Last modified: Nov. 22, 2024, 12:44 p.m.
A common species throughout Belgium.
Native
In parthenogenetic species, adult females are apterous. They can be distinguished from females of Dahlica lichenella by the foreleg which in D. triquetrella always has 5 tarsal segments, whereas in Dahlica lichenella there are only 4 tarsal segments which are sometimes fused.
A cross-section of the case is triangular, this character distinguishes this species from Dahlica lichenella in which the cross-section of the case has a round shape. It is made from silk, and covered with fine sand, soil, and even particles of dead insects. Other Dahlica species do not include insect particles in their case.
One generation a year with males flying from March till May.
The larva lives on lichens and algae growing on tree-trunks, rocks and old walls. This is supplemented with dead insects for a successful development.
Preferably in xerothermic habitats in forests with a lot of Fagus, but also in meadows with a lot of undisturbed lower vegetation.