Whats the difference between a skwala and golden stone?

Discussion in 'Fly Fishing Entomology' started by golfman65, Apr 9, 2009.

  1. Title pretty much says it all..

    I've found lots of goldens up north on a river I fish and have asked around but no seems to think skwalas are up there..so wondered what the diff. is?

    Here's a shot of a golden I took last Friday..

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  2. Traditionally here are some factors that separate

    1. Skwalas are usually first of the stones to come off

    2. Color, duh!

    3. Size variations. Goldens can be big to small...up and down!
  3. I thought the following was a great contribution from a recent thread.
  4. I'll add to this.

    1. Skwala's do typically come off first, agreed.

    2. Skawal's range from tan to dark greyish to olive, with a lighter underbelly than back. Goldenstones typically are a yellowish/orangeish hue.

    3. Both bugs vary in size substantially among the species. Goldens are typically bigger, but from my experience, not much. The biggest indicator for me, other than the time of year, which is about 1.5 month difference where i'm usually fishing, is the color, goldens are really that, golden colored.
  5. I found both under rocks on the Yak this past Tuesday. These ones happened to be nearly identical in size (about a half inch long head to butt, not including the tails), but the underbelly of the Skwalas were very much olive whereas the Goldens were very yellow/gold. Interestingly, both had visible wings, but were still in hiding.
    Saw no adults all day.
  6. Skwala stoneflies hatch most commonly from mid-February through mid-April and, at least locally, tend to be dark, from a sooty black through a dark olive. They sometimes exhibit yellow markings on the underside of the thorax and abdomen. Golden stones rarely hatch before May and tend to range in color from brown to yellow. Although there isn't a great deal of difference in size, goldens do tend to be a bit larger than Skwalas. I tie most of my Skwalas on 2x-long size 8 dry fly hooks but would go up to a 6 for goldens. From the one picture that was clear enough, I'd say what you were looking at were Skwalas.
  7. I'm not so sure your picture is not of a Skwala...check out this picture that is of an adult Skwala. Notice the yellowish line in the center of the pronotum and mesonotum. While this definately isn't a characteristic used to distinguish between the species, I believe goldens have a more vermiculated pro and mesontum. However, one characteristic that is used to distinguish between the subfamily Perlodinae (which the genus Skwala is in), and the subfamily Isoperlinae (which the genus Hesperoperla and Calineuria are in (and is the genuses of the Golden Stones)) is the presence of supplementary veins in the R1 - Rs space. The Skwala in the picture I have attached have these supplemental veins present. Unfortunately, the R1-Rs space in the picture from the original poster is in the shade and I cannot tell if there are supplementary veins. Maybe if there was another picture....?

    The colors on Skwala's can vary so much that they could easily be confused with Golden stones, while the Golden stones colors do not vary quite as much..most are golden/golden orange/golden tan. Skwalas on the other hand can range from almost black, to olive to light tan. Also, the lower end of the size range of Goldens definately overlaps with the larger end of the size range of Skwalas. Pretty much just repeating here what Jergens said. I would say the largest Goldens are a size 6 though, so they are not that much larger than the largest Skwala.

    Anyways, probably too much info....Any thoughts?


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  8. The pics in the OP look Skwalas to me. Like others have said, the Goldens I've seen really are golden/tannish. The dark color of the bug and the yellow around the thorax and leg joints in the OP is consistent with Skwala IMO. I actually tie my Skwala patterns with yellow/black barred rubber legs to mimick the look seen in the OP's pic.

    Of course, confusion between Skwalas and Goldens isn't anything new. Anybody who's read Steve Probasco's Yakima River Journal knows about the great March Golden Stone hatch on the Yak.;)
  9. :thumb::)
  10. James-

    Genera Calineuria and Hesperoperla are in Subfamily Acroneuriinae of Family Perlidae (Common Stoneflies).

    Genus Skwala is in Subfamily Perlodinae of Family Perlodidae (Patterned Stoneflies).

    This can be visualized somewhat easier on Stonefly Taxonomic Structure.
  11. :ray1: Thanks, Roger- I was just going to say that! :D
  12. You're welcome, Itchy. Seeing your quote made me recognize my fat fingers had dropped a letter in Hesperoperla, but I have fixed it now.
  13. You are right guys...my mistake. Correct taxanomic nomenclature:


    Species:americana...and/or possibly curvata

    Hesperoperla (Which I guess is the true "Golden Stone")

    Order and Suborder same
    Subfamily: Acroneuriinae
    Species: pacifica

    I was flying through my key way too fast...missed a number. Just goes to show you can't believe everything you read on the internet. Thanks for paying close enough attention to catch my error guys.

  14. The easiest way to tell the difference is by relative cerci (tail) length (for adults on the wing). For larva, Perlids have hairy (gills) armpits and a species specific pattern on their head capsule.....Classenia sabulosa has an "M" above the eyes, Acroneuria has a "keyhole". Never seen a Hesperaperla pacifica, but it has it's own failsafe identifying pattern. Chances are, if the perlids are there, the perlodids are too, unless you go far downstream in the drainage.
  15. ShowMeFish makes some good points concerning recognition of the stoneflies previously discussed in the thread.

    There are only (4) species of Perlids (Common Stones) present in WA, and their head capsules look like this:
    Calineuria californica (Western Stone)
    Claassenia sabulosa (Shortwinged Stone)
    Doroneuria baumanni (Cascades Stone)
    Hesperoperla pacifica (Golden Stone)

    On the other hand, there are (29) species of Perlodids (Patterned Stones) present in WA. However, (1) genus and (2) species are more likely than the others to be observed:
    Skwala americana (American Springfly)
    Skwala curvata (Curved Springfly)
  16. Too much information. My brain hurts
  17. Hmmm. That generally only happens when one overuses a muscle which doesn't get much exercise.:)

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