The Biology and Control of the Sugar-cane Chafer Beetles in Tanganyika

Abstract

The principal pest of sugar-cane in northern Tanganyika is the Red Cane Beetle, Cochliotis melolonthoides (Gerst.) (Melolonthidae). Descriptions of adults and larvae of Cochliotis and of allied beetles found in the same area are given.The bionomics of Cochliotis have been studied in the field over two seasons. The life-cycle is annual with adult swarming in early October and a season of maximum larval damage in July–August.The intensity of infestation and the nature of the losses are discussed, and the mortality factors which act upon Cochliotis in nature are reviewed.Cultural control measures suggested include the deferment of planting until July to October, when larval activity has waned; introduction of quick-maturing varieties, mechanically cultivated so that long ratooning can be gradually eliminated; regulation of the water table by control of irrigation, and the trial of resistant varieties. The Mauritius varieties M. 134/32 and M. 165/38 are suggested in this connection.Biological control is discussed and a review of the parasite species that might possibly be introduced is made largely from the writer's Mauritius work on Clemora smithi (Arr.).Experiments in the chemical control of Cochliotis are described and the final recommendation is the application at planting of ½ lb. per 50 ft. of furrow of a BHC powder containing 2·5 per cent, of γ BHC. This practice has been adopted by the infested estate with successful results in virgins and first ratoons.Further work is suggested on the chemical protection of second and later ratoons by surface application of BHC or aldrin.