I did read that cruciferous vegetables are host plants for this butterfly. But most cruciferous vegetables are a winter crop in my Southern garden. The pretty little butterflies seem pretty indiscriminate about which plants they hang out near and light on - the artichoke, asparagus, bolting kale, fennel, along with grass weeds that have gone to seed . . . My fear of removing what has attracted them led me to not pull or trim one single horrible looking plant. This afternoon, when I went out to cut a kale leaf for a smoothie, the kale was covered in caterpillars!
A quick google search verified that these are indeed Southern Great White butterfly larvae! If you want to see the entire life cycle, visit this post by the Dauphins, a couple of butterfly experts in south Texas. They captured every detail in some fabulous photos! The chrysalis isn't as pretty as some, but I will be on the search for them in a day or two.
If your schedule - or the Texas heat - keeps you from keeping your garden as tidy as you'd like, don't despair. You may get to play host to some lovely little creatures, too!