Dryomyia lichtensteinii, a mosquito of Cecidomyiidae family, causes galls on back side of holm oak leaves. Such galls look like a 3×2 mm bump, 2 mm high on back of the leaves. Usually, one leaf has several galls. When number of galls is too much, then the leaf results distorted and rolled showing just its back. There is one larva inside every gall. A secretion of the larva promotes the development of the gall.
The adult is a small mosquito with long legs and hairy wings.
Dryomyia lichtensteinii may infest the cork oak as well.
Species of family Cecidomyiidae are known as gall mosquitoes because most of them really cause galls in plants. In addition to this frequent gall in holm oaks, other galls caused by Cecidomyiidae mosquito species are the bottle shape, orange coloured gall on top of beech leaves by Mikiola fagi and the gall at the tip of sprouts of junipers, by Oligotrophus panteli.
[photos Jordi Badia]