Natural mortality of eggs of the black bean aphid, Aphis fabae Scop., on the spindle tree, Euonymus europaeus L

SUMMARY Egg mortality of Aphis fabae Scop, ranged from 18 to 73% on individual bushes of Euonymus europaeus L. at different sites in Hertfordshire during the winters of 1958?59 and 1959-60. Field and laboratory experiments indicated that the average mortality is unlikely to exceed about 40% and is probably relatively unimportant in limiting subsequent increase to pest density. Winter temperatures in. Southern England do not harm eggs except perhaps at hatching time. Some eggs are destroyed by Anthocoridae and by birds. Others either fail to develop, or develop fully but fail to hatch, even when the weather is apparently favourable and natural enemies are absent.