If I had only known they were new-I'll see if any of the bodies are half decent to photograph (or try my light tonight but I think the live ones are all gone)

Edit: I just read that this species comes out and breeds and all die at once in one night-guess it's the only chance I'll get this year. (Unless I get lucky enough to see another "hatching")It says it happens for 3 weeks in August.

Great photos, Jo Ann. It's nice to see these old friends from the Lehigh. While it's true that those that emerge on a given evening will mate, lay eggs, and die that evening, the emergence period usually lasts for a few weeks in any section of a stream or river. The emergence may be heavier or lighter from one day to the next, but you should see more. (Look around lights near some of the slower, siltier sections of the Lehigh if you want to improve your chances. The females seem to have a greater attraction to lights than the males, but you should see some males if you are close to the river.)

Due to their atrophied legs, the females that get drawn away from the water will be found flopping helplessly on the ground. The males have functional forelegs for grasping the females during mating and will undergo the second molt to become an imago. The molted males will then have two tails, though they are often seen with the subimago shuck still clinging to their tails.

yes that's what I meant0body length

please edit the size box to make it comprehensible; i could do it myself but can't assume responsibility since i didn't measure the insect and i'm still not sure how long was the body

They were all that color and the females had eggs-and then they all died..I still have bodies all over my porch

I searched for more pictures of the species and the bodies are more of a cream color, and the wings clearer, but in some mayflies the females do reproduce in the subimago stage, and never molt to become an imago. Perhaps this is one of those.

Did you look at this?
http://www.wiflyfisher.com/ephoron-leukon-mayfly-hatch.asp

The bodies are a different color than your image, and the wings seem a little clearer on some. The forelegs are also fully developed. The clear wings, cream body, and fully developed legs indicate males. The body on your image still has a lot of pubescence, and the legs are vestigial. Although the bluish tint is possibly the hairs catching blue from that background.

I found this article about Ephoron that states "Unique among mayflies, the females don't molt". They remain in the "dun" stage which is the subimago. So if this is a female it is a reproductive subimago.

http://www.troutnut.com/hatch/820/Mayfly-Ephoron-White-Flies

Here is another picture in the guide of E. album where someone else has commented that the females in this genus do not complete a final molt but remain in the subimago stage and have vestigial legs.

http://bugguide.net/node/view/208588

So do we refer to them as adults ? Not really right. I know little to nothing about mayflies and their kin. I was just amazed me how many of them were flooding my porch which is kind of far from open water (in my opinion to attract so many)

As for the legs-maybe that's why they didn't walk around-just sort of laid on the porch flapping-I thought it was because the porch was wet and for some reason they were sticking to it. Then I read the description on the E.alburn-and it was very similar. The species I photographed seemed quite a bit larger (or my hands are smaller).

The bluish tint IS definitely the background I used. Sorry about that.

The subimago is usually an adult that is not quite fully developed. Normally their reproductive organs are not fully functional until the imago stage. Its a strange concept to think of in insects because adults are usually the final reproductive stage and immatures never have wings. Its interesting that the males do have a subimago and an imago, but the females don't. The females have even lost their legs because they don't need them, they just mate and die!

I'm sure the size difference between the species is just that E. album is a smaller member of the genus.

Thanks for highlighting a few of the differences between mayflies and other adult winged insects, Natalie. As probably the most primitive extant order of winged insects, modern mayflies offer a fascinating window into the process of evolution. However, defining terms like "adult" or "mature" is not nearly as straightforward with regard to mayflies as it is with most other winged insect orders.

Although it seems generally accepted that most male subimago mayflies are not fully functional from a reproductive standpoint, that is less true of female subimago mayflies. Edmunds and McCafferty (1988) speculated that all female mayflies may be capable ("physiologically, if not behaviorally") of reproducing as subimagos. They cite examples of successful fertilization of female subimagos by male imagos (both naturally and artifically) in lineages that retain the female molt to the imago stage. There is also at least one example of a parthenogenetic species (Eurylophella oviruptis, Funk et al., 2008) in which the females can reproduce/oviposit by abdominal bursting as subimagos even though the imago is still retained.

The molt to the imago demonstrates other interesting specializations among some mayflies. In some (such as Ephoron), the female imago is lost (no apolysis). In others (a couple of leptophlebiid species), the imago is retained but the molt is lost, producing a "pharate" adult (apolysis, but no ecdysis). In still others (some oligoneuriids), exuviation is partial, with the subimaginal covering being retained on the wings. And a few species (Old World palingeniids) retain much of the appearance of the subimago after the molt to the imago.

As a side note, yes, E. leukon is usually somewhat larger than E. album.

Thanks for all the information :)

I was also told that the legs on Mayflies are more for propping themselves up and grasping during mating then for actual movement. So even adults with "fully developed" legs often don't move very well.

Although most mayflies with functional legs can walk reasonably well, they often prefer to fly when disturbed. A number of people have commented on how docile mayfly subimagos seem, but I suspect that is most often related either to being somewhat teneral or to the need to conserve energy for the molt and mating to come.

Some mayflies, like Ephoron females, cannot walk at all. The subimago males of Ephoron can grasp well enough with their forelegs to accomplish the molt to the imago, and they still use their elongated imago forelegs to grasp the females during aerial mating in typical mayfly fashion. Peters and Peters (1986) report that males of Dolania americana, another species that lacks a female molt into the imago, usually leave the tarsi and claws of their middle and hind legs behind when they molt into imagos. Leg reductions, like hind wing reductions, seem to have evolved independently in several families.

Thanks! I'm learning so much about Mayflies! Awesome!!