Aedes taeniorhynchus were collected on the wing at several times during the day and night, in Indian River and Brevard County, Florida. Nonblooded females were individually analyzed for fructose and glycogen. Fructose content of mosquitoes collected early in the morning and held without food during the day diminished to approximately the same level as in mosquitoes collected late in the afternoon. However, fructose content of mosquitoes collected before sunset and held without food overnight diminished greatly, whereas that of mosquitoes collected in the morning always exceeded that of evening collections. Maximum fructose content occurred within one or 2 hours after sunset. Apparently, these mosquitoes take little or no nectar during the day, and feed soon after the onset of darkness.