Answer: Fortnately, times have changed and safer, more convenient controls have been developed. Instead of tar, which can be problematic for trees, beneficial insects and orchardists alike, apply a thick coat of insecticidal soap to tree trunks this spring before the adult beetles become active and lay eggs - usually 2-4 weeks after petal fall. For best effect, remove vegetation from around the base of the tree before applying soap, since Flathead Appletree Borers (the most likely culprit) lay eggs on the trunk very close to the ground. If it's well past petal fall in your area already, use a broom to brush tree trunks vigorously where they meet the soil. This should dislodge the eggs, but for safety's sake, keep an eye on the trees and look for tell-tale holes and frass as the season progresses. If you find these clues, use a stiff wire to poke the borers to do them in. Hope this helps!
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