Erynia aquatica(Anderson and Ringo) (Zygomycetes: Entomophthoraceae) was discovered infecting wildAedes fitchii(Felt and Young) (Diptera: Culicidae) pupae in snowpools in Upstate New York. Conidia from infectedA. fitchiipupae were used to inoculate laboratory-reared, healthyA. aegypti(L.) pupae. A total of 10.7% of the adultA. aegyptithat emerged from these pupae died from the mycosis and were filled with the resting spore stage ofE. aquatica. Mature resting spores were round, thick walled, and 31.3 ± 3.7 μm in diameter. Resting spores contained an average of 13 ± 2.8 nuclei per resting spore. Numerous rhizoids grew out of the cadavers of infected adultA. aegypti. Rhizoids varied in width from 8.4 to 21 μm and were up to 2,000 μm long. AdultA. aegyptidied from the mycosis between 8 and 17 d after inoculation. The only reproductive stageE. aquaticaproduced in infected adultA. aegyptiwas the resting spore stage. The life cycle ofE. aquaticais unusual for the Entomophthoraceae, because the pathogen produces conidia in immature hosts and resting spores in adult hosts.A. fitchiiandA. aegyptiare new host records forE. aquatica.