One aspect of an intensive study of arboviruses and insect vectors at Beatrice Hill, N.T., was to determine the hosts of the insects by identifying the source of their blood meal. The collection methods included buffalo bait, calf- and chicken-baited Magoon traps, truck traps, light traps and collecting from insect resting places. Blood meals were identified by precipitin and haemagglutination-inhibition tests. Fifteen species of biting midges, mostly Culicoides spp., and 24 species of mosquitoes were represented in the collections, and the blood meals within 75% of some 11,000 insects were identified. The majority, 97.7%, of the blood meals were mammalian in origin, 76% being bovine and 17% marsupial. A significant proportion of the blood-fed mosquitoes from Magoon traps had fed on hosts other than the bait animal or collector. Double feeds were detected in 1.1% of the insects in which the source of the blood meal was identified. It was possible to draw conclusions about the feeding habits of most of the insect species.