Twin-lobed Deer-fly

Chrysops relictus

  1. Wildlife
  2. Invertebrates
  3. Flies
  4. Twin-lobed Deer-fly


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, usually cows and ponies, but will happily drink the blood of humans too. The males lack these mouthparts, and 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 onto 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

When seen up-close, the Twin-lobed Deer-fly is one of the most beautiful horse-flies, 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.

Where to find it



When to find it

  • May
  • June
  • July
  • August
  • September

How can people help

Horse-flies are considered pests due to the bites which they can inflict, causing blood loss and diseases in some species. However, they are still a link in the food chain and are predated upon by birds and other animals. The Wildlife Trusts recognise the importance of healthy habitats to support all kinds of species throughout the food chain, so look after many nature reserves for the benefit of wildlife. You can help too: volunteer for your local Wildlife Trust and you could be involved in everything from coppicing to craft-making, to stockwatching to surveying.

Species information

Common name
Twin-lobed Deer-fly
Latin name
Chrysops relictus
Body length: 1cm
Conservation status