While walking the river last week searching for rising fish, I stopped by an eddy to see what insects I might find. To my surprise, I found many fall PMDs and a few other insects as well. It reminded me of a few posts I’ve written about PMDs over the years. And it also made me think how much I enjoy mayflies. I thought I’d provide a refresher for you in today’s post.

PMDs of Water | www.johnkreft.com

I’ve taken lots of pictures of PMDs over the years and thought I’d start today’s post with recent images I captured last week of the mayflies I found.

Upgrading cameras and lenses as well as learning new techniques has really improved my photographic skills.

This Rusty Spinner is a perfect example. It’s from the first year of RiverKeeper Flies.

Rusty Spinner | www.johnkreft.com

A little different than the quality of pictures I capture these days.

Fall PMD - Metolius River | www.johnkreft.com

Or this spinner. It’s not a PMD spinner, which reminds me I need to find one on the water and update my photo!

Spinner on Water - After | www.johnkreft.com

I am mesmerized by these mayflies, both their colors as well as colors found in the water and streambed.

Lots of Mayflies Floating in Eddy | www.johnkreft.com

We saw our first PMDs in May and they continued to hatch throughout the season. But they are almost done. It won’t be long now and they will only be a memory.

PMDs, otherwise known as Pale Morning Duns, are an important hatch for fish and fly fishers. Generally, you’ll find these flies in sizes 16 -18. Normally, they hatch in the afternoon between 1 and 3 pm on my local river. You’ll find them floating down the river with their wings upright.

PMD Floating on Surface | www.johnkreft.com

Most of the time, PMDs have a pale yellow body and smokey gray (or dun color) wing. But their body colors vary and include shades of pale green, yellowish-tan, or a light reddish-brown. Look at the bug carefully. The underside of the insect is what the fish sees and the color is usually lighter than on top.

PMD - Reddish-brown Body | www.johnkreft.com

I found a variety of colors and shades in the eddy (No, not all of these are PMDs.) I like that several are hitching a ride on the leaf

Most of these mayflies have their wings caught in the film.

Mayfly Wings Caught in Surface Film | www.johnkreft.com

And look closely at the partially submerged mayfly in this image.

Partially Submerged Mayfly | www.johnkreft.com

Mayflies in general spend much of their life as a nymph, rummaging around the rocky stream bed. When it’s time to hatch, the nymphal shuck breaks open and an adult mayfly crawls out and becomes a dun. Hatching may occur underwater or in the surface film. The PMD breaks through the surface film and waits for both wings to dry as the fly floats downstream in the current. Now the mayfly flutters its wings and takes flight. Sometimes it lands on the water again, floats some more then flies away to nearby vegetation and wait to become sexually mature.

I’ve shared this video before. It isn’t a PMD, but I show it here to highlight how mayflies break our of their nymphal shucks and take flight.

A good number of mayflies don’t make it out of the nymphal shuck. We call these cripples.

Here is a PMD found in a back-eddy that was stuck in its nymphal shuck.

PMD Spinner | www.johnkreft.com

Look closely and you’ll see the empty nymphal shuck stuck to the back of the natural. It was unable to fully climb out. It’s a perfect example of why I use a Sparkle Dun to imitate this activity.

In the last phase of mayfly life, the dun sheds the skin as the thorax splits open and out crawls another insect with clear wings which is called a spinner. The body color of the PMD spinners range from tan to rust, hence the name “Rusty Spinner”.

Females fly into swarms of males to mate. Watch for birds flying above the river. That’s a tell-tale sign spinner activity is about to begin. After mating, the males drop into the water and are available to fish. You probably won’t see them, only the occasional sip of a trout and you’ll ask “I wonder what it took”? That’s the time to pull out a Rusty Spinner.

Another interesting fact is how to distinguish a female from a male.

Check out the eyes in this older image. Males have large, bright orange or rust colored eyes whereas females are pale. Look back at some of the images above and you’ll see the difference. Find a back eddy during a PMD hatch like I did and pick up a few real bugs. You’ll be amazed. At times, I think the fish key on them. Such a small detail…

PMD - Male|www.johnkreft.com

Here are my favorite dry flies I use to imitate PMDs.

Other popular flies to imitate the various stages of a PMD include:

For more flies to imitate PMDs, check out the Mayfly Fly Patterns page.

Remarkably, in spite of all of these mayflies floating on the water on that day, no fish were rising to them!

Lastly, I’ve included a couple more posts from the Archives you might enjoy:

If you’d like to learn more about entomology, BugWater: A fly fisher’s look through the seasons at bugs in their aquatic habitat and the fish that eat them by Arlen Thomason is a terrific book I highly recommend about the most common bugs you will find on your local river.

Enjoy…go fish!

(John Kreft is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.)

Similar Posts

One Comment

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.