Could cedar mulch stop red lily leaf beetle?

red lily leaf beetles mating
The red lily leaf beetle is spreading in Western New York, causing damage to lilies and fritillaria. Photo courtesy Gordon Ballard

by Connie Oswald Stofko

Is it possible that there could be an easy way to keep the red lily leaf beetle from damaging lilies?

A local gardener may have stumbled across a way: cedar mulch.

John Farfaglia, extension educator with Cornell Cooperative Extension in Niagara County, was contacted by the gardener. She had happened to put cedar mulch in the bed where she has lilies and discovered that the pests didn’t bother her lilies.

“It might just be a coincidence” that the red lily leaf beetles didn’t attack lilies in the bed with the cedar mulch, Farfaglia said, “but there might be something to it.”

Natural oils found in cedar give off a scent that can repel certain insects, he explained. Adult red lily leaf beetles overwinter in the soil, so the cedar mulch on top of the soil might be interrupting their normal behaviors.

Maybe the beetles don’t want to overwinter where there is cedar mulch, so they move to another area, Farfaglia said. Or perhaps when they exit in the spring and find themselves in cedar mulch, they move to another area.

If you want to try this, Farfaglia suggests putting two or three inches of cedar mulch around your lilies now. If you don’t do it now, do it by early spring because the beetles emerge in early spring.

Farfaglia wants to know your results, good or bad, in the spring. Does cedar mulch seem to keep red lily leaf beetles from damaging your lilies or not? Email him at jaf21@cornell.edu or call 433-8839, ext. 226.

Gardeners would be ecstatic if it turned out that there was such a simple solution to the problem of red lily leaf beetles. Some gardeners have completely given up growing lilies because of the damage done by these pests.

Find out more about dealing with the red lily leaf beetle in these previous articles.

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