Some factors governing the entry of Culicoides spp. (Diptera: Ceratopogonidae) into stables.

The entry of Culicoides species into stables was examined by comparing the numbers of midges caught with identical light-traps under different conditions. The comparison was made between collections made inside an empty stable, a regularly cleaned stable and a dirty stable and those made outside the stables in a sleeping space open on two sides. The work was first done in the presence of cattle and sheep in adjoining paddocks and then repeated in their absence. A positive correlation was found between the numbers of C. imicola females caught out of doors and inside a clean stable. Removal of the cattle and sheep resulted in a reduction in the numbers of C. imicola caught inside and outside the stables. In contrast, the numbers of Culicoides spp. that prefer to feed on birds was not affected by the removal of the cattle and sheep. Their entry into the stable was proportionate to the size of the entrances into the sleeping space and the size of the stable door and presumably occurs passively. On the other hand, the numbers of C. imicola females entering the same stables were somewhat enhanced by the presence of horses inside the stables and by odours associated with dirty stables.