Marching and Colour in Locust Hoppers in Relation To Social Factors

Abstract

Abstract1. Restriction of social contact in hoppers of Locusta migratoria migratorioides (R. & F.) leads to reduced marching, so that animals reared in isolation march very little, even when placed in a crowd. Various types of restriction have been studied in the laboratory. 2. Hoppers crowded in small cages did not march as vigorously as those reared crowded in large cages and reduction of density during rearing led to a further reduction in marching. 3. Hoppers crowded for part of the day or night marched as much as those crowded all the time, although they were not fully gregarious in colour. 4. Olfactory, visual and auditory contact between hoppers had little effect on marching. 5. Exercise increased marching performance a little in animals in which contact was restricted. 6. The full development of marching behaviour depended on tactile contact between hoppers during rearing. 7. The pigmentation, which likewise depends on social contact between hoppers, did not respond in the same way as marching.