The Physical Basis of Insect Drift

Abstract

THE writer in the issue of NATURE for September 5, 1925, summarised available data in regard to insect drift and only incidentally alluded to the meteorological phases. Very recently the occurrence of hundreds of thousands or even millions of black aphids, Dilachnus piceœ Panz., and a flower fly, Syrphus ribesii Linn. (C. S. Elton, Trans. Ent. Soc. Lond., pp. 289–299, 1925), on the ice-covered wastes of North-East Land, Spitsbergen Islands, north latitude 80°, has renewed interest in the subject, particularly as these insects must have drifted more than 800 miles near the extreme north. This could scarcely have been a movement in response to some strong instinct, and the same is very probably true of the Coccinellids recorded very recently from the crater of Vesuvius (Ent. Record and Journ., Variation 37, 143, 1925).