Identification of caterpillar in Texas
It is the caterpillar of Papilio polyxenes.


  The pupae may be green or brown, but not depending on surroundings or the background on which they have pupated. The color of the chrysalis is determined by a local genetic balance that ensures the majority of pupae will blend in.[10] A section of the green pupae will turn a much darker green at the very end of the pupae stage. This color change occurs a few hours to a full day before hatching.[10] Unusually, this butterfly's chrysalis is girdled with a loop, with its feet attached to the silk pad, which helps the butterfly to unfold its very large wings when crawling out.[11]




Here is a photo of black swallowtail caterpillars at different life stages: 




Here is a link to a post, which describes all the stages your caterpillar will eventualy go through.