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Saturday, February 21, 2015

Which blue?

This wonderful butterfly sent me down a bit of a frustrating path tonight.  It's a "tailed blue" can you see the "tails" trailing off the back edge of each hind wing?  They're hard to see in the field, so you have to look carefully.

Even though I haven't seen one in California yet, my first thought was, "Okay, this is going to be a Western Tailed Blue (Cupido amyntula)."

But then when I started doing some research, I learned that Eastern Tailed Blues (Cupido comyntas) are also present in some parts of California.

So now the question iswhich of the tailed blues is this?

Unfortunately, I don't have my butterfly field guides with me right now.  And when I tried to find out how to separate the two species online, I had a hard time tracking down useful information.  Then I reviewed pictures of the two species.  I've seen lots of Eastern Tailed Blues (on the East Coast), but not many Western Tailed Blues. 

I'll also reveal that I didn't get very good looks at the underside of this butterfly (although it looked quite pale).

After all of this, I still couldn't decide which one this was — a Western Tailed Blue or an Eastern Tailed Blue.

So...I'll either have to ask around for help from people with more experience, or wait until I have access to some butterfly books that perhaps can help point me to characters that might separate the two species.  Can you help?

Here's a slightly different view:

Photographed at Crane Creek Regional Park in Santa Rosa on 21 February 2015.

1 comment:

Alexan said...

Lovely photo! It would be a new one for me, since I never learned the eastern NA leps!
And I do think you are correct on the ID since the Western Tailed Blue has little to no orange topside,hindwing. Shapiro says the Eastern on this side of the Divide appears with little to no orange! Mighty confusing.
Alexandra Mc Donald