I slow down my trout fishing in the month of August and I believe that the trout are slower as well. The water is low making the trout more cautious as they must elude predators. Also, the temperature of the water is high, and warmer water contains much less oxygen. Therefore the trout will be less active through the hot dog days of summer.
None the less, I can not resist some terrestrials since there is nothing like watching the trout chasing and hitting the surface fly with a mighty splash. Also, the wild Brookies of "Specs" are a sucker for a dry fly and they are my favorite trout.
Grasshoppers are somewhat ugly and somewhat clumsy often landing in the water with a splash provoking the interest of 
hungry summer trout. The strikes can be ferocious and often are. Usually grasshopper activity peaks during the hottest days of the summer which just happens to be August here in the North Carolina Mountains. Grasshoppers during August are the most readily available food source for the hungry trout, so why not use flies that mimic grasshoppers as well as other terrestrials?
Many anglers have known about grasshoppers for a long time and recognize their importance in trout fishing. Today fly patterns imitating grasshoppers are a big category of available flies on the market as can be seen at Perfect Flies web site.
Grasshopper flies can be tied using a variety of fly tying natural materials or with the advent of modern synthetic materials like foam; there are unlimited opportunities to be creative. Of course, the synthetic materials will float better and absorb less water than the natural materials, while sacrificing little of the natural appearance.
Rubber legs will provide movement to your flies and add another dimension of realism to the fly as well. These materials will allow the angler to closely match the color and size of the grasshoppers that can be found at any stream.
Here in the mountains of North Carolina and Tennessee, you seldom have the opportunity to cast more that 25 or 30 feet, so choose a 6 wt rod and a double taper floating line to deliver a nice roll cast and presentation. The tandem fly technique with an 18 to 24 inch tippet used by the National Fly Fishing Champion George Dainel, and others is recommended. To make this rig, take the monofilament tippet and attach it to the bend in the hook of your favorite grasshopper fly to which you then attach a bead head nymph. The grasshopper becomes the strike indicator. 
Don’t forget to use a single grasshopper fly any time but especially when there is any haying activity in the area. This produces a buffet for the hungry trout and they do gorge themselves at those times. Fishing near the banks on these occasions will produce some spectacular results. Pictured here is james Marsh with a large rainbow caught on the Madison River with Green Sandwich Hopper fly.