Subject: Seattle Mystery Bug
Location: Seattle WA
February 1, 2013 7:55 am
I was wondering if you could tell me what this brown flying insect is, as seen in a Pacific Northwest living room on 01/31/2013. I’ve never seen one of these before, and now this is the second one I’ve found inside a house in two days. It may be very common, but is new to me. It’s brown and about 1 1/2” long. The pattern on the wings makes it look like it is made of wood. I thought it was a moth when it first flew by, but it is sort of slow moving, a clumsy flier, and heavier. Any thoughts?
Signature: A


Dear A.,
You have had an encounter with a Caddisfly in the order Trichoptera, and as we learned from BugGuide, there are:  “1,350 spp. in ~150 genera of 22 families in NA [North America]”
and we cannot say for certain how to classify it more specifically, though it does closely resemble several photos from the genus Psychoglypha that can be found on BugGuide.  Like you own observations, BugGuide notes that “Adults resemble moths, but wings are hairy instead of scaly.”  Larval Caddisflies are aquatic and they construct shelters, so they are commonly called Caseworms.  Interestingly, each species of Caddisfly Larva builds a different shelter, some of sticks, some of stones, some of shells and others from other materials.  According to bugGuide:  “Most species live in a mobile case constructed from plant material, algae, grains of sand, pieces of snail shells, or entirely of silk. The case is held together with strands of silk secreted by the larva. In some species the case is attached to a rock, log, or other underwater surface; a few species have no case and are free-living.  The case’s particular shape and construction material is distinctive of the family and/or genus, and can be used in identification. Example: Helicopyschidae larvae use sand grains to build spiral cases that resemble small snail shells.”

You are amazing! Thanks so much for the response. Mystery solved.

Location: Washington

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