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Twin-lobed Deer-fly

Twin-lobed Deer-fly ©Les Binns

Twin-lobed deer-fly

Many of us have felt the painful bite of the Twin-lobed deer-fly (a 'horse-fly') while out walking in damp grasses or woods. But mostly, it prefers to feed on the blood of cows and ponies, often becoming a pest.

Scientific name

Chrysops relictus

When to see

May to September

Species information

Statistics

Length: 1cm
Common.

About

The Twin-lobed deer-fly is a species of horse-fly and, as such, the females have sharp, biting mouthparts and feed on the blood of large mammals, such as cows and ponies, but will also happily drink the blood of humans. The males lack these mouthparts, so feed on nectar. Females wait in shady areas for their prey to pass-by, locating it by sight with their large compound eyes. The eggs are laid on stones and plants, or in mud, close to water. When the larvae hatch they fall on to the damp earth where predate other invertebrates. This biting insect can be a real nuisance during the summer, especially in hot, thundery weather.

How to identify

Up-close, the Twin-lobed deer-fly is a beautiful horse-fly, with a yellow-and-black body, patterned wings and iridescent green-and-red eyes. There are 30 species of horse-fly in the UK; this is one of the most frequently encountered species in damper habitats.

Distribution

Widespread.

Did you know?

Unlike cleg-flies, the Twin-lobed deer-fly buzzes when it moves, so can be heard coming by its prey!