| Summary: | Voltinism was determined in various populations of Aedes campestris Dyar and Knab from different locations. The Winnipeg population was 100% multivoltine, whereas the Churchill population was 64% multivoltine, 36% univoltine. Saskatoon and Estevan populations were 99% multivoltine, 1% univoltine. A laboratory colony of A. campestris was successfully maintained in a 120-x 120-x 210-cm cage for 3 generations. The optimum temperature for development and survival of A. campestris in the laboratory was 23oC. The time required for larval and pupal development was 9 and 3 days respectively at 23oC. Ovarian development of blood-fed females was also studied at 23oC, and females were able to complete follicular development within 3-4 days. Variation in autogeny was observed in populations from different geographic regions. In the Churchill population, 45% of the females were able to develop some autogenous eggs 15-20 days after emergence. In a. campestris from Saskatoon, 13.9% of the females developed a few autogenous eggs. There was no significant difference between the number of eggs laid by females fed 1, 2, or 3 blood meals in the Saskatoon or Estevan populations. The Churchill females fed 3 blood meals produced more eggs than those fed 1 blood meal. At 23oC the critical period for induction of egg diapause in the Saskatoon population occurred between 13L:11D and 14L:10D. Egg diapause in the Saskatoon population was obtained after 10-14 days of exposure to a short photoperiod (<14L:10D). The greatest percentage of diapause occurred after 30 days. Long photoperiod (16L:8D) terminated egg diapause at 23oC in the Churchill population and the percentage of termination increased significantly at 30oC. The larval and adult stages of A. campestris and the related species, A. dorsalis (Meigen) and A. mediolineata Ludlow, are described. This study confirmed the separate species status of A. melanimon from A. dorsalis and reveals an older name than A. melanimon, namely mediolineata Ludlow 1907 which was previously a synonym of A. dorsalis. The key for species and the comparisons of various characters of first and fourth instar larvae, and male and female adults are listed to point out the reliable characters for separating each species. The distribution of the three species in North America is illustrated in a map.
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