You just planted a tidy row of tiny broccoli in your garden. But when you head outside the next morning, you discover the foliage is full of weirdly-shaped holes—and some of the seedlings are gone!
Chances are, it’s the work of slugs. “Slugs are soft-bodied animals that live in moist areas and feed on many different types of edible and ornamental plants,” says Rafia Khan, PhD, assistant professor and extension entomologist at Texas A&M AgriLife Research and Extension Center. “Because they are nocturnal, you’ll often notice damage before you identify what’s causing it.”
During the day, you likely will not see slugs. “They are hiding under mulch, leaf litter, and pots on the patio,” says Wendy Wilber, statewide master gardener volunteer coordinator for the University of Florida Institute of Food and Agricultural Sciences. “They become active again when temperatures are cool, after a rain shower, or on a cloudy day.”
Interestingly, slugs have both male and female reproductive organs, so they all can lay eggs. These eggs are deposited in clusters on the soil or in protected locations, such as under leaves. Because slugs can lay eggs multiple times per year, you can have slug problems for the entire growing season. The eggs also can overwinter and hatch in spring, says Khan.
Slugs do have a valuable role in cleaning up decaying plant matter. They’re also are a vital part of the food chain for creatures such as birds, moles, toads, carnivorous ground beetles and firefly beetles. But because they can consume several times their body weight each night, they can cause lots of damage in a short time in your garden, says Wilber.
How To Get Rid Of Slugs
There’s no foolproof way to get rid of slugs, but you can try a combination of these techniques to manage their populations, according to Khan and Wilber:
Monitor your plants. Look for clues that slugs are the culprits, such as overnight foliage damage and slimy trails, says Khan.
Scout for slugs in the early morning, at dusk, and on rainy days. Inspect areas where they shelter, such as under nearby benches, leaf litter, thick foliage, and beneath potted plants, says Khan. Use gloves to handpick them, then toss in bucket of soapy water.
Remove hiding places. Use pot feet to keep planters elevated so there’s nowhere for them to hide, says Wilber. Thin heavy mulch, and remove rotting wood, debris piles and rocks where they can retreat from the heat.
Water early in the day so plants and soil can dry out and not provide refuge. Also, consider using drip instead of overhead irrigation, says Khan.
Grow plants they don’t love. That includes those that are highly-scented such as rosemary, geraniums, sage, and lavender, says Khan.
In fall, clean up vegetation from areas where you’ve had problems during the season, such as near your hostas or daylilies, says Wilber. This may reduce overwintering eggs.
Use cardboard traps. Place a piece of 6 x 6-inch piece of cardboard or thin plywood on the garden surface to attract slugs, then check under it every morning. Use gloves to gather them, then toss into soapy water.
Make DIY traps to drown them. Bury a quart-sized yogurt container so that the lip is flush with the soil surface. It’s not necessary to use beer, which is often recommended; instead, fill the container with water and a sprinkle of yeast and sugar to attract them. Clean the trap and refill every day or two, says Wilber.
Try barrier methods to protect plants, especially seedlings. Diatomaceous earth, which has an abrasive quality that scratches these soft-bodied creatures, can be sprinkled around plants; but it must be reapplied after rain or watering. Copper foil tape, which inhibits their movements by reacting with their mucous and giving an electric shock, can be wrapped around garden bed frames, says Khan.
Consider using a commercial bait containing iron phosphate. This product interferes with the slug’s metabolism, lasts for about two weeks and doesn’t have to be reapplied after rain. Use according to label instructions, says Wilber. Other commercial baits labeled for slugs contain metaldehyde and are not the best option for your garden because they are not recommended for edibles, must be reapplied after rain, and are toxic to pets and wildlife.
Use these same methods for controlling snails. These techniques also are helpful in managing snails in your garden.
How To Identify Slug Damage
Slugs, which range from ¼ to a few inches long, have soft, squishy, legless bodies and two pairs of tentacles on their heads. They’ll eat almost any garden or ornamental plant such as cabbage, lettuce, strawberries, basil, hostas, and many annual and perennial flowers, says Khan.
Snails, which are related to slugs, cause similar damage in the garden, but they have external shells. They like the same kinds of plants but are especially attracted to calcium-rich foods such as broccoli, kale, spinach, peas and okra, which helps form their shells, says Khan.
Look for these signs of slug activity in your garden:
Plant damage that occurs overnight or whenever it is cool and wet, especially in the spring and fall or during periods of mild, wet weather, says Khan.
A slimy trail left behind on foliage or garden surfaces. “These animals move by muscular contractions, secreting mucus to allow them to glide across surfaces or move up the sides of containers. The dried-up whitish, shiny trail on leaves or other surfaces indicates their presence in the garden,” says Khan.
Large, irregular holes with smooth edges in foliage, typically located between the veins of leaves, says Wilber. Young slugs may feed on only the surface of vegetation, not all the way through the leaves. Slugs also may leave behind blackish fecal droppings.
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