The possible vectors of myxomatosis amongst rabbits in a typical mountain environment in eastern New South Wales have been investigated. The disease was established in an isolated population of rabbits and the course of its fluctuations followed through a period of two and a half years, involving two large-scale reductions in rabbit density. Of over 60 species of blood-sucking flies encountered, 9 species of Culicidae, 2 of Simuliidae, 3 of Ceratopogonidae, and 1 of Tabanidae have been shown to feed on rabbits. Two recoveries of myxomatosis virus have been made from mixed collections of Aedes queenslandis and A. alboannulatus. The relative importance of the species known to attack rabbits is discussed in relation to the transmission and maintenance of the disease. Information on host preferences and the feeding, resting, and movement of adults is given. Possible factors influencing the autumn incidence of the disease on the eastern coast and tablelands area of New South Wales are discussed, and further means of exploiting myxomatosis towards the control of rabbits in specific environments are suggested.