1.Masses of Rickettsia were frequently found in mosquitoes (Aedes aegypti) which were known to be infected with the virus of dengue fever. No Rickettsia were found in control mosquitoes.
2.A contaminating protozoon resembling developmental forms of Lankesteria culicis occurred in some of the control mosquitoes. This contaminating organism can, under certain conditions, offer some confusion in the study of Rickettsia in smears. In continuing the examination of mosquitoes for Rickettsia it is obviously desirable to protect them from contamination with any confusing microörganisms.