The bluetongue emergence and spread in Western Europe in 2006-2008, having disastrous consequences on livestock production, showed the unexpected ability of Palaearctic Culicoides species to transmit intensively the virus. Some aspects S68 Abstracts of Culicoides bionomics remain unclear mainly due to methodological concerns (identification or trapping and sampling difficulties). Our aim was to describe the circadian biting activity of Culicoides species and their endo/exophagic behaviour. Culicoides were collected in an experimental station of western France using 2 drop-traps and 3 suction traps each baited with 4 sheep, during 6 collections of 24 hours. Both traps were localized in a pasture and a semi-closed sheep pen; a suction trap was situated in an open stable. The experiment was repeated in spring, summer and autumn 2010 to analyze seasonal fluctuations. Individuals were morphologically identified to species level; sex and female physiological stages were recorded and sibling species were molecularly identified. A total of 907 Culicoides (874 females, 33 males), belonging to 13 species, was collected during spring and summer (autumn collections are under process). During both seasons, collections were maximum in the pasture (99% of total catch in spring and 94% in summer, with inter-specific variations) and during the sunset (76% and 89% of total catch 2 h around the sunset). These results clearly illustrated the Culicoides exophagic behaviour and confirmed that most of the activity occurred around the sunset for spring and summer. This understanding has direct consequences for the protection of domestic animals against Culicoides biting and the development of vector control strategies. (Texte intégral)