Insect Order Ephemeroptera

Insect Order Ephemeroptera - Mayflies
Common Names: Mayflies, Mays, Upwings, Duns, Spinners, Dippers, Fish Flies
Ephemeroptera, Greek Ephemeros - short-lived, pteron - wing, referring to the short life span of adults. As winged adults, they survive only a few hours or at most a few days. They eat nothing, nor do they crawl or walk. They only fly and mate within dancing swarms, usually in late afternoon or evening. Swarms, consisting of hundreds or thousands, emerge from the water after synchronously appearing along and inland of the shoreline... continued below

Live adult mayflies photographed at North Carolina and Illinois. Please select a thumbnail for larger image.


	Adult Mayfly - Hexagenia sp.
	"Mayflies constitute one of the most important groups of bottom-dwelling animals in streams and rivers throughout the world. They are also found in ponds and shallow lake areas. While the larvae (or nymphs) of mayflies live in water, the adults (and subimagos) are delicate flying forms noted for their often ephemeral lives. Mayflies are routinely used for monitoring water quality because their presence and diversity can be valuable indicators of the health of their aquatic environment. Mayflies are a vital link in the food web of freshwater ecosystems, making energy stored in algae and other aquatic plants available to higher consumers (other invertebrates, fish, birds, etc.). Any fly fisher can expound on the value of mayflies as food for many gamefish and more specifically as models for fashioning tied flies." - from Mayflies of North America

Description: Soft bodies with short setaceous (bristle-like) antennae and vestigial mouthparts; wings held vertically at rest, hind pair much reduced; intercalary veins and many crossveins present; abdomen with long cerci, and with or without a medial caudal filament; larvae (nymphs) aquatic, campodeiform (elongated and flattened) with tracheal gills of varied form; true adult preceded by a subimago (winged instar).

Life Cycle: Mating normally occurs the same day adulthood is achieved. Females release as many as 8,000 fertile, oval eggs over the water, often scattering them or, in some species, in mass in a suitable place. After eggs are laid, females fall to the water and float, often drifting onto beaches in nuisance piles or windrows. Others are strongly attracted to and congregate under night lights.

Eggs laid on the water surface gradually sink to the bottom and, after a few days or several months, hatch into tiny aquatic nymphs well adapted for living at the bottom of quiet bodies of water or rapidly flowing streams. Some species burrow into the lake sediment to feed on algae, diatoms, aquatic vegetation, other aquatic insects, etc. When mature, nymphs swim to the surface or climb up plant stems or rocks where they break the nymphal skin, wait briefly for the wings to dry, and fly off. (This subimago period lasts a few minutes to 48 hours, depending on the species.) Subimagos are dull in appearance while true adults are shiny with longer tails and legs.

Anglers go to great lengths to identify hatch periods, and there are hundreds of different types of both wet and dry artificial flies for dozens of different species, water conditions, adults, nymphs, you name it. The flies have fanciful names such as Blue Wing Olive Hackle Stacker Sparkle Dun, and Green Drake Loop Wing Paradun.

Parachute Cream Puff
"This fly is very popular for imitating Pale Morning Dun Mayflies."

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