They are also attracted to lights. Eggs are deposited while flying low over the water, or by dipping the abdomen on the water surface or some even submerge themselves and lay eggs underwater. Adult females lay eggs into water and often die on the water surface. The number of molts varies depending on the species, temperature and water conditions. Immature stages then swim to the water surface or crawl onto rocks or plants.
Mayflies are the only group of insects that molt after they have wings.
In all other orders winged forms are as only found on adult forms, the last stage of development. A typical life cycle will last one year. Most of the species in Texas prefer flowing or highly oxygenated water situations. A few species develop in lakes or ponds and their distribution in water is usually limited by oxygen content of the water. They are medically harmless.