During last season, my hosta leaves were really chewed up. Is this due to mites or slugs? Any recommendations on preventing it?
Mites are not what chewed your hosta leaves. It’s those slimy critters that are part of the mollusk family: slugs. They, as well as garden snails, use tooth-like jaws to saw through leaves and flowers. Like bats, these garden pests feed at night and on overcast or rainy days. They are most active during warm, rainy springs. While there are more than 25 slug species in the United States, hostas’ real enemies are the little black and brown slugs that eat both shoots and roots.
Slugs slide along on a slime trail that’s excreted by their single large foot. Their eyes are located at the end of the large tentacles on their head, while the smaller tentacles enable them to smell. Slugs are hermaphroditic, containing both female and male organs. Nonetheless, they need to pair in order to breed, usually in the spring or fall when weather is mild and moist. In fact, slugs are more prolific than rabbits, laying clusters of 40 to 100 gelatinous eggs in the soil, under rocks, and in outdoor pots. After hatching, slugs can mature in a few months; as adults, they can mate up to six times a year.
- While ridding your garden of slugs is not easy, there are many simple things you can do in the garden to decrease their damage:
- Eliminate their habitat. Garden debris provides a hiding place. Using less mulch will reduce your slug population.
- Hand pick slugs during the evening and early morning hours. Crush them or dispose of them in a bucket of soapy water.
- Add plants such as ginger, garlic, mint, chives, red lettuce, red cabbage, sage, sunflower, fennel, foxglove, astilbe, ferns, mint, chicory, and endive that have foliage and toxins less desirable to slugs. Also consider planting some of the blue type or waffled-leaved hostas that slugs seem to scorn.
- Create a barrier of abrasive material such as crushed eggshells, sand, wood shavings, diatomaceous earth, hair or ash around your hostas. Keep these materials dry and replenish them after it rains. Take care using diatomaceous earth as it may damage your lungs if breathed; use a face mask when applying it.
- Drowning slugs in beer is not as effective as you may think. Dissolving yeast in water can be just as effective and much less expensive. If you choose this option, bury several containers at ground level, empty them and refill them daily. However, you may have too many slugs for this method to be effective.
- Much of the slug’s body is water so they are susceptible to drying out. Cultivate your soil in early spring to expose their eggs to drying air & predators. Try to keep your garden as dry as possible without damaging your plants.
- Iron phosphate baits decrease slug populations without harming birds, small pets or humans. These baits are sold under the name Sluggo, Es-car-go, and Safer’s Slug & Snail Bait.
- Set up a barrier with copper strips or tape. Slugs will not cross the copper. When they slide over it, there is a toxic reaction, similar to an electric shock.
- Attract predators that eat slugs such as ground beetles, frogs, birds, and ducks.
- Lastly, try coffee grounds. Researchers have found that slugs have a real distaste for caffeine. The grounds themselves repel slugs, but a 1 to 2 percent caffeine solution kills nearly all slugs within two days.