try some pink and red glo bugs in a 10 or 12, its still early but ill bet they go after them!
also, as ard mentioned, a small streamer such as a mickey finn would work as well. basic nymph patterns such as the gold ribbed hairs ear or prince nymph will be productive as also. good luck man. if you find a school of active DV, theres nothing better! make sure to pack your bug spray