Quantities of Food eaten by the Desert Locust,Schistocerca gregaria(Forsk.), in Relation to Growth

Abstract

The weight of fresh grass eaten by Schistocerca gregaria (Forsk.) on each day of its development from hatching until maturation of the adults was investigated. Hoppers in all instars ate on the average about one gram per gram body-weight per day on the middle days of the instars and the adults ate approximately half-a-gram per gram body-weight each day. The percentage of food assimilated, calculated from the dry faeces and estimated dry weight of food eaten, falls from about 78 in the first to 35 in the fifth instar. There were some indication that the food consumption per hopper increases with the number of hoppers per cage.The weight of wheat bran eaten by hoppers was also investigated. The amount eaten by hoppers on the middle day of the first instar is approximately the same, in relation to their body weight, as that eaten per day just before and just after moulting by those in the fourth and fifth instars. More is eaten in the middle of these instars.Measurements of weights and lengths of males and females in the hopper instars and of the weights of adults showed that in the course of their development females become progressively heavier and larger than males. The weight of a newly-hatched hopper is about 10 mg.; a female fledgling weighs about 2 gm. and a male 1·5 gm. Hoppers are approximately 1 cm. long on hatching, and males on reaching maturity are about 4·5 cm. long and females about 5.0 cm.