These are aquatic insects in their immature stages, as the larva (called naiads) live at the bottom of lakes and streams, feeding on small animals, vegetation, or organic debris. They also become a major food source for other aquatic organisms such as fish. In warm weather the adults emerge in large numbers, and they are attracted to lights and may gather on structures in enormous numbers. Once the insect acquires wings it may fly a short distance, land on a surface, and molt once more to the adult stage, leaving the old exoskeleton stuck to the surface. It is possible that these disintegrating skins can become a cause of inhaled allergenic reactions as they blow in the wind. Adults generally live 1 to 3 days.
There is no need to control these insects, other than exclusion from structures by maintaining windows and doors screened or closed. Reducing exterior lighting, or changing white lights to yellow bulbs, will reduce the attraction of the insects to the structure.