Subject: Transparent-winged butterfly
Location: Mt. Bross 12,000ft elev.
September 7, 2014 12:27 pm
I shot this butterfly on Sept 6, 2014 on Mt. Bross in Park County, colorado at an elevation of about 12,000 ft. I think it’s a Rocky Mtn. Parnassus or maybe a Checkered White. Its wings were mostly clear and it appeared to have no trouble flying around for half an hour before i finally got a few shots if it resting. I’ve never seen a clear-winged butterfly before, do you think it’s a mutation or is it possible that the color somehow got washed off in all the rain we’ve been having this summer.
Signature: Bob

Rocky Mountain Parnassus

Rocky Mountain Parnassus

Hi Bob,
We agree that this is a Rocky Mountain Parnassian,
Parnassius phoebus, a species which Jeffrey Glassberg, in his book Butterflies Through Binoculars The West, calls the Phoebus Parnassian, though he acknowledges it has several subspecies including Parnassius phoebus smintheus.  According to BugGuide, the Rocky Mountain Parnassian is Parnassius smintheus, and BugGuide provides the following information:  “Antenna has alternate black and white rings. Upperside of forewing of females and most males with 2 red or yellow spots beyond the cell. In some males these spots are black.(1)  Often called by the name Parnassius phoebus, a closely related Eurasian species. Many people consider all North American populations to belong to that species, many prefer to separate them. Some authors split North American populations into more than one species; usually two or three, with the northernmost populations included in P. phoebus, and the rest in P. smintheus; or, the Sierra Nevada populations may be separated as Parnassius behrii. These regional ‘species’ are best distinguished by where they are found.”  Isolated populations often exhibit localized variations, so individuals on one mountain may look different from individuals on the next mountain.  Regarding the transparency, we believe this is a result of the loss of scales that might be a natural occurrence in the species as BugGuide includes many images of more transparent individuals.

Location: Mt. Bross, Colorado

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