I found this while clearing out a place on our acreage in town. We live on the Texas Coast in the coastal plains, in Calhoun County. There were three of them on a Chinese Tallow branch that I trimmed. I couldn’t find any damaged leaves around them, so they may have just been on the move. I found them on my oleander plant this morning, just “chillin.” Other plants nearby where I found them – dewberry, lantana, Texas persimmon, poison ivy (I didn’t get into that, don’t worry!) Mustang grapevine, tickseed, thistle, wild chives. We have more but they are much farther away from the spot. Hope you can help – my son and I are very curious. I couldn’t find them on BugGuide or What’s That Bug. Thanks –
Searching our archives at What’s That Bug?, as well as searching the archives of our favorite identification site BugGuide (and BugGuide is way more organized than we are), can be a daunting task if you don’t know exactly what you are searching for. Both of our sites have numerous images of your species, the Pipevine Swallowtail Caterpillar, Battus philenor. Interestingly, none of the plants you mention are host plants for the caterpillar. According to BugGuide: “Larvae feed on Aristolochia species. These include ‘Pipevine’ or ‘Dutchman’s Pipe’, Aristolochia species ( tomentosa, durior, reticulata, californica ), as well as Virginia Snakeroot, Aristolochia serpentaria. Larvae presumably take up toxic secondary compounds from their hostplant.” Your photo indicates this is probably the final instar for the caterpillar and it is getting ready to metamorphose into a chrysalis. If that is true, the caterpillars might be wandering away from the plant that they were eating in search of the perfect location for pupation.