Diel activity and preferred landing sites in C ulicoides biting midges attacking Fjord horses

In the summer of 2014, in the central part of The Netherlands, C ulicoides spp. ( D iptera: C eratopogonidae) attack rates, biting rates, and preferred landing sites were determined for a pair of Fjord horses maintained permanently at pasture in an area devoid of cattle. Eleven body regions of the horses were screened for midges, each region sampled randomly for 5 min using a handheld mouth aspirator (pooter). Observations were confined to the hour immediately before and after sunset. C ulicoides spp. were obtained from every body region, of which the four most abundant species – C ulicoides chiopterus ( M eigen), C ulicoides punctatus ( M eigen), the species complex C ulicoides obsoletus ( M eigen), and C ulicoides dewulfi G oetghebuer – all were proven or potential vectors for arboviral diseases in livestock. C ulicoides spp. activity was distinctly bimodal across the day, surging at sunset and 1 h after sunrise. Midges were inactive between 11:00 and 16:00 hours, these hours marking the time of day when horses can be pastured most safely but, thereafter, to avoid escalating attacks, would have to be stabled protectively. Around sunset, the mean attack rate of the four most abundant species ranged from 3.0 to 11.7 midges per min; of these, C . dewulfi and C . chiopterus were reared out of the dung of experimental horses. The Netherlands is home to the world's densest horse population (11 per km 2 ), of which half are estimated to stay outdoors permanently with no access to protective housing. In the absence of a preventive vaccination policy, it is difficult to envisage how horses in northern Europe will be protected from infection during an outbreak of a C ulicoides ‐transmitted disease like African horse sickness.