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Invaders

Published in the six Nashoba Publishing papers on Friday, 3 August 2001

The Lily Leaf Beetle (Lilioceris lilii) arrived in Townsend in April. It was hard not to notice them, they’re such a pretty bright red! About the size of a ladybug, but they’re oval, not round, and don’t have spots. This pest has been spreading inexorably from Cambridge (where it was probably imported) since 1992.

In May they began laying tiny orange eggs on the underside of leaves. In early June, the larvae gobbled up leaves. The tiny, slug-like things looked diseased; I breathed a sigh of relief and didn’t worry about their appetites, because they were obviously in the process of being decimated by the balance of nature. I was wrong. These larvae excrete their feces through their skins, and retain them there, too — perhaps a defense mechanism, making them less tasty to birds.

After about three weeks the larvae drop to the ground to pupate, and in another three weeks new adults emerge, which keep eating til frost. When they strip the leaves completely, they start on the flower buds — which haven’t opened because the plant is in shock from the loss of photosynthesis.

According to the University of Rhode Island, Lilioceris sometimes also eat Soloman’s Seal, Bittersweet , Potato, Hollyhock, and Hostas. They do not eat daylilies. And they only lay their eggs on true lilies (Lilium ) — the kind with the leaves growing off a central stem, up its length — and on Fritillaries. The voracious larvae eat what they hatch onto.

These beetles, originally from Asia, have been in Europe long enough to have natural enemies there — but not here. U. Rhode Island’s Biological Control Laboratory is hoping to establish some parasitic wasps that attack it there. Tiny, almost microscopic, these predators don’t bother humans, and go specifically for Lilioceris.

If you have only a few lilies, you can try hand-picking them. When your hand approaches, they will jump off the leaf and drop to the ground, flipping over onto their backs to use their black bellies as camouflage. Hold your other hand under the leaf, or cover the ground with something light-colored to gather them up in. (Also remove eggs.)

With all my lilies, this is too much for me. I can’t use pesticides; if you do, be careful not to get them on flowers, to avoid killing pollinating insects needed by food crops. The organic pesticide Neem will kill them; it must be applied every 5-7 days after egg hatch.

I think I’m going to end up planting a lot more daylilies.

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© Copyright 2001 Catherine Holmes Clark