Distribution and Behaviour of Adult Ladybird, Harmonia axyridis PALLAS (Coleoptera, Coccinellidae), around Aphid Colonies

Field investigation was performed to clarify the mode of living in the predacious ladybird, Harmonia axyridis PALLAS, around aphid colonies. The number of beetles was positively correlated with the prey density. Their distribution pattern, however, was clumped even among trees infested equally by aphids. The marked sexrelated differences in behaviour were found : the female was usually resting or feeding, while most males were walking restlessly. Behaviour of males was considered as that for mate-searching, and probably regulated the distribution pattern in this beetles as well as the prey density.