Blackflies, or simuliids, are small and usually dark two-winged flies ranging in size as adults from 3mm to 7mm. They are rather seldom seen on the wing.
Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters.
Closely associated with lake and pond exits, especially those where there is a definite drop - outfalls, rather than outflows.
Adults begin to emerge when the water warms up in spring, so are active from about April to October with possible summer generations.
Larvae of the blackfly Simulium noelleri aggregate at high population densities on dams and spillways at the outlet of ponds. When displaced into the water from their point of attachment, larvae can secrete silk threads as "life-lines" which enable them to maintain a link to the substratum, and up which they can climb to regain their original position. The species overwintwers as a larva emerging in spring.
Widespread and common in England.
Thought to be common in Leicestershire and Rutland.
Leicestershire & Rutland Map
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Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015