Mayfly Adult

Adult mayflies are fundamental to the sport of fly fishing.  In North America alone, over 150 species of mayflies have served as "models" for creating imitative fly patterns to tempt fish.

Adult mayflies are delicate insects with two or four triangular-shaped wings, usually having numerous veins.  The wings are held straight above the body when at rest, giving them their characteristic "sailboat" appearance.  They have well-developed eyes, small antenna and generally long forelegs.  They have 2 or 3 long tails.

Adult mayflies are unique and do not closely resemble other insects.  However, when swarming, they can be confused with caddisflies or midges.  And, the trailing legs of midges in flight can make then look like mayflies.

The mayfly is the only aquatic insect with the two-stage winged metamorphosis: the first, "subimago" (or "dun") stage is detected primarily by the "smoky" or cloudy colored wings; the final/full adult stage, "imago" (or "spinner") has clear wings.  It is during the transition at the water's surface, when the mayfly changes from larva to subimago, when the fly fisher attempts to "match the hatch" that is, to many, the essence of fly fishing.   

Mayfly adults generally live for a month or less, are nonfeeding, and mostly concerned with reproduction activities.  Swarming is common and mating is predominantly in flight.

Mayfly nymphs / Let's move on to Caddisflies