Species composition of mosquitoes collected in the Murray Valley of South-eastern Australia during an epidemic of arboviral encephalitis.

Mosquito activity at the height of an epidemic of arboviral encephalitis in the Murray Valley during the summer of 1974 was almost entirely crepuscular and nocturnal, but anecdotal evidence, indicated that day-biting Aedes species were also unusually prevalent during the first 4-5 weeks of the epidemic. Ninety-eight percent of the 138,359 mosquitoes captured in miniature light traps and by aspiration between 4th and 13th February, 1974, were Culex annulirostris, and 10 other species of 5 genera comprised the remaining 2%. In the one 'man-biting' collection 96% of 1,364 mosquitoes were Cx annulirostris. The overall capture rate for 51 light trap nights at 7 widely dispersed collecting sites was 2,675. At Barmah Forest 10 light trap nights yielded an average of 9,103 mosquitoes, with a maximum of 26,293 in one trap night.