Averting our caterpillar crisis
Help! We have a giant oak tree about 10 feet away from our 168 year old house. A few years ago a forester told us he believed it to be 400 years old! However last spring/summer we had an infestation of caterpillars that consumed most of the foliage. I did not collect any of the caterpillars, but I did collect the adults. I’m not sure that the leaf in the picture was part of the problem...is there a predatory insect that we can use to kill the caterpillars? The photos of the house include the tree in the background in 2017. Thanks!
The moths in your picture look like adults of the Gypsy Moth (Lymantria dispar). The good news is that there is a natural disease that keeps them in check most years as long as we get sufficient rainfall. Also, otherwise healthy trees can tolerate sever defoliation for a single season or even two without detriment. To protect this tree you can try a tactic known as "banding". This involves using tree wrap and a special sticky substance to keep the caterpillars off of the tree. Your local district forester or extension office may be able to help you locate a local source for these materials. You should also look for and destroy any Gypsy Moth egg masses. For a picture of a gypsy moth egg mass, see this MSU Extension article from last spring: https://www.canr.msu.edu/news/growing_populations_of_gypsy_moth_caterpillars_raise_concern_for_landscapes