Peter,
 
Wagners Caterpillar book is probably the best...
 
I'm not that good at it either...
 
And I wasn't suggesting that this is not a Black Swallowtail, necessarily...It's just that we've been finding some strange "Black Swallowtails" in central and northern New England...Just ask Dave Hoag, for example...
 
Alex 

From: Vermont Butterfly Survey [mailto:[log in to unmask]] On Behalf Of Peter Manship
Sent: Monday, July 12, 2010 10:04 AM
To: [log in to unmask]
Subject: Re: ID Help

Alex,
 
I'm not that good at ID'ing caterpillars so it could be something else. Really don't know.
 
 I'm looking for a good book on caterpillars, any suggestions?
 
Peter
----- Original Message -----
From: [log in to unmask]" href="mailto:[log in to unmask]">Grkovich, Alex
To: [log in to unmask]" href="mailto:[log in to unmask]"> [log in to unmask]
Sent: Monday, July 12, 2010 8:30 AM
Subject: Re: ID Help

Peter,
 
I would suggest that the Black Swallowtail caterpillar is eating his old exoskeleton...
 
By the way, that is a rather unusual coloration for a polyxenes asterius...
 
Alex

From: Vermont Butterfly Survey [mailto:[log in to unmask]] On Behalf Of Peter Manship
Sent: Sunday, July 11, 2010 8:24 AM
To: [log in to unmask]
Subject: ID Help

I was at Dead Creek WMA   Brilyea access road back by the turtle pond and found these cateplars and would like some help.
 
First,  can anyone ID the brownish hairy caterpillar ?
 
Second,   what is the correct way to describe what is happening in the image of the Black Swallowtail caterpillar ?
 
Thanks
 
Peter Manship

CAUTION PLEASE NOTE: The information contained in this transmission is intended to be sent only to the stated recipient of the transmission.
If the reader of this message is not the intended recipient or the intended
recipient's agent, you are hereby notified that we do not intend to waive
any privilege that might ordinarily be attached to this communication. Any
dissemination, distribution or copying of the information contained in this
transmission is therefore prohibited. You are further asked to notify us of
any such error in transmission as soon as possible at the telephone
number/email address shown above. Thank you for your cooperation.

CAUTION PLEASE NOTE: The information contained in this transmission is intended to be sent only to the stated recipient of the transmission.
If the reader of this message is not the intended recipient or the intended
recipient's agent, you are hereby notified that we do not intend to waive
any privilege that might ordinarily be attached to this communication. Any
dissemination, distribution or copying of the information contained in this
transmission is therefore prohibited. You are further asked to notify us of
any such error in transmission as soon as possible at the telephone
number/email address shown above. Thank you for your cooperation.