Also known as the "Two Feather Fly" http://www.fish4flies.com/Dry/Winged/Two_Feather_Fly And tying instructions http://flyanglersonline.com/flytying/fotw2/040703fotw.php
I have not fished them yet as not the right time of year but would imagine they would get battered pretty easy but due to them being simple to tie you can rattle off a good box full.