Let the fly drift down with the current. Look for cover where a hopper might have been, make your cast there. The winged ant found in the west in May or June is a size 10 or 12. Land the fly gently, in front of the trout's nose, and barely inch it forward. A 10-feet leader, and 6X tippet are necessary to sucessfully fish ant patterns.
Midges appear throughout the year in rivers.
Some as large as a size 14, but more commonly size 20 - 28. Leaders need to be at least 10 feet long, and tippets should be 6X. Presentation should be directly in front of the trout's nose, do not move the fly, the trout should just suck it in. In moving current, let the fly drift downstream. In lakes, you will get one cast to one fish. The cast must be presented to a actively feeding fish.