Aerial dispersal ofScelio fulgidus [Hym.: Scelionidae], parasite of eggs of locusts and grasshoppers [Ort.: Acrididae]

Scelio fulgidus Crawford, a hymenopterous parasite of eggs ofAcrididae, was discovered in samples of the aerial fauna, collected at 100–300 m altitude over grassland at a site in central western New South Wales at 2 sampling periods in October/November 1979. The parasite was recorded throughout the day in conditions of convective uplift suggesting that extensive diurnal dispersal occurred on the prevailing wind at distances varying from 100 to 300 km per day. Take-off at dusk of its major host, the Australian plague locust (Chortoicetes terminifera Walker), was observed in one period and direct aerial sampling at 100–300 m altitude subsequently confirmed the presence of this locust in the upper airflow at night. The mean wind vector did not differ greatly between day or night during this sampling period, suggesting that parasite and host were dispersed independently over the same general area by prevailing winds. Aerial dispersal provides a new explanation of the parasitism byScelio of egg beds of immigrant swarms of the plague locust in areas where hosts were previously absent.