To make your own hatching chamber for butterflies, you'll need:
* 2-liter plastic soda bottle
* caterpillar, along with leaf on which it was found
* leaves of host plant
1. Find a caterpillar on a plant so you'll know what food it prefers. Don't pull the caterpillar off the leaf, just remove the leaf from the plant. Collect several more leaves and twigs from the host plant.
2. Cut off the upper several inches of a 2-liter plastic bottle, down to where the straight portion of the bottle begins, and discard the cut-off portion. Run hot water inside the base to loosen the glue and separate the base. Put aside the lower portion of the bottle that fit inside the base. Add moist, sterile potting soil, sand, or gravel to the base.
3. Add the caterpillar and leaf, along with some twigs with leaves of the host. Invert the lower portion of the bottle, place it over the base, and punch small holes in the top for air circulation. (If you have very small caterpillars, glue screen or netting over the holes to prevent their escape.)
4. Add fresh leaves of the host plant each day, and use a paintbrush to remove the waste, called frass. (You can place sprigs of the host plant in a small-necked bottle of water to keep them fresh, then put that in the chamber. Don't leave a container with open water, since caterpillars can't swim.)
5. Add some extra twigs to give the larvae a place to crawl when it pupates. Leave the container in a warm location out of the sun for a week or two until the caterpillar forms a chrysalis. Keep a close watch during this fascinating phase. Your butterfly should emerge in about two weeks. Once its wings are dry and rigid (in about four hours), you can release it into your garden if the weather is calm.