Field Evidence of Density-governing Reaction in Sminthurus viridis (L.)

Abstract

THE limits of distribution of the lucerne flea in Western Australia are determined primarily by rainfall and temperature¹. Thus the infested area is restricted to a comparatively small section in the south-west corner of the State, where the occurrence of the active stages of the insect is determined primarily by favourable conditions of rainfall and temperature. In most places the high temperatures and low rainfall of the summer period cause the active stages to disappear completely, continuity of the species being maintained by the highly resistant æstivating eggs.