Many Holarctic genera of trees and shrubs are host over much of their ranges to particular genera of Cecidomyiidae. As examples, willows host gall midges of Rabdophaga and Iteomyia, oaks host Macrodiplosis and Polystepha, and birches host Semudobia in both the Nearctic and Palearctic Regions. So many instances of this pattern are known for gall midges that when a gall midge genus is recorded from only part of the range of a Holarctic plant genus, the partial absence may be suspected to reflect a lack of collecting. There are exceptions, one being beech. This tree is infested by gall midges of the genus Mikiola in Europe and Japan but apparently not in North America. Mikiola may once have occured in North America and become extinct due to the relatively narrow bottleneck beech passed through during the Pleistocene when it was restricted to southern North America.
Gagn , Raymond J.; Moser, John C. 1997. Celticecis, a Genus of Gall Midges (Diptera: Cecidomyiidae), Newly Reported for the Western Palearctic Region. Proceedings of the Entomological Society of Washington 99(4): 756