Tricos usually emerge (very) early in the morning from July to September. If you have ever fished this hatch you know how challenging and fun it can be. These guys can be just maddeningly difficult, but they bring up lots of trout. Tippet down to 7X and a precise drag free drift are a must. I like to throw my spinners about 10-12 inches off the bend of a big bushy dry fly for better visibility. An Ausable Bomber works great for this. For a female spinner, use light olive thread.
More trico patterns: Double trico spinner, cdc trico, sunk trico spinner
Check out Tricos- Four Patterns to Fish the White Winged Curse