Remember that Isonychia are a fast water bug, so look for hatching activity there. Nymphing is still mostly smaller flies in the #18-22 range, exceptions being Stoneflies #6-12 (brown, golden/yellow), Isonychia #10-14, and Caddis Pupa & Larva #14-18.
Ants, Beetles and Hoppers have been working well in the afternoons, when hatch activity is low. We are also starting to see some decent numbers of flying ants #22-24 in the afternoons on the more humid days.
Summertime bugs are smaller on average, so when nymphing make sure to downsize your flies. #18-22 nymphs are often the key to success, with fly size more important then the exact pattern (although I prefer either a little flash or a fluorescent hot spot in my small nymphs). Some days small flies are the difference between struggling to hook trout versus catching a bunch. The two main exceptions would be Isonychia nymphs #10-14, and big Stonefly nymphs #6-12. Iso's are typically active later in the day, say late afternoon through dusk. The evening Cahills are also bigger at #12-14, and can be nicely imitated with either a Fox Squirrel or Hare's Ear nymphs. The big Stonefly nymphs emerge by crawling out onto rocks overnight and in the early mornings, making early/mid mornings prime to fish their large imitations for larger trout. If you do have a big fly on, make sure you also have another pattern in your rig no bigger than a #18, it's more in line with what they are seeing this time of year.
Top Dry Flies: Blue Wing Olives #22-26, Needhami #22-26 (mornings), Summer/Winter Caddis #18-24 (mornings in permanent C&R/TMA), Sulfurs #18, (Riverton only), Cream Cahills/Light Cahills #12-14, Isonychia #10-14, Beetles & Ants #14-18, Summer Dark Caddis #16-22, Tan Wing/Olive body Caddis #16-18, and an all Tan Caddis #16-18 . The best dry fly activity has generally been in the riffles and the upper end of pools including Pipeline, Roberts, Whittemore, People's Forest, Church Pool, Greenwoods and the Boneyard. Try also blind-fishing with attractors such as Mini Chernobyls #12-16, Stimulators #10-16 & Hippy Stompers #16-18.
Nymphing has typically been the most productive method from late morning through early evening (when the insect activity is sparsest) and is accounting for the lion's share of truly big fish, using patterns like Caddis Pupa #14-18 (tan, olive-green- Caddis pupa are especially active in the mornings), Antoine's Perdigons #16 (various colors), Attractor nymphs #14-18 (Frenchies #14-18, Egan's Red Dart #14-16, Rainbow Warrior #16-18, etc.), big Stoneflies #8-12 & Pat's Rubber Legs #8-10 (especially in the mornings), Quasimodo Pheasant Tails #14-22, BWO nymphs #16-20, Isonychia #10-14 (mid afternoon thru eves), Fox Squirrel Nymphs #12-16, and Zebra Midges #16-22.