Measurement of ‘Environmental Resistance' in the Australian Plague Grasshopper

Abstract

LABORATORY and field experiments have shown that the Australian plague grasshopper, Austroicetes cruciata Sauss, is well adapted to live in the particular climatic zone where it is found¹. An obligate diapause in the egg-stage ensures that the grasshopper produces only one generation each year². Eggs are laid during November and December (late spring and early summer), but never hatch before the following August or September. Thus the active stages are present during two or three months in the spring when the physical environment is least severe. For the remaining nine months, comprising the hot dry summer and cool wet winter, the insects are in the soil in the egg stage, which is well adapted to resist desiccation during the summer and high humidity during the winter.