Offshore Migration and the Collapse of Outbreaks of the Australian Plague Locust (Chortoicetes Terminifera Walk.) In South-East Australia.

Abstract

High levels of night-flight activity of the Australian plague locust, Chortoicetes terminifera Walker, occurred on at least five separate occasions during the 1973-74 plague in south-east Australia and resulted in episodic, large-scale invasions at night of parts of southern New South Wales, Victoria and South Australia from more northerly breeding areas. The plague did not, however, reach the severe and damaging levels expected in the areas invaded, since on at least three out of five occasions nocturnal migration continued offshore and resulted in extensive mortality. The relationship between migration patterns and synoptic circulation is shown for each of the five situations, with special reference to the use and limitations of wind trajectories for estimating high-altitude displacement of locusts at night.