This is a striking caddis larva with an interesting color pattern on the head. Here are some characteristics I was able to see under the microscope, but could not easily expose for a picture:
- The
prosternal horn is present.
- The
mandible is clearly toothed, not formed into a uniform scraper blade.
- The seems to be only 2 major
setae on the
ventral edge of the hind
femur.
-
Chloride epithelia seem to be absent from the
dorsal side of any
abdominal segments.
Based on these characteristics and the ones more easily visible from the pictures, this seems to be
Grammotaulius. The key's description of the case is spot-on: "Case cylindrical, made of
longitudinally arranged sedge or similar leaves," as is the description of the markings on the head, "
Dorsum of head light brownish yellow with numerous discrete, small, dark spots." The spot pattern on the head is a very good match to figure 19.312 of
Merritt R.W., Cummins, K.W., and Berg, M.B. (2019). The species ID is based on
Grammotaulius betteni being the only species of this genus known in Washington state.