Oliver Edwards hydropsyche and rhyacophila patterns are well renowned and I have had reasonable success when using them. The materials to tie the hydropsyche are easy to get hold off, the specified yarn for the rhyacophila is a little harder to track down. If you're not a fussy person you can use any wool or yarn of the right colour to tie them - being mindful that natural fibers darken when wet; I'm more of a fussier tier, I would rather use the specified materials.
A little bit of effort, has seen me source a large quantity of sparkle yarn that is probably equal to the original Oliver Edwards product. I have a small amount of the 1a rhyacophila sparkle and the new stuff is comparable to the original in its make up and the colour seems spot on. I also have a small amount of yarn in another colour; I have used this to make a variation on the hydropsyche using yarn for the body instead of nymph skin.
|Oliver Edwards' Rhyacophila larvae|
|Oliver Edwards' Hydropsyche larvae|
|The two combined|