3, 4. Order Ephemeroptera (mayflies). Collect adults around lights. It is important to preserve mayflies in alcohol if possible. They are so fragile that the adults often break up easily on pins. Immatures can be collected with an aquatic net, Surber sampler or a piece of window screen between two poles. Hold the net or screen on the bottom of a stream in a riffle area. Turn over rocks and brush them to dislodge immatures that will collect in the net or screen. Specimens can also be found by examining the underside of submerged objects where they remain attached. Immatures also should be preserved in alcohol.