JOINTWORM
strawworm, jointworm
(noun) larva of chalcid flies injurious to the straw of wheat and other grains
Source: WordNet® 3.1
Etymology
Noun
jointworm (plural jointworms)
The larva of a hymenopterous fly, Tetramesa tritici, found in gall-like swellings on wheatstalks, usually around the first joint.
Source: Wiktionary
Joint"worm`, n. (Zoöl.)
Definition: The larva of a small, hymenopterous fly (Eurytoma hordei),
which is found in gall-like swellings on the stalks of wheat, usually
at or just above the first joint. In some parts of America it does
great damage to the crop.
Source: Webster’s Unabridged Dictionary 1913 Edition