On the day I just described, for example, I figured the adult caddisflies were laying eggs. Most egg-laying caddis females either crawl underwater on a protruding log or rock, or dive-bomb in and swim to the bottom. To breathe, the insect carries an air bubble around her body. Once on the bottom, she deposits her eggs and then releases her hold and pops to the surface, buoyed by the air bubble. At the surface the bubble bursts, and the female immediately flies off. Some trout, especially smaller ones, chase the rapidly ascending females and grab at them. Such swift pursuit often carries the fish in an arcing jump well above the water.