This one was surprisingly straightforward to identify. The lack of a sclerite at the base of the lateral hump narrows the field quite a bit, and the other options followed fairly obvious characteristics to Clostoeca, which only has one species, Clostoeca disjuncta.
Tuckcast on Jul 14, 2019July 14th, 2019, 7:22 am EDT
I took these from the mouth of a trout I caught in Oil Creek in
NW PA. I occasionally find these in the mouths of fish in this stream. These bugs were out of water for about 8 hrs when I remembered about them. As soon
as I put them in water 2 of them just took off swimming. The 3rd one had expired. What I’d like to know is: Are these fish food or parasites of some sort? The large one is about a size 18 nymph hook.