OBSERVATIONS ON THE BEHAVIOUR AND MORTALITY IN COCCINELLIDAE BEFORE DISPERSAL FROM THE EGG SHELLS.

WHEN ladybird beetles are numerous on bean plots and have laid many egg batches, cannibalism may be an important cause of mortality of the immature stages ; larvae dispersing from the eggs in search of food encounter and eat unhatched eggs and newly-hatched larvae clinging to the egg-shells before they are old enough to disperse (Banks, 1955). Even when coccinellid populations are low there is a certain degree of mortality during the egg stage, for some eggs are apparently infertile and some unhatched larvae may be destroyed by larvae already hatched from the same batch. Hawkes (1920) observed that some eggs of Adalia 2-pnctata hatched earlier than others and that approximately a quarter of the larvae were eaten before dispersal. Smee (1922) also noted that newly-emerged larvae attacked unhatched eggs and that some eggs were infertile. Johnssen (1930) recorded that, on the average, 40 per cent. of the eggs of 9 batches of Goccinella 7-puwtata and only 6 per cent. of eggs of 9 batches of A. 2punctata did not hatch, but he did not express the mortality as infertile eggs and those in which larvae had developed. He noted that larvae after hatching frequently ate the empty egg-shells, infertile eggs and larvae which for some reason did not emerge. The mortality in the egg stage in Coccinellidae is discussed here with reference to three common species of bean plots, Coccinella V-punctatu L., Aclalia 2-punctata (L.), and Propylea 14-punctata (L.).