If I were you I would bring some Green Drakes, Brown Drakes and some March Browns..Sulphurs also of course. There are several flies on the Beaverkill-EastBranch of the Delaware that are all lumped under the common term 'Sulphur' So bring several sizes. I've had all 4 flies on the water at once and the darn trout would switch from one to the other and during that time they would only take one of the 4...drive you crazzzzy! Whatever I think they are in the air I usually go one hook size smaller, Caddis especially. Green Drakes on the East Branch have been around June 3 thru 5 the last few years...Different sections of the river different days. Someyears they are a little late or little early. Be prepared. What a wonderful obsession we indulge ourselves in...See you all there.