Novomessor albisetosus and N. cockerelli foraged most intensively in the evening and morning at soil surface temperatures between 20 C and 40 C. They were not active in the middle of the night and mid-day. In both species, colonies provided with supplementary seeds increased their foraging intensity. N. cockerelli colonies which were provided with high protein food (tuna fish) extended their foraging time and remained active until soil surface temperatures reached lethal levels. Nearly half of the natural forage of N. cockerelli was insects or insect parts which accounted for only 6.6% of the forage of N. albisetosus. Approximately 10% of the workers of N cockerelli entered and were apparently accepted by colonies other then their "home" colony. This study demonstrates the importance of both forage availability and forage quality as determinants of activity and forage selection of Novomessor sp.