THE SWARMING BEHAVIOR OF THE SCOTTISH BITING MIDGE, CULICOIDES-IMPUNCTATUS (DIPTERA, CERATOPOGONIDAE)

1. Swarms of Culicoides impunctatus males were examined in the field in Scotland. Most swarms were close to midge emergence/breeding grounds over a variety of vegetation, some of which clearly acted as swarm markers. Low light (0-1000 lux) and still/humid conditions favoured swarming. 2. Swarm size ranged between less than 10 and more than one thousand midges. The modal size was 200 individuals. The smallest swarms were usually columnar in shape and the larger swarms ovoid. 3. Midges behaved individually within swarms, moving in an elliptical manner characteristic of other dipterans in swarms. 4. Swarms were classified as either 'persistent' or 'transient' in terms of their shape, size and stability. Wind was the most influential factor in disrupting swarms. 5. Swarms were confirmed as mating sites for C.impunctatus.