It’s Salmonfly Time!

by Judy Lehmberg, BioPics Photography, www.vernelehmberg.com (25% off sale of all photos for a limited time if you use the code “4000likes” without the quotation marks)

Adult Female California Salmonfly
Adult Female California Salmonfly

This particular salmonfly, or stonefly, is Pteronarcys californica, one of the largest aquatic insects around. It is exciting to fly fishers when they hatch because it means every big trout in the stream is going to be up looking for them.

Adult Female California Salmonfly
Adult Female California Salmonfly

The California Stonefly females can get up to three inches long. The males are smaller, but it takes less room to carry sperm than it does eggs. The females lay eggs by repeatedly dabbing their abdomen in fast moving water. Once the eggs hatch they become a nymph that can live in the water three or four years.

Salmonfly Nymph
Salmonfly Nymph

When the nymphs are ready to transform into adults they crawl to the shoreline and split open their exoskeleton. The newly hatched adult sits for a few hours drying its wings and then walks or flies off in search of a mate. Once they mate the female returns to the stream to lay eggs and the whole process starts over.

  California Salmonfly Emerging From Its Nymphal Exoskeleton

California Salmonfly Emerging From Its Nymphal Exoskeleton

If you are in Yellowstone go to La Hardy Rapids on the Yellowstone River. Look at the base of the trees near the river and you will see hundreds of discarded salmonfly exoskeletons. You will also see salmonflies flying around, especially in the late afternoon. If one lands on you let it walk around for a while. They don’t bite but they do kind of tickle. Walk downstream a little way and you may be lucky enough to see a cutthroat trout catching their favorite meal, a California stonefly.

Yellowstone Cutthroat Trout Grabbing a California Salmonfly Nymph
Yellowstone Cutthroat Trout Grabbing a California Salmonfly Nymph

8 thoughts on “It’s Salmonfly Time!

  1. Sitting in Canyon, waiting for my clothes to wash and for your photos to upload with the slow internet, and thinking how lucky we are to have you sharing these fascinating stories with us. Thank you Judy.

    1. Thank you Deby. I like it, it gives the biology teacher in me something to do, but I don’t have to stick to a syllabus. That makes it fun!

  2. Found one on the Madison two weeks ago before the guide or my fisherman hubbie. 🙂

  3. Interesting article. Are these in Yellowstone most of the summer Judy, or just for a short time? We are hoping to do some fishing while we’re there next year so I was just wondering.

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