Diel activity patterns of blood-seeking anthropophilic mosquitoes in central Sweden.

1. Blood-seeking diel activity cycles of mosquitoes are described from 24 h landing catches on human bait in a field and a forest habitat during June-August in central Sweden. 2. Daytime activity in the field was low or absent, whilst in the forest activity was relatively even throughout the diel. 3. In both habitats, activity peaks generally occurred about sunset and sunrise and were more distinct in the field than in the forest. 4. Data from this and other studies show that, in general, Aedes cinereus Meigen feeds at night in field-type habitats and Ae.communis (DeGeer) during the diurnal-crepuscular period in forest and woodland habitats. 5. Although abundant in the study area, Anopheles maculipennis Meigen sensu lato, Culex pipiens L., Cx torrentium Martini and Culiseta morsitans (Theobald) were not caught on the human bait. This is because, in central Sweden, An.maculipennis s.l. is mainly feeding in animal sheds whereas the others are ornithophagous. 6. Ae.geniculatus (Olivier) was recorded from central Sweden for the first time. 7. Blood feeding success (proportion of mosquitoes that managed to obtain blood from the human bait) was significantly greater in Ae.cinereus (14.9%) than in Ae.punctor (Kirby), Ae.communis and Ae.annulipes (Meigen) (2.8-0.7%). 8. The data are interpreted in relation to the transmission of Ockelbo disease (caused by Sindbis virus) and tularaemia in Sweden.