Gall midges (Diptera: Cecidomyiidae) of Denmark.
The Danish fauna of the family Cecidomyiidae comprises 286 named species and 21 species identified to the genus level only, which gives a total of 307 Danish gall midge species. Seventy-three species are thought to be new records for Denmark. The occurrence of each species has been verified by examination of voucher specimens in collections, or is based on critically reviewed literature data. The known fauna has been recently enhanced by the addition of species collected by J. Jørgensen on Læsø during 1980-2003 and in northeastern Sjælland in 2002 by M. Skuhravá and V. Skuhravý. A total of 275 species (89%) belong to the subfamily Cecidomyiinae, 14 species (5%) to the subfamily Porricondylinae and 18 species (6%) to the subfamily Lestremiinae. Cecidomyiinae are predominantly phytophagous, Porricondylinae and Lestremiinae phytosaprophagous. Phytophagous species causing galls or living free in flower buds are associated with 190 host plant species of which 60 are trees and shrubs and 130 herbaceous plants; 8 species are inquilines in galls of other insects; 19 species are predators attacking other gall midges, aphids and other small insects and mites; 4 species are mycophagous. Most species are native members of the European fauna, but 4 species are immigrants from other regions. Dasineura gleditchiae, Janetiella siskiyou and Resseliella conicola are immigrants from the Nearctic Region and Rhopalomyia chrysanthemi from southeastern Asia. The Danish record of Resseliella conicola is thought to be the first record in Europe. An annotated list of Danish gall midge species and their host plants is given.