A new automatic device for recording the host-seeking behavior of mosquitoes was designed using photoelectric sensors. The host-seeking rhythms of several species of mosquitoes were recorded under laboratory conditions. Use of CO₂, in addition to heating and black color to activate mosquito flight, proved to be important for evaluation of the present recording device. The diel rhythms of nonblood-fed Aedes albopictus (Skuse), Aedes aegypti (L.), Culex quinquefasciatus Say, Culex tritaeniorhynchus Giles and Anopheles stephensi Liston females recorded by the device corresponded well with known flight and activity rhythms in field for the same mosquito species. This simple automatic recording device provided accurate information on the flight behaviors of colonized and field collected mosquitoes.