Bibio marci Bibionidae. (Linnaeus, 1758) Common name “St. Marks Fly”
Named because it often appears close to St. Mark’s day (April 25th)
Family: Bibionidae (20 species of this fly are found in the UK)
Like other members of the family they have short stout antennae’s inserted below the eyes.
The St. Mark’s Fly is a species of “True Fly” and are also known as “Hawthorn Flies”
Females 14mm in length, Males 12mm in length.
This is a very common fly, appearing late in April. Both sexes have a short life of around a week when on wing. Most of the St. Marks Fly life is spent as larvae, feeding on rotten vegetation, roots and grasses; during the autumn and winter months. The males emerge a few days before the females, the following spring.
The male’s eyes are divided by a groove, interestingly they have separate connections to the brain. This enables them to locate a female and at the same time they can locate their position, to hover above the ground.
The adults are considered important early pollinators for fruit trees and other plants as they feed on the nectar. Although they can be annoying when they fly in large swarms, landing on anything that crosses their flight-path; even people.
Breeds: After laying her eggs in the soil or rotting vegetation the female soon dies
Habitat: Found close to Woodlands, Country and Urban Gardens, Wetlands, Farmlands, unkept grasslands, Heathlands and Moorlands.