Stoneflies & Weather?

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

  1. Teenage Entomologist

    Teenage Entomologist Gotta love the pteronarcys.

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    Will stonefly species such as a Golden stone or Skwala hatch in cloudy to rainy weather?
     
  2. Taxon

    Taxon Moderator Staff Member

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    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. ;)
     
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  3. Teenage Entomologist

    Teenage Entomologist Gotta love the pteronarcys.

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    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. Preston

    Preston Active Member

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    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.
     
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  5. Teenage Entomologist

    Teenage Entomologist Gotta love the pteronarcys.

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    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. Travis Bille

    Travis Bille Active Member

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    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.
     
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  7. Preston

    Preston Active Member

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    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. GAT

    GAT Dumbfounded

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    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.
     
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  9. tkww

    tkww Member

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    Huh, I've never heard that. BWOs, yes, but they'll also hatch in better weather. But my MB experience mirrors yours.
     
  10. Arlen

    Arlen New Member

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    Many stoneflies crawl out of the water at night to emerge. "Sunny" therefore not likely to be a preferred condition. :)
     
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  11. Taxon

    Taxon Moderator Staff Member

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    Hi Arlen-

    Welcome aboard. Good point you make. Would the first initial of your last name happen to be T? :)
     
  12. Arlen

    Arlen New Member

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    Hi Roger, thanks for the welcome. And yes it would. :)
     
  13. Taxon

    Taxon Moderator Staff Member

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    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. Steve Call

    Steve Call Active Member

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    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.
     
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  15. Preston

    Preston Active Member

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    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.
     
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