Individual female mosquitoes from field populations of Aedes aegypti, Culex nigripalpus and Coquillettidia perturbans were analyzed for sugar, glycogen and lipids. Controls were maintained in the laboratory for 7 to 10 days on 2% and either 10 or 20% sucrose. Mosquitoes held in the laboratory had significantly more glycogen and lipid than field-collected mosquitoes of the same species. Laboratory mosquitoes maintained on 10 or 20% sucrose contained more sugar than did field mosquitoes. Mosquitoes of the above species were collected at field sites in January, April, July and October and nutritional reserves were determined. Seasonal differences in reserves were documented in females of all species. However, even when reserves were at their highest in field-collected mosquitoes they rarely approached the reserves in mosquitoes of the same species maintained in the laboratory on 10 or 20% sucrose. Since laboratory-maintained mosquitoes are nutritionally different from those in the field, results of laboratory studies on flight performance, host attractancy, biting, disease transmission and oviposition behavior may be biased.
