My daughter wanted to plant her own garden outside, so I made a 2x2' box for her to plant a few things in. I specifically made it small so that she could easil

My daughter wanted to plant her own garden outside, so I made a 2x2' box for her to plant a few things in. I specifically made it small so that she could easily weed it and whatnot. She planted fennel in there, and boy did it take off. It escaped the box and now I find little sprouts of it everywhere and it smells like Italian sausage whenever I cut the grass. Anyway, it turns out that swallowtail caterpillars love fennel. Each fall I collect fennel branches with caterpillars on them and keep them in a mesh canvas container in the garage. They form their chrysalis and seemingly go into suspended animation from about October until late May / June of the next year when they emerge as butterflies. I collected 11 of them last fall, and there were still more when I had run out of room in the container. That's from a a small 2x2' square, so imagine what an entire field of fennel could do!