The life cycle of painted lady butterflies was a big topic of study for elementary students in Smithville, NJ, last year, so science resource teacher Carol Ann Margolis ordered caterpillars from a science supply company. "Although students fed caterpillars the nutrient culture that came with them," says Carol Ann, "we had also been studying "host" plants that butterfly larvae feed on in nature and students wondered about growing some of our own 'natural' food for catepillars." Their research revealed that painted lady butterflies often lay eggs on members of the mallow family, which includes hollyhocks, so the class decided to try growing some in the GrowLab.
Students started hollyhocks in February, then in May placed them in a butterfly box with mature painted lady butterflies that had hatched from a chrysalis formed by the larvae. In days, reports Carol Ann, the students were able to observe the mature butterflies mate and lay eggs on the hollyhock leaves. "The kids were amazed to see the tiny specks on the leaves actually hatch and begin to feed on the hollyhocks less than a week after we said goodbye to the adult butterflies. We left only a couple of the caterpillars on the leaves and raised the rest on nutrient culture. Those on the hollyhocks grew as well as the others, decimated the leaves, then began to form chrysalises themselves. It was a great opportunity for my kids both to experience life cycles and to appreciate this relationship between plants and animals. They're much more observant now of caterpillars outdoors and what they feed on."
Carol Ann recommends starting hollyhocks two to three months before your butterfly larvae arrive, but feeding only the nutrient culture to the first batch of larvae. Once you have a chrysalis, you can introduce the hollyhocks into the butterfly container and observe the mature butterflies emerge. If you have both butterfly sexes, they'll hopefully mate and lay tiny eggs on your homegrown larvae food, beginning the cycle again. Since caterpillars have such voracious appetites, she recommends removing all but a few to feed on the hollyhocks.