Bibio venosus


A medium-large (wing length up to 10mm), spring-flying Bibio of rather slim build with milky-white wings that have very conspicuous dark wing veins and stigma. B. venosus varies from all other Bibio species in having scarcely swollen fore tibiae and the hind tibia swollen in just the apical half.

Similar Species

B. longipes and clavipes have a similar narrow build but average much smaller, have pale wings veins, and fly later in the year. B. reticulatus also has darkened wings veins but the build is more robust and 'big-headed' and the legs more swollen.

Identification difficulty
ID guidance
  • wing length 9mm
  • hind femur swollen in apical half
  • front tibia not swollen and nearly as long as femur
  • front tibia - outer spine short (less than a third the length of the tibia)
  • humeri are yellow
  • body hair is white
  • antennal flagellum with 8 visible segments
  • dark brown/black, oval stigma
  • post. veins darkened but paler than ant. veins
Recording advice

A photo is required which shows required characters to ID this fly.


It can be found in a variety of habitats including woodland and damp scrubby areas.

When to see it

Spring and early summer. The flight period peaks in late April and May.

UK Status

B. venosus is widespread in southern Britain but rather scarce.

VC55 Status

Rare in Leicestershire and Rutland. The Martinshaw Wood record is only the second in VC55.

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Leicestershire & Rutland Map


Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map