Caseworm: Caddisfly Larva

Subject: Pond Insect
Location: Oak Harbor (Whidbey Island), WA
June 15, 2012 2:26 pm
We started seeing these ”thatched cocoon” things floating in our pond in May. At first I thought they were worms but as they emerged their legs became visible. I’ve never seen anything like it! Any ideas?
Signature: Cyaxtin

Caddisfly Naiad

Dear Cyaxtin,
Though it is commonly called a Caseworm, your observations that this Caddisfly Larva is not a true worm is correct.  Aquatic larvae are usually called Naiads.  This Caseworm will metamorphose into a winged Caddisfly, a mothlike insect.  This is an awesome photo.  Each species of Caddisfly makes a distinctive looking case because of both the form and the materials used.  The case serves as a shelter during its larval stage.

Thank you soooo much!! Fascinating little creatures! I very much appreciate your time!

Leave a Comment