I went on a family vacation to Idaho this summer. My family and I went on a hike together. As we were walking on the trail, we moved the tree branches out of our path. We discovered the larva cocoon.
This photo was taken on a hiking trail in Paris, Idaho.
I would be glad to find this in the wilderness, less excited to find it in my own yard. When I was a kid, I'd see these every summer but I haven't seen one in years. Thanks for sharing.
They look like tent caterpillars. We had them on our fruit trees. I mixed a tablespoon of vegetable oil with a cup of water in a spray bottle.
Yeah, that "larva cocoon" is a nest of tent caterpillars that will eat every leaf on the tree or shrub, then move on to other trees. In large enough numbers, these tent caterpillars can defoliate huge swaths of forest in a single season. The best thing to do, is to eliminate them while still in this web nest. I have found the easiest way is to hold my lit propane torch under the nest and let them burn. If any drop off untouched, those get stomped into the ground. Birds won't eat them, but if you have a fish pond or are on a lake, the fish LOVE them! But really, any nest you find should be eliminated if at all possible.