A comparison of the response to aggressive behaviour in two species of ants, Formica fusca and Formica sanguinea

Abstract

1. (1) The escape activity, flight responses and aggression shown by entrants to nests are discussed. Both aggression and alien colony odour evoke flight responses and escape activity. Flight and aggression are mutually inhibitory in an individual. 2. (2) Fusca frequently shows a flight response, sanguinea rarely does. Sanguinea shows a particular type of palpation called “entrant palpation” in aggressive situations, which fusca does not. 3. (3) The nature of entrant palpation and its causal relations are discussed. It can be distinguished from palpation associated with food-sharing by certain characteristics, e.g. it seems to be evoked by aggression shown towards the palpating ant. Nevertheless the links with food-sharing are strong. It does not seem to have a conciliatory effect so that its function is doubtful. It is suggested that it is a modified form of food-sharing behaviour which is evoked in aggressive situations and which may lead to offering of food by the palpating ant if there is enough food in the crop to allow this behaviour. 4. (4) The significance of the differences between fusca and sanguinea are discussed briefly, e.g. the rarity of the jerking response in sanguinea and the lesser aggression this species shows to aliens of the same species entering the nest.