Experiments on the control of the Lucerne flea (Sminthurus viridis (L) and the Red-Legged earth mite (Halotydeus destructor (Tuck.)) in pastures in Western Australia.

Abstract

Experiments with BHC, chlordane, and parathion against the lucerne flea (Sminhurus viridis (L.)) and the red-legged earth mite (Halotydeus destructor (Tuck.)) in pastures are described. All insecticides were applied by means of a low-volume boom spray delivering 5 gal per acre. BHC applied at the rate of 2 lb 50 per cent. dispersible powder per acre had no effect on the lucerne flea population but killed approximately 90 per cent. of the earth mites present. Chlordane applied a t the rate of ½ lb per acre achieved no control of either pest. Parathion applied at the rate of ¼ pt of 20 per cent. emulsion per acre gave practically 100 per cent. control of lucerne fleas. Its residual effects were negligible and fleas hatching from eggs laid prior to spraying were not harmed. Equally good immediate control was achieved by applications of parathion at one-half the above concentration. The addition of DDT to the spray ensured the destruction of all earth mites as well as the lucerne flea. DDT gave no evidence of control of the lucerne flea in previous experiments. The experiments show that parathion is a highly effective insecticide against the lucerne flea but for maximum efficiency it should be applied early in the season before any eggs have been laid. The toxicity of the parathion sprays to grazing stock is discussed.