Note: I sprayed Sevin on the trunk from the base to 2 ft high on 17 March, on 19 Mar I noticed the first silk bags forming. Most of the silk bags are 12-25 ft high.
Hardiness Zone: 7a
Scott from Hollywood, MD
Eastern Tent caterpillar larvae feed on the leaves of most deciduous trees and shrubs, but especially crab apples, aspens and wild cherry trees. In the past few years, caterpillar numbers have been high in your area. Thankfully, these population explosions are cyclical, and native parasites will eventually bring numbers back under control.
One idea for getting rid of the sacks high up in your tree is to wind them onto a broomstick with nails projecting from it. This is best done in the morning when the caterpillars are inside their tents. Where you can reach, you can also prune and burn the infested branches. Another, (microbial) method of control is spraying Bacillus thuringiensis var.kurstaki, also known as (BTK).
One way to prevent future infestations is by attracting native parasitic flies and wasps. This can be done by growing small, flowering herbs like Queen Anne's lace, catnip, and wildflowers around your garden and near the base of your tree.
Here's a great link for more information specific to your area.
Good luck!
Ellen
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We had tent caterpillars on our fruit trees. If left alone they will strip all of the leaves off. I put in a small spray bottle 25% water and 75% vegetable oil.
We live in southern Ontario, Canada, and tent caterpillars are a big problem. We always had them on our few fruit trees until I read somewhere of a cheap way to discourage them.