Saturday, December 29, 2012

Duskywings: Dreamy vs. Persius

As I seem to only be posting once a month, I figured I had better put something together before the new year!  Between being sick for a week and busy with Thanksgiving and Christmas, I haven't had time to work on the guide to preserve and mount specimens as I promised in my last post, but hopefully I will get to that soon.  In the meantime, I thought I might give you a lesson in differentiating Dreamy and Persius duskywings (Erynnis icelus and persius), mostly because that is what I've been struggling with today while working on my Sinlahekin butterfly guide.  I'm fairly certain that I've identified these photos correctly, but if anyone reading this disagrees, please let me know by leaving a comment, I'd appreciate it!

Dreamy Duskywing Erynnis icelus
This is the only duskywing species in the Northwest that does not have the group of submarginal white spots on the dorsal forewing.  Dreamy Duskywings also tend to have a more purplish-gray frosted appearance, compared to the brownish-gray of the Persius Duskywing, although this is not a reliable method of identification.  The Dreamy Duskywing's larval host is primarily willow, and the adults are frequently found in moist meadows and along streams where willows are found.
Dreamy Duskywing, Sinlahekin Wildlife Area, Okanogan County, WA
Dreamy Duskywing, Sinlahekin Wildlife Area, Okanogan County, WA

Persius Duskywing Erynnis persius
Persius Duskywings have a group of submarginal white spots on the dorsal forewing that set them apart from Dreamy Duskywings, although these markings are difficult to see in faded individuals.  Larval host plants are primarily lupine species, although species of milkvetch (Astragalus) and deervetch (Lotus) have also been recorded.
Dreamy (left) and Persius (lower right) duskywings with Boisduval's blues, SWA
Persius Duskywing, Sinlahekin Wildlife Area, Okanogan County, WA


  1. Caitlin,
    Thanks for the photo-based duskywing ID workshop...helpful for Montana observations. Perhaps you could do another such effort concentrating on Fritillary of the Pacific Northwest. Enjoy your blog...Happy New Year

    1. Thanks for your kind comments, I'll definitely do a fritillary ID post, can't imagine why I didn't think of that before, considering I still struggle with those! I'm not familiar with some of the species you probably have in Montana, but I'll do my best with the ones I know of and have photos for.