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We have a horrible locust infestation, which I can't find any news about - all of the scrub oak are defoliated. Is this common? Will the trees recover- new leaves this year? I have found them on fruit trees and washed them off - are they just passing through? Any other info on them?

Answer(s)

A

The insect infesting Gamble oak and other trees in northern Utah is the cankerworm.  The caterpillars can defoliate the trees when they occur in high numbers such as this year.  Most healthy, nonstressed trees will produce a new crop of leaves when the caterpillars have completed their development.  For trees in your yard you can spray them with a bacterial insecticide that is specific for caterpillars and nontoxic to mammals.
Products available include those with the active ingedient Bacillus thuringiensis (Dipel, Thuricide, others) and spinosad (Success, Entrust, Conserve).  Thorough cov erage of leaves is important because the caterpillars must ingest the insecticide for activity.

Posted on 5 Sep 2007

Diane Alston
Hort-Entomologist Specialist

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