I have no idea. I never tracked one. However, horn worms don't eat Stevia. If you want to support these caterpillars I suggest you grow a tomato just for them. The bad news is they will increase in numbers as time goes on so you may be growing more feeder plants then eating plants. Happy Yardening, Nancy
CoHabitation With Hornworm Caterpillars
Question From: D. Savel - CALIFORNIA
Q: Hi Nancy, I just found a big ol/ hornworm caterpillar in my tomato plant and not wanting to kill it, I relocated it in my Stevia plant across the yard. This morning, it was gone. I looked all over for it. How fast can these bugs travel???