Mayfly nymphs are categorized as digging, clinging or swimming nymphs. These are usually found in different water types and environments. The nymphs are active all year a round and are of interest for the angler from spring to autumn.
Digging nymphs are often found in lakes and slow moving parts of streams, creeks and rivers. They usually prefer a softer bottom or sand. Some of the largest mayflies have digging nymphs, such as the Green Drake.
Swimming nymphs are, just as the name says, good swimmers. You will find them in both still and moving water. An example is the Claret Dun.
The body builders among mayfly nymphs are the clinging nymphs. Compact, with a low profile and strong legs, they are able to move around on rocks even in the roughest of streams, creeks and rivers. There bodies are shorter then both the ones of digging and swimming nymphs. An example is the Yellow May Dun.
As mayfly nymphs spend most of their time close to the bottom and only moves longer distances by swimming or drifting downstream when they seek food, accidently loose their grip or when they are about to hatch, it is a vise choice to fish an imitation close to the bottom when you can’t see any mayflies hatch.