Except for a few that migrate, all of the insects of spring, summer, and fall are still here in Pennsylvania over the winter. On a nature walk, you are more likely to see the evidence of insects, such as their feeding places and built shelters, than the insects themselves. Most are buried in the ground, mud, or leaf litter. Searching for this evidence is like a treasure hunt each winter.
Look among the bare branches of trees and shrubs for any bit of material attached to them, perhaps a leaf or something unrecognizable. Among the things you may find are several types of cocoons. The larger ones will be those of silk moths, smaller ones wrapped inside a leaf will likely belong to tussock moths. Tiny groups of cocoons, each no more than a quarter inch long probably belong to braconid wasps. Another cocoon like structure hanging off of twigs will be the larva cases of bagworm moths. They are about half of an inch to 2 inches long.
If you find a tiny bit of curled up leaf attached to a willow or poplar, you may have found the winter home of a viceroy butterfly. And if you find little holes lined along a twig, you may have discovered the eggs of tree crickets. Another treasure on twigs is the egg case of a mantis, a 1 inch sphere made of layers of hardened tan foam.
If you go into the woods, look for dead or dying trees and check under their bark for the tunnel patterns of bark beetles. Beneath the trees and on the surface of the snow, look for one of the few active winter insects, the snow flea. This insect is so small that groups of them look like pepper sprinkled in the snow.
All the photos in this post are just a few overwintering insects found at Tree Pittsburgh’s campus, waiting for spring to awaken them.