Colour variation and polyethism of the soldier caste in the termite Macrotermes bellicosus

Based on abdominal colour three categories of major soldiers were found in Macrotermes bellicosus (Smeathman) (Isoptera: Termitidae). The three main c olour types, yellow, red and brown are due to the colour of the defence-sec retion stored in the labial gland's reservoirs. The order of these categori es correlates with the uric acid titres of the whole individuals. It is con cluded that colour could be used as a label for the relative age of a soldi er. Age dependent polyethism was observed in soldiers: the individuals of t he highest age class were the only ones leaving the nest to accompany the f oraging workers, whereas all age categories were found inside the nest. Aft er a significant loss of old individuals younger individuals show flexibili ty by replacing the missing outgoing nestmates. Caste regulation takes plac e by an increased rate of soldier development.