This caterpillar is on a rue plant. Is it a black swallowtail?
Help identifying caterpillar
This forum is for questions relating to adding data to the BugFiles database.
We have a forum on Insect and Spider Identification here: http://davesgarden.com/community/forums/f/bugid/all/
and if you post your question there, you may get some help,
If you have an image, you could attach it to the message you post for a better chance of getting an identification
Having said all that, I can confirm that yours is the caterpillar of the Black Swallowtail - Papilio polyxenes: http://bugguide.net/node/view/705198/bgpage