Bluetongue is an infectious disease of ruminants-but severe disease usually occurs only in sheep-caused by a virus transmitted by Culicoides spp. (biting midges). Following recent epizootics (1998-2002) in the Mediterranean basin, "it can be said that the dreaded bluetongue is a viral emergent in Mediterranean ruminants". (Federation of American Scientists, October 2001). Culicoides imicola is considered the major vector in Europe but other Culicoides spp. could perhaps play a significant role in the epidemiology of bluetongue. As bluetongue could have huge economic importance, it appears essential to develop predictive models with the aim of improving and refining surveillance systems.