Recent rains have raised the level of the Beaverkill to above the average flow for the middle of August, providing a respite for the trout and trout fishers. In addition, the cool nights and generally cooler daytime temperatures have kept water temperatures favorable for the trout.
Terrestrials, such as ants, beetles, grasshoppers, crickets and inchworms, are good choices to use during this time of year, especially in water flowing under an overhanging tree, bush or log.
There may still be a few small Tricos (size #18 or smaller) hatching in the mornings, along with caddis flies and Blue Winged Olives during the day. Isonychias tend to hatch in the afternoons – these larger-sized mayflies are good swimmers, and many will crawl out on the rocks to shed their nymphal cases. A favorite Isonychia imitation is the Dun Variant in sizes #12 and #14. Toward evening, you might see the lighter-colored Sulphurs and Light Cahills hatching.
Make your casts accurate, and try not to cause disturbance by excessively mending line or plucking the fly off the water, which will put down rising fish.
In addition to the flies that may be hatching, favorite flies to use on the Beaverkill during this time of year include the Elk Hair Caddis, especially in the faster water, and the Adams in sizes #14, #16, #18.