Insects on red twigged dogwoods
Last Summer my red twigged dogwoods were infested with a small white caterpillar that completely defoliaged the bushes in a matter of weeks. Should I spray the bushes early this season to avoid the problem? and do you have an idea on the identity of this insect? Thank you.
Baltimore County Maryland
We are glad you asked!
Chances are, what you have are dogwood sawfly larvae, which are not actually caterpillars, and the pesticides that people use to control caterpillars do not work on them.
Dogwood sawfly larvae are white and are gregarious, which in this case means they often feed together in groups.
Populations can vary from year to year, but even with defoliation, it is usually early enough in the season that the plant just grows new leaves. They are seldom a problem. (and they are food for other wildlife like birds)
If you want to control them, you can hand pick them by brushing them into a bucket of soapy water to drown. If populations are high you could also spray them with an insecticidal oil, which works best while they are small.