Aggressive behaviour in the ant, Formica fusca

Abstract

1. 1. The factors eliciting and influencing aggressive behaviour in the ant, Formica fusca, have been investigated. 2. 2. Seizing and dragging are types of aggressive response. Threat is shown to be an aggressive response which may be regarded as an incomplete seizing movement. Arguments are presented to show that threat, seizing and dragging represent increasing strengths of aggressive motivation. 3. 3. Four types of response may typically be shown towards aliens—the 3 aggressive responses and licking. The response pattern towards aliens is different from that towards returning nest-mates. More licking is shown towards the latter. 4. 4. Licking correlates negatively with total aggressive responses, but is more closely linked with threat than with seizing or dragging. The relation of licking with aggression is discussed. 5. 5. Various factors besides colony odour evoke or influence aggression. Thus, both temperature and hunger affect it. The situation “ant-entering the-nest” probably evokes aggressive responses and licking. However, colony odour remains the most potent stimulus to aggression. 6. 6. There is no evidence of an inherent difference in aggression between colonies. Increased aggression is shown at higher temperatures. Hunger also increases aggression and the significance of this is discussed. Other factors such as the presence of larval brood probably affect aggression as well. 7. 7. The origin of distinctive colony odours is discussed. Metabolic differences induced by different diets play only a small role in producing these odours in ants.