Mayflies are large, flying insects that live near water. Growing up to an inch long, mayflies can live for 18 months to two years. The mayfly possesses up to three tails and long, triangular wings. Killing mayflies is possible through several different means, although fogging and using heavy insecticides are not practical. Both of the latter methods put live vegetation at risk.
Set up glue traps. Arrange glue traps on counter tops, door frames or walls. Flies land and stick -- unable to get free. Discard and replace with fresh devices when flies cover the entire surface area of the trap.
Make a bottle lure. Clean and cut off the top third of a 2-liter soda bottle. Remove the lid. Measure and cut a piece of screen to place on top of the bottle opening. Secure the screen with tape. Slice a small opening into the screen. Pour 1/2 inch of soda or syrup in the bottom two-thirds of the bottle. Turn the top third upside down and place on top of the bottom two-thirds. Mayflies will be attracted to the sugar, enter through the slit and become stuck inside. Take the lure with you on a boat or at a lake to distract and catch flies as you fish.
Use a fly swatter. Purchase a fly swatter from a local hardware store. Smack mayflies dead as they land on flat surfaces. Pack a fly swatter with you -- along with a can of fly repellent spray -- when spending time outside.
Plug in a fluorescent light trap outside or in basements or garages. Turn on the trap at night. Mayflies are attracted to the bright light and are electrocuted by the light trap cage. Turn off and unplug the trap during daytime hours, and sweep up the dead flies.