Stoneflies & Weather?

Discussion in 'Fly Fishing Entomology' started by Teenage Entomologist, Feb 19, 2014.

  1. Will stonefly species such as a Golden stone or Skwala hatch in cloudy to rainy weather?
  2. Hi TaE,

    It's a couple months too early for Golden Stones like Calineuria and Hesperoperla, but I would expect the Skwala emergence to begin any time now. As to their being deterred from emerging by rainy weather, I would doubt that, as we have both in WA. ;)
    Teenage Entomologist likes this.
  3. Thanks. I was asking because I'm heading to the Pit River here in California in a week and a half, and it could be rainy. That will be good for March Browns and Baetis though.
  4. Keep in mind that stoneflies, unlike many mayflies (as March Browns and Baetis), do not hatch in midwater but crawl ashore to molt into the adult form. Skwalas, in particular, like to hang out and mate in streamside brush and grasses and are subject to being knocked into the water to become available to the fish even when the mature females are not yet laying their eggs on the water.
    Taxon and Teenage Entomologist like this.
  5. I've hatched stoneflies out of my aquarium and actually watched the molt process at night with a flashlight. It was pretty awesome. I had hatched Summer Stoneflies and Salmonflies. So Preston, your saying that the stones might of hatched during a sunny day and are waiting for another sunny day to mate? That means that you could fish stone dry flies during that rainy period between one sunny day and another?
  6. I fished Pit 3 two weeks ago and did not see any Skwalas or really any surface activity. I saw a very large rainbow rise to a snowflake.

    Bring a few stonefly dries, But plan on fishing nymphs the whole time.
    Gary Knowels likes this.
  7. I guess I don't know how you are interpreting what I said. I simply stated that all stonefly nymphs crawl ashore to molt into their adult stage (as opposed to emerging by swimming to the surface as some mayflies do). Particularly in regard to Skwala stoneflies, I've heard so many people say "Well we were going to fish dries but we didn't see any emerging" as if they expected to see stonefly nymphs emerging in open water.

    I don't believe whether the sun is out or not has much to do with stoneflies migrating ashore to molt into adults. Because of their season of emergence I suspect that, in the case of the Skwala, water temperature is a primary factor; 40-45 degrees seeming to be the range which triggers their movement. Looking under rocks close to the water's edge at these temperatures will usually reveal lots of nymphs while, a little further away from the water's edge, adults can be found sheltering in the rocks or hanging out in the grass and brush. 1-2007_0305Yaskskwalaetc0012.JPG 1-DSCF3975.JPG 2006_0330yakskwalas0006.JPG
  8. I can only go by personal experience. I've seen stonefly nymphs crawling out of rivers no matter the weather conditions. I agree with Preston that the water temp is significant as to if they decide to crawl to shore or not but it is unlikely they pay much attention to the weather conditions on shore.

    BTW: I keep reading and hearing that MB prefer to hatch during crummy weather. In all the years I've fished the valley and lower cascades streams, I've found that a MB hatch is much more likely to occur when the sun is out and the temps are warm than during rain storms.

    Either I'm doing something wrong or the "MB prefer to hatch during rain storms" is a myth.... I'm leaning heavily toward the myth option.
    Taxon and Teenage Entomologist like this.
  9. Huh, I've never heard that. BWOs, yes, but they'll also hatch in better weather. But my MB experience mirrors yours.
  10. Many stoneflies crawl out of the water at night to emerge. "Sunny" therefore not likely to be a preferred condition. :)
    Taxon likes this.
  11. Hi Arlen-

    Welcome aboard. Good point you make. Would the first initial of your last name happen to be T? :)
  12. Hi Roger, thanks for the welcome. And yes it would. :)
  13. That's great, Arlen. And now that you've broken the ice (so to speak), hope to hear a lot more from you on this forum. It's been pretty slow this winter, but should be much more active with warmer weather and the associated aquatic insect emergences just around the corner. ;)
  14. I've fished the salmon fly hatch on a certain river most springs for over thirty years. In my experience there, the nymphs crawl out on to rocks, bushes, etc., at night or early evening when there is very little light. Then they emerge from their "shell" early in the morning.

    There is nothing more exciting then fishing when trout are hitting big salmon flies on the surface! I can hardly wait.
    Taxon likes this.
  15. While my experience with salmon flies is very limited, I have observed that Skwala stoneflies tend to keep under and between the rocks as they make their way ashore and do so largely during the lower light periods of the late afternoon and evening; a sensible choice to avoid avian predation. Newly returned Redwinged Blackbirds seem to be particularly interested in seeking them out.
    Taxon likes this.
  16. Preston, most years if I time my trip right the bushes along the river are full of salmon flies. Interesting, I've never seen birds go after them in the bushes though they would be easy targets. You do see swallows grabbing them out of the air when the females are flying upstream depositing their eggs

    At the peak of the hatch on a warm evening - right at dusk- the females will swarm and thousands of salmon flies will fill the sky. It is quite a sight.
  17. Salmonflies also make quite a helicopter noise when they are flying. One of the least graceful flight attempts I've ever seen.
  18. Arlen!!! You're here! My favorite bug guy and macro photographer!

    Posting your photos here is very, very easy. Your shots have always amazed me as to how you get the bugs to model for you :) .

    Seems to me I recently read a chapter from your book in FFM...
  19. Hi, Gene. Good to see you posting here, and I really appreciate the kind words. It looks like there are is a lot of interest here in the bugs of fly fishing; and some very knowledgeable folks like Roger to shed light on the subjects (to put it in photographic terms :)).
  20. Yup, 27K members from all over the world means this place has a huge knowledge base. Now that you're posting it has increased that much more.

    Lot's of neat forums here. The Fly Tying Forum is also a wealth of information... the SBS section is great.

    Hope you continue to contribute.

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