Unlike domesticated European honey bees, Africanized honey bee (AHB) colonies can be extremely defensive. Extremely defensive colonies appear to practice territorial defence wherein members of the colony aggressively patrol and defend territories that extend well beyond the nest entrance. These territories expand and contract in response to frequency of disturbance. Organisms that employ aggression in their defence of territory normally employ a dramatic signalling behaviour designed to repulse intruders. If successful, fighting is avoided. Perhaps the most dramatic signaling behaviour employed by highly defensive AHB to maintain their territory is ‘head butting'. Since butting is an easily recognized element of the repertoire of highly defensive honey bee colonies, anyone encountering bees engaged in butting should recognize the behaviour as a warning that they have entered the territory of a highly defensive colony and quickly retreat to avoid further harm.