Male gnats often assemble in large mating swarms, or ghosts, particularly at dusk. Gnat larvae are mostly free-living, and some are aquatic. Many feed on plants, though some are carnivorous. Larval plant feeders (such as the Hessian fly larva) cause root, stem, or leaf galls to be formed by the host plant.
There are more than 30 Culicoides species of midges in Scotland. The biting species vary with habitat. The species C. impunctatus is the one you usually encounter in the Highlands. (Pictured here) Midges landing on my hat in quite big numbers, near Shieldaig, Wester Ross. Still evening in high summer so the conditions were just right.
P. papatasi are small, never reaching greater than 2-3 millimeter in length, and have the body covered with hair. Their flight, typical of sand flies, consists of short hops and, for the most part, with a reduced range. The life cycle, from egg to larval stages L1 through L4, pupae and adult takes approximately 3 to 4 weeks. The life span of adults is believed to be approximately 30 days.