New insect pest puts the brakes on lily order


My neighbor spent time this summer talking me into trying Orienpet lilies. He has a magnificent stand of them and insists deer have no interest in them. That’s remarkable since deer are notorious for their love of lily buds.

Orienpets, also known as tree lilies, can be 8 feet in height and loaded with flowers up to 8 inches in diameter. That’s a lot of snacking for deer to pass up.

I was sold on the lilies and spent several happy nights perusing bulb catalogs. I grow both Asiatic and Oriental lilies but have never tried Orienpets. They’re a cross between trumpet lilies and the Oriental types. Many are hardy into zone 3 and 4 and they retain the fragrance Oriental lilies like ‘Casablanca’ are famed for.

I happily filled out an order form for a couple of beautiful Orienpets. But before I could send it, I was distracted by my husband, who mentioned he’d seen an article about a new insect pest in Wisconsin. Since we’re going to have to treat our viburnums for beetles this winter and emerald ash borers are still eating up local ash trees, I figured I’d better check the new threat out.

I went straight to the website of the University of Wisconsin – Madison Insect Diagnostic Lab. It’s a great resource for Wisconsin gardeners. Yes, in addition to Japanese beetles, jumping worms and viburnum beetles, there’s a new Eurasian pest for Wisconsin gardeners to look out for — scarlet lily beetles (Lilioceris lilii).

Just as with viburnum beetles, these new pests can cause heavy damage to members of the lily family. The adults are about a quarter-inch long with bright red backs, narrow thoraxes and wide abdomens. They feed on lily leaves, stems and buds. The adult beetles overwinter in the soil, so they appear early in the season, laying tiny reddish-orange eggs on the midrib on the underside of lily leaves. When threatened, the adults fall to the ground and lay on their backs since their dark undersides are hard to spot. They may also click to give themselves time to scuttle away from startled predators.

The beetle larvae are pale yellow, about a half-inch long with a black head. The larvae disguise themselves by gluing their own excrement to their bodies so they look like a gooey splotch of poop. It only takes about six weeks to produce a new generation of beetles, so they’re active all summer. The beetles may also feed on fritillaries, lily-of-the-valley and Soloman’s seal.

So far there are no reports of scarlet lily beetles in Ozaukee County, but they’ve been in the state since 2014. They spread naturally, but the jump in reports in non-contiguous counties suggests they’re being spread by humans.

There are no safe treatments for the insects, although Neem can be used to destroy eggs and very young larvae. Other effective treatments are also toxic to bees and other beneficial insects.

I didn’t order the lilies. With close to three dozen viburnums to treat for beetle infestation, I’m not in the mood to deal with more problem plants. I’ll just have to enjoy the lilies I have and hope these new pests remain at bay. But I’ll look for them in the spring. Maybe being forewarned will actually be helpful in limiting potential damage.



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Ozaukee Press

Wisconsin’s largest paid circulation community weekly newspaper. Serving Port Washington, Saukville, Grafton, Fredonia, Belgium, as well as Ozaukee County government. Locally owned and printed in Port Washington, Wisconsin.

125 E. Main St.
Port Washington, WI 53074
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