Brachycentrus subnubilis - Grannom Caddis
The natural Grannom Caddis fly is seen on many rivers in central Southern and South West England, in Wales and Yorkshire, on the Ribble and Eden, plus in parts of Scotland. It is known in Latin as Brachycentrus subnubilis. It can be frustratingly localised, not just to individual rivers but to particular stretches of those rivers. Where it does occur, the hatches may last for anything from a few days to a couple of weeks, running from mid-morning to mid-afternoon.