Saturday, August 19, 2017 Exit Glacier and Mayflies

Seward, Alaska

It was such a nice day, sandwiched between seemingly endless rain, that I decided to be a real tourist and visit Exit Glacier too.

The parking lot was full to overflowing, but remarkably there were periods when I had the whole trail to myself. During one of these amazing gaps in visitors, I spied a large, winged insect on the paved path. I crouched down and took several photos.

It was so striking with its banded abdomen and almost clear wings. Most striking were the three tails, not ovipositors. This must be a Mayfly!

Fortunately, it flew off before a herd of boots squished it.

Not too much farther along, I found another one and again took photos. This one held a beautiful green ball of eggs under its curved abdomen. Wow! I’ve never seen anything like that!

The Mayflies seemed so out of place in such a wild and young ecosystem. Exit Creek was raging from the recent rains and snowmelt. Feeder creeks were erratic, and I didn’t notice many ponds or other suitable Mayfly habitat. To randomly find two adult Mayflies at Exit Glacier was really amazing.

I tried to identify the species when I returned home. There are about 50 species in Alaska, and I was unsuccessful in identifying this one. Two of the descriptions, however, mentioned the ball of eggs. 

One said the Mayfly scatter-bombs her eggs by dropping the entire ball over the water. The other said she dips down repeatedly and drops just a few at a time.

There were many websites for fly fishers. Mayflies are such an important food source for fish that every successful fly fisher has imitation nymph and adult Mayflies in his tackle box, knows their life cycle, and notices the timing of the hatch when large numbers emerge at once and fish enjoy a feeding frenzy.

It was so interesting to learn that when the immature aquatic stage called the nymph or naiad emerges, it molts into a fully winged adult stage called the subimago, and then molts again into the final adult stage. This is a unique characteristic among insect orders.

The long tails and wings that are held upright instead of flat over the abdomen are primitive ancestral traits of the first flying insects. Primitive or no, this is a very complex insect!

Mayflies are indicators of a clean, unpolluted environment. Yay!

Mayflies are in the Order Ephemeroptera, which refers to “ephemeral” as in the adults don’t live very long. I felt very fortunate to notice these beauties in time!

If anyone knows more about this particular species, please let me know.

Happy Trails!

Carol Griswold

Seward Sporadic Bird Report Reporter