Caste and age polyethism was investigated by way of newly developed sampling methods used in field colonies ofM. bellicosus. Major workers make up 70% of foraging populations, whereas minor workers are predominant in spontaneous construction (97%), emergency construction (78%) and attendance of the queen (85%). The only task correlated with a high rate of soldiers (17%) is emergency construction. The composition of fungus—growing and water—carrying populations differs only slightly from that of the population as a whole. Foraging and building populations consist exclusively and water carrying populations mainly of old workers. In fungus growing and queen attending populations both old and young workers are present.