A large mayfly emergence has occurred in the last few weeks

Published 5:53 pm Friday, June 3, 2016

By Ty Torrance

You may have noticed these over grown mosquito looking insects around your house earlier this week. That is because we had a large mayfly emergence. I noticed them around the office early Tuesday morning and they were pretty much gone by Thursday. The mayfly life cycle is interesting and I wanted to share a couple of things with those of you who are not familiar with this insect.

The life cycle of mayflies consists of four stages: egg, nymph, subimago, and imago. Depending on the species, a female may produce fewer than 50 or more than 10,000 eggs. Eggs are laid in water and either settle to the bottom or adhere to some submerged object. They often hatch within two weeks but may, under certain circumstances, undergo a period of varying duration in which no growth occurs, known as diapause.

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This is a highly effective adaptation that enables the insects to avoid environmental conditions hostile to developing nymphs or to emerging winged stages.

Nymphal life may be as short as two weeks or as long as two years, although an annual cycle is most common.

When growth is complete, the nymphal skin splits down the back and a winged form, called the subimago, emerges.

The subimago flies from the surface of the water to some sheltered resting place nearby. After an interval lasting from a few minutes to several days, but usually overnight, the skin is shed for the last time, and the imago, or adult stage, emerges.

Mayflies are the only insects that molt after developing functional wings. The subimago resembles the imago in overall appearance, although it is softer and duller in color than the adult.

Most people are familiar with the adult imago stage. This is also the stage fly fishermen try to mimic with artificial lures.

Mating takes place soon after the final molt into an imago. In most species, death ensues shortly after mating and oviposition (egg deposition).

Winged existence may last only a few hours, although some males may live long enough to engage in mating flights on two successive days. Mayflies are interesting insects without a doubt, and their flights provide food for multiple species. Within a matter of days it is an all-you-can-eat buffet for fish, frogs, birds, you name it.