The lesser water boatman belongs to the family Corixidae and is the water bug we imitate with our corixa patterns. The simplest difference between the lesser and greater water boatmen, to which they are not closely related, is that the lesser water boatmen swim on their front and the greater on their back. There are 35 species in the UK with the most common species being the widespread species Corixa punctata. Corixa are frequently found in ponds and lakes and infrequently in canals or slow-flowing portions of rivers. They inhabit water bodies of varying quality with the species present often an indicator of water quality or perturbation by pollution e.g. eutrophication, acidification or salinisation.
Corixa are typically brown in colour with close set dark brown and/or yellow stripes. The body is a flattened boat shape and they have long hairy hind legs that they use like paddles, slightly shorter middle legs which are used to hang onto underwater vegetation and very short front legs that are used to scoop up food, mostly algae. They need to surface from time to time to breathe, extending this time by carrying an air bubble, under their wing cases, on their underside and around their head between their antennae. This air bubble can give them a silvery look. They are up to 14 mm in length with wings of up to 14 mm in length. During warm weather, often in the evening, the adults may take flight and migrate between water bodies. They do so by dashing towards the surface, breaking through the surface tension and taking immediate flight.
Key fly attributes are:
- Brown on top
- Light coloured under side, silvery with air bubble
- Single dark coloured leg either side of body
- Size 14 or 16 hook (depending on hook shank length, aiming for fly body length of ~10mm)
Flies to buy and try if you don’t tie:
- Light colour corixa – size 14
- Gold colour corixa – size 16
- Air bubble dry corixa – size 12
- Bead corixa
If you tie and don’t buy:
Tight Lines
Greg
Credits
- By Piet Spaans [CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5)], from Wikimedia Commons
- By Edward Saunders [Public domain], via Wikimedia Commons