A pattern for fishing the shallow margins and weedbeds, often best fished along a quiet bank in early evening. The corixa or lesser water boatman is typically 6-12 mm in size, so patterns are typically tied on a size 12-14 hook. As they don’t have gills corixa make repeated journeys to the surface for oxygen that is then held on the underside of their body, appearing like a tiny air bubble. Not surprising, therefore, that they live in relatively shallow water. The body on this pattern is tied with Madeira metallic thread, which gives it a rather nice transparency, simulating the air bubble that these insects use to breath underwater. Alfred Courtney-Williams  gives an early pattern for corixa, attributing it to T.J. Hanna. That ‘Water Bug’ pattern is decidedly a more complex pattern than we might routinely use today, involving stripped hackle stems, Plymouth Rock hackle and speckled hen wing feathers.
However, this particular pattern has its roots in a pattern attributed to Dr Howard Bell of Blagdon by John Veniard  who cites an article in the Fishing Gazette of April 1958 where this and several other of Bell’s flies are described by Col. Esmond Drury. Dr Bell’s pattern uses a body of white or cream floss ribbed with brown tying thread and a wing case of woodcock wing fibres using a white or cream throat hackle to imitate the legs. Given Dr Bell’s reputation for developing a meticulous, scientific approach to the study of his catch, regularly examining the trout he caught for evidence of what they had been eating, it is not surprising that he came up with this simple and rather close imitation of corixa.
- Alfred Courtney-Williams, A dictionary of trout flies and of flies for sea-trout and grayling (London: A&C Black, 5th ed, 1973)
- John Veniard, Reservoir and Lake Flies (London: A&C Black, 1970)