Others include ants, beetles, spiders, bumblebees and fireflies, also called lightening bugs. For fly photos check the Fly of the Week Archives. Keep in mind that trout all fish are opportunists. They will eat whatever is available. In most regions hatches do not occur every day throughout the year.
Fish have to conserve energy.
That means they can't spend their days and nights swimming aimlessly looking for food. By instinct they know where are the most likely places for food to be. It may be a nymphal stage of some insect or it might be a spider who missed his footing. Learn to look at more than just the surface of the water. Check that 'magic inch' of the surface.