Problem: Lily Leaf Beetle
Lilioceris lilii This beetle is a recent introduction to the United States, having first appeared in Boston in 1992. It has now spread throughout the Northeast, and may eventually spread to much of the country. It favors true lilies (Lilium), but sometimes feeds on fritillary, solomon''s seal, or lily-of-the-valley. It does not attack daylilies. The bright red adults spend the winter in the soil or plant debris, emerging in April. They begin to feed on lilies as soon as they appear in the spring. Females lay eggs in rows on the undersides of lily leaves. The larvae emerge in late April or May and feed for 3 or 4 weeks. The slug-like larvae carry their excrement on their backs, making them repulsive to predators, including gardeners. They pupate in the soil in June to reemerge as adults in early summer, then feed until October. The heaviest damage is done by the larvae. Researchers are searching for predators and parasites to release in this country. If they are successful, this beetle may be reduced to a minor pest.
A few adults can be handpicked. Drop them into soapy water to kill them. Most people are unwilling to pick the larvae off with bare-hands, so wear gloves. To avoid bringing more beetles into your garden, inspect new lily plants carefully for insects or eggs.