Aphid aggregation

Chemical alarm signals operate when interacting individuals are aggregated or in close proximity. It is not unexpected, then, that such signals are well-developed in the social insects and relatively uncommon in pre-social species. Outside the social insects, chemical alarm systems are best developed in two homopteran groups aphids and treehoppers. In this chapter, we discuss alarm pheromones and their social context in these and other pre-social insects and suggest modes of their evolution. 

Aphid clusters result not only from females and their offspring but certain species aggregate following dispersal flights or disruption from clusters. Aestivating nymphs of Periphyllus acericola will reform in compact groups if... 

Dixon, A. F. G. and Wratten, S. D. (1971) Laboratory studies on aggregation size and fecundity in the black bean aphid. Aphis fabae Scop. Bull. Ent. Res, 61, 97-111. 

Way, M. and Cammell, M. (1970) Aggregation behavior in relation to food utilization by aphids. In Animal Populations in Relation to Their Food Resources (Watson, A., ed.) pp. 229-47. Sym. No. 18, British Ecological Society, London. 

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