Gilly Bate, southern chalk stream guide and Fly Odyssey UK Director offers her go to flies for the Southern English chalkstream fishing during the prolific mayfly period of May.
In the first few days of the mayfly the trout can be a little nervous of the mayfly but they are quite keen to take emerger patterns such as Paul Procter mayfly emerger. Once they have established feeding on mayfly first choice of fly is the legendary Grey Wulff. Size can vary with size but usually size 10 is best. An alternative is the Green Drake which also works very well. The classic French Partridge is a terrific mayfly pattern and seems to work throughout the different stages but it is supposed to represent a spinner or spent pattern. As the trout become sated on the mayfly they can become quite discerning about which pattern they will feed on. X factor Pink Lady and Procter Mayfly Spinner can be a good choice towards the end of the mayfly period.
Mayfly hatches are sporadic throughout the day with the main hatch from approximately 4 pm onwards. On overcast/cold/wet days Iron blues can be present. size 16. Trout will often ignore mayfly and choose iron blues instead. Other Olives present during May are Large dark Olives, medium and small so have a selection of flies to cover these patterns: CDC F Fly olive, Greenwells, Parachute Adams – size 12 – 16. Lunn’s Particular size 14. On tricky days they could be feeding on very small black gnats – size 18 CDC F flies in black. Hackled Black Gnats and Parachute Black Gnats – size 14 – 18.
Sedges may appear at any time through the day although they normally appear late afternoon onwards. Small cream sedges CDC elk size 16 and the occasional red sedge Walkers red sedge size 12.
Remember to match you leader size to the fly. Big flies require thicker leader to turn them over and present the fly. 6 lb tapered leaders are best. If you need to tie on a smaller fly then add around 15 inches of thinner (size 3.5 lb) fluorocarbon to the end of the leader or change your leader to a smaller diameter (4lb breaking strain). Good luck on the river this month and hope you all enjoy the classic dryfly fishing that the mayfly hatch is so well known for.