Culicoides biting midges (Diptera: Ceratopogonidae) are biological vectors of several livestock pathogens of international significance, among which bluetongue virus (BTV) currently has the highest profile in the European Union. The flight activity and dispersal of Culicoides can be one of the factors that determines the introduction and spread of the viruses that they transmit. The potential for long-distance dispersal of Culicoides is usually inferred from disease outbreaks on islands, where confounding movement of viraemic ruminant hosts, whether illegal or legal, can be excluded from epidemiological investigations (Sellers 1980, Calistri and others 2003, Alba and others 2004, Gloster and others 2008). Studies of movement over land masses are less straightforward due both to the confounding movements of ruminants and to intrinsic difficulties in modelling wind movements over topography (Sellers 1980, Murray and Kirkland 1995, Braverman and Chechik 1996, Ducheyne and others 2007). Culicoides have been caught at a range of heights in the air (Glick 1939, Hardy and Cheng 1986, Johansen and others 2003), including some at over 1.5 km in the samples reported by Glick (1939), although the results were not always quantified. While long-distance windborne dispersal of small insects is commonly referred to as ‘passive’, this term is misleading, as flight is actively initiated at take-off and ascent, and …