Fly fishing hatch chart for the Yakima River.  As you peruse this please keep in mind that while it is stated to represent the Yakima, it will translate very well to any freshwater river for trout.  Be sure to take into consideration the elevation of where you are headed and whether the river or stream is a tailwater (dam controlled) or a freestone (unimpeded) as this will fudge the time lines of bugs emerging.  Questions on this, definitely call us, don't be bashful, we are here to help.