Last modified: Jan. 29, 2020, 11:36 a.m.
A rare and local species in Belgium.
A white, sometimes sticky cocoon. Pupa pale yellowish brown.
The first generation larva lives in the stem, usually in the flowering part, causing a gall or swelling. Larvae of the second generation live in a seedpod. There can be several galls in one stem and even several larvae in one gall.
The full-grown larva chews out a neat hole in the side of the gall and leaves the gall in order to pupate amongst detritus on the ground in a white, sometimes sticky cocoon.
Two generations a year: from July till August, and again from September, hibernating, till May.