On the flight of the wheat gall-midges Contarinia tritici (Kirby) and Sitodiplosis mosellana (Gehin) (Dipt., Cecidomyidae) in relation to wind direction and wheat fields.
Direct observations and catches in wind traps near wheat fields in the north of the German Federal Republic (Kiel) in 1971-75 showed that females of Contarinia tritici (Kby.) and Sitodiplosis mosellana (Geh.) move from their emergence sites to wheat fields predominantly downwind above the crop level and upwind below the crop level. Almost all the females of C. triciti and S. mosellana caught flying downwind above the crop level were fully gravid, while those caught flying upwind had mostly laid some of their eggs. It is confirmed from these results that the cecidomyiids perform a so-called transit flight downwind and an appetitive flight upwind, though the two can change repeatedly. In most cases, the edges of wheat fields were more heavily infested by larvae than the centres. The parasite Pirene penetrans (Kby.) appeared to have similar flight habits, preferring to fly with the wind.