Answer: At this time of year, it's probably tent caterpillars. They generally expand their tent-like home as they feed so you'll probably see the mass continue to grow for several weeks. Chemical control is difficult because they're protected by their webbing. For the most part, their damage isn't too serious and healthy trees will recover when the caterpillars leave. When tent caterpillar populations grow large enough, beneficial wasps arrive to take care of them. The wasps lay eggs inside the caterpillars. When the eggs hatch, hungry larvae feed on the insides of the caterpillars.
Q&A Library Searching Tips