Last modified: March 20, 2021, 10:12 a.m.
A very rare and local species in the southern part of Belgium. May be extinct
A. aeratella is a very small dark grey moth with a wingspan of 9–10 mm and having a purple shine when fresh. The antennae are rather short: nearly half the size of a forewing.
The yellow caterpillar lives from July till May and hibernates in a gall.
The presence of the larva induces the formation of a fusiform and often reddish gall of about 15 mm on the hostplant.
See also bladmineerders.be.
When young, the caterpillar lives on and inside a flower of the hostplant causing the formation of a reddish spindle-shaped swelling. Later on, when full grown, the caterpillar cuts the gall loose, leaves the flower and moves around on the stem of the plant carrying the gall with it. The gall, with the larva inside, can be found standing mostly perpendicular on the stem. Eventually, the larva pupates inside its gall in May.
The adults are also active during daytime.
The adults are on the wing in June and July.
This species lives almost exclusively on Polygonum aviculare (common knotgrass) but also Polygonum arenarium, P. patulum, P. romanum and, even more rarely, Persicaria lapathifolia are accepted.
Although the hostplant is found almost everywhere in Belgium, A. aeratella is, at present, only known from LX.
The species has probably a preference for limestone areas.