Several Culicine mosquito species not previously recorded as being naturally infected by the protozoan parasite, Lankesteria culicis, were exposed to this parasite under controlled laboratory conditions. In addition to Aedes aegypti (the natural host of L. Culicis), infections were established in test populations of Aedes epactius, A. sollicitans, A. stimulans, A. vexans, Culiseta inornata and Psorophora columbiae. L. culicis failed to infect Culex pipiens quinquefasciatus and C. salinarius. Host responses to the infections are described and discussed.