Hill Topping Quandary on Lewis Butte

Oregon Swallowtail, Papilio machaon, ranges from central to eastern Washington but has rarely been observed in the upper Methow valley. On many occasions I’ve looked at Anise Swallowtails, P. zelicaon, trying to find a P. machaon. Dale Swedberg led a Sinlahekin Wildlife Area field trip in July 2021, east of the Methow. There, I finally saw my first P. machaon in a grassy meadow near Conners Lake. Ever notice once you observe a butter- fly, you can finally see what the field guides are talking about?

P. machaon and zelicaon can be differentiated by features listed in the table below (see also Butterflies of the Pacific Northwest, http://northwestbutterflies.blogspot.com/2015/05/species-profile-swallowtails.html). The yellow abdomen is prominent on P. machaon as is the yellow dusting on the leading edge of the forewing. Close inspection shows the pupil or bar uncentered on P. machaon while centered in P. zelicaon. See photos.

P. machaon	P. zelicaon
Yellow abdomen with thin black stripes on top and sides along its length	Black abdomen with yellow side stripes along its length
Brighter and more yellow on elongated FW	Butter yellow on mostly black shorter FW
Black pupil, bar or spot at the bottom of red, not centered	Round black centered pupil surrounded by red
Yellow dusting over black on the leading edge of the DFW	DFW leading edge mostly black

Oregon on left, Anise on right. Note yellow dusting on Oregon, and the position of the eyespots on the hind wings.   Â

July 25, 2022, after a morning of gardening, I had time for a quick trip to Lewis Butte in Winthrop, WA. I was hoping to see some hill topping skippers. It was 80ish degrees at the start of my walk with water bottle in my pack and net in hand. Given the temperatures and late start I had the trail to myself. Along the way I noted 2-3 Wood Nymph species, Behr’s Hairstreak, Western Branded Skipper, and Western Whites flying about and nectaring on the few remaining Yarrow and Tall Buckwheat in bloom.  I thought about turning around given the heat and limited butterfly nectar sources but I was hoping the hill toppers would be worth the 2.5 mile one way, 900′ hike. On top, I looked closely at many skippers which were all Western Branded, Hesperia colorado. As my focus switched to the swallowtails flying about, I thought them to be the more common, frequently hilltopping, P. zelicaon. One however, landed briefly enough to see brighter yellow on the wings and a mostly yellow body. Could it be a P. machaon? It’s subtle but P. machaon is slightly larger. It was a good thing I had Lewis Butte to myself. I was not putting on a good netting demonstration. Thankfully my target landed just long enough to get a quick cell phone photo and I surely thought it P. machaon. On top of the butte, I had cell signal and sent it Jon Pelham to ensure the photograph was sufficient to verify the observation. He was skeptical but intrigued by the image. He started texting features mentioned above. Yellow body… Yellow dusting… Yes, I “know”. I was hoping to document it “was” P. machaon, so I sweated it out in the heat for another half hour, spinning this way and that trying to get a bead on one of them or hoping one would land again. I finally was able to net, photograph, confirm and end Jon’s suspense. Next time, I’ll arrive a bit earlier, take a second bottle of water and possibly bring a second netter, photographer to help. Little did I know then, that Oregon Swallowtails would show up at my home on 3 occasions later in the season (August 7, 19, and 29). I‘m still looking nearby for the host plant Wild Tarragon (Artemisia dracunculus) which is found on Methow Valley hillslopes further south.

Photos by Cheryl Bellin.

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