves that provide a bridge. Inspect susceptible crops regularly, particularly in damp weather, so damage is caught early.

Treatment​

Start by hand-picking slugs and snails after dark or at dawn, using a flashlight; check their hiding places and repeat over several nights. Drop collected mollusks into soapy water. You can lay a board on damp soil as a shelter trap, then lift it each morning and remove any mollusks beneath it. Protect individual seedlings with well-fitted collars or barriers, and move fruit off the soil where practical. If damage continues, use an iron-phosphate slug-and-snail bait labeled for your site and crop. Scatter it thinly according to the label rather than piling it near plants, and store it away from children and pets. Some regions offer slug-control nematodes for use in moist soil; follow the product directions and note that they may not control snails. Avoid spreading salt on garden soil, which can harm plants. Metaldehyde baits pose greater risks to pets and wildlife and are best avoided.

Plants Affected​

Artichoke, Asparagus, Basil, Black-eyed Susan, Bluebell, Bok Choy, Borage, Brussels Sprouts, Burdock Root, Cabbage, Cauliflower, Celeriac, Celery, Chervil, Clematis, Crocus, Daffodil, Daisy, Dandelion Greens, Delphinium, Endive, Fava Bean, Fennel, Forget-me-not, Hosta, Hyacinth, Jerusalem Artichoke, Kale, Lettuce, Lily, Lovage, Lupine, Marigold, Nasturtium, Pansy, Poppy, Purslane, Radicchio, Red Cabbage, Romanesco, Salsify, Savoy Cabbage, Scarlet Runner Bean, Scorzonera, Snap Pea, Snow Pea, Snowdrop, Sorrel, Strawberry, Sunchoke, Sweet Pea, Swiss Chard, Tulip, Watercress

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