noun
caddisfly larva; caddis worm
Refers to the aquatic larva of the caddisfly, known for building protective cases from sand, stones, or plant material. Also called 飛螻蛄 (とびけら) for the adult insect.
See also: 飛螻蛄
川底の石をひっくり返すと、いさごむしがくっついていた。
When I turned over a stone on the riverbed, a caddis worm was attached to it.
いさごむしは小石や砂で巣を作る。
Caddis worms build cases out of small stones and sand.
Refers to the adult caddisfly, while いさごむし specifically denotes the larval stage.
The derivation is uncertain. The kanji 石蚕 literally means 'stone silkworm', likely referring to the larva's stone-like case.