Diptera

Female Notch-horned Cleg (Haematopus pluvialis) - Cheshire, England - June 2008

Horseflies are the largest of the blood-sucking flies, ranging in size from 8mm-25mm in length. Of the 3000+ species known worldwide, 30 occur in the British Isles.

Female Notch-horned Cleg (Haematopus pluvialis) - Cheshire, England - June 2008

Similar to many haematophagous flies, only the female horseflies feed on blood to obtain the necessary nutrients for the development of their eggs.

Male Notch-horned Cleg (Haematopus pluvialis) - Cheshire, England - August 2009

Males lack the piercing mouthparts necessary to bite and feed mainly on a diet of nectar. As a result of this many species are important pollinators of flowers. The sexes are easily differentiated by the size of their eyes: males have very large eyes which meet on the top of their head, while females have smaller eyes which are widely separated.

male Twin-lobed Deerfly (Chrysops relictus) - Long Eaton, Derbyshire

The deerflies of the genus Chrysops are very distinctive flies with their irredescent green eyes and strongly marked wings that are held in a delta shape when the fly is at rest.

male Twin-lobed Deerfly (Chrysops relictus) - Long Eaton, Derbyshire

In Britain, C. relictus is a common species in wet aluvial meadows south of a line from the Mersey and Humber rivers. It also occurs as far north as Sutherland, but is generally much scarcer.

male Twin-lobed Deerfly (Chrysops relictus) - Long Eaton, Derbyshire