On 7 May 2016, I retrieved a large caterpillar from a valley oak tree. I attempted to raise it, but the caterpillar died in the cocoon stage. Dr. Lynn Kimsey (thanks!) identified it as a Pacific tent caterpillar, Malacosoma constricta. It was a solo individual, and no netting or tenting was seen. Below are photos of the frass and the caterpillar. For image of moth, see this page.
Distribution of the Pacific Tent Caterpillar
Collected by David Katosic, 16 March 2017. Apple Valley Estates, coming from behind exterior window trim.
Then, on 17 April 2017, David Katosic retrieved samples from within the window casing, and it was quite interesting. See below, IN THE NEST.
IN THE NEST
The nest was accessed. It appears we have solitary bee nest. The interior of the nest itself had a mixture of pollen, larval frass, minerals used to construct the nest, and mites. We videoed the mites, and the link is at the bottom of this post.