thoas swallowtail

Mark Walker MWalker at
Tue Sep 29 09:15:23 EDT 1998

Well, don't be too apologetic.  The literature can be confusing, and can
also be wrong.  And it isn't all that impossible that you run across
something that has never been recorded before.

In the case of thoas vs. cresphontes, the similarities are striking so it
would be difficult to get a positive id without capturing it (and these
butterflies are very difficult to capture).  The Giant Swallowtail has
certainly been recorded in SoCal, but I would not consider it to be a common
species.  It's presence fluctuates year to year, and any sighting is of
particular interest to butterfliers from California.  P. thoas is pretty
much a tropical species only, found mainly in the deep south in the U.S.

Personally, I've lived in California for almost 40 years and I think I might
have seen one P. cresphontes flying very high above Interstate 5 one year,
but I never got a good look.  So for what it's worth, your sighting is of
particular interest to me.  And the fact that you thought it was thoas is
pretty good verification that it wasn't a Tiger or some other common western
swallowtail.  As has already been suggested, you really ought to go one step
farther and see if you can't find out where it might have come from.  Check
out any citrus groves in your area.  The butterflies like to patrol in and
around the trees, often flying close to and around the trunks.

For your info, the USGS online countywide checklist for the United States is
quite useful, and can be a great compliment to your field guide.  Check it
out at:


	Mark Walker

> -----Original Message-----
> From:	J Shields [SMTP:truezane at]
> Sent:	Tuesday, September 29, 1998 12:09 AM
> To:	MWalker at
> Subject:	Re: thoas swallowtail
> Mark
> From the mail I've gotten, most people think that what I saw were giant
> swallowtails.  I need to get a better ID book than what I'm using.  I
> based my initial ID on a book which said that the giants didn't get this
> far west, but I've been getting e-mails telling me that they are indeed
> out here.  I found a better photo of a giant swallowtail and the yellow
> dot pattern on the wings is consistent with what I saw, so I guess
> that's it.
> Thanks for your reply
> J

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