Winter gnat

We don’t expect to see many insects on the wing in winter, but just a little sunshine draws out swarms of tiny dancers. These are winter gnats (Trichocera annulata and other Trichoceridae); delicate leggy flies which are dancing to impress the females.

Fast Facts

Latin name: Trichocera annulata

Notable feature: Small (8-10mm) long, thin legs, banded abdomen and unmarked wings.

Where in the UK: Widespread in woodlands, parks and gardens.

Though they are active year-round, Winter gnats are most noticeable in the colder months when the males perform their courtship dances. Swarms gather in areas that are kept warmer by the sun, such as woodland glades, riverbanks and above sun-warmed objects. Sometimes following people purely for the heat they give off (though they resemble mosquitoes they do not bite). In low winter sunshine, the reflective wings of the dancing swarms can make them appear like apparitions. In fact the gatherings are sometimes called ‘ghosts’

This act of gathering together to attract mates is known as ‘lekking’ and is thought to make them easier for females to find. Each male flies up and down to his own rhythm, but they cleverly space and pace themselves out to avoid colliding with others in the swarm. If threatened, they are quick to scatter and re-join nearby.

These swarms inevitably attract predators too. Small birds snap up the flies for a much-needed protein snack.

Once mated, the female lays her eggs amongst decaying vegetation, which the larvae feed on. When the adults emerge they are often attracted to electric lights and can be found on windows after entering houses. They do no harm indoors. Instead, this is a chance to appreciate their delicate beauty.