Abstract
Adults of the cabbage root fly (Erioischia brassicae (Bch.)) fed on 0·1% tepa in 10% sucrose solution during the second and third days after emergence laid over 95% sterile eggs. Nearly complete sterility was also obtained from females fed on 0·l% tepa for two days between mating and oviposition. Tepa at 0·1% did not affect longevity of either sex or the competitiveness of treated males, although at higher concentrations longevity was reduced. When flies were enclosed in a large field cage and provided with food baits containing 0·1% tepa, sucrose and leucine along a hedgerow, 70% of the eggs laid were sterile.