A cocoon is a covering which an insect larva forms around itself and in which it passes the pupa stage [source: Merriam Webster]. There are four stages in a butterfly's life cycle. First, the female butterfly lays eggs on plants. Then the caterpillar emerges from the egg [source: AMNH]. During this stage the caterpillar grows by eating plants and other vegetation. When the caterpillar is fully grown it becomes a pupa. It's at this stage that it will hide among leaves and spin a cocoon around itself. It will remain in this stage until it breaks out of the cocoon as a butterfly. The final stage is when it becomes a full-grown adult butterfly, and then the process begins all over again [source: ANS]. Here's how to care for butterfly cocoons at home.

  1. Place a small plant in a pot or vase in a large, wide-mouthed jar.
  2. Lean several branches against the wall of the jar. This will provide a place for the caterpillar to attach itself and spin its cocoon.
  3. Place a paper towel along one side of the jar. When the adult butterfly emerges it will use the paper towel to spread its wings and let them dry.
  4. Place some moist paper towels on the bottom of the jar to keep the moisture level in the jar elevated.
  5. Place some caterpillars in the jar. Note what type of plant you found the caterpillars on.
  6. Cover the jar with a cloth and secure the cloth with a rubber band.
  7. Place fresh leaves in the jar daily. Since caterpillars eat a lot, you'll have to supply a few fresh leaves each day.
  8. Clean the jar out whenever you notice it getting dirty. This is important to prevent mold from growing. Replace the caterpillar and all the accessories after cleaning the jar [source: University of Arizona].
  9. Spray some water in the jar from time to time, after the butterfly pupates. Other than this, the cocoon won't need any other care [source: butterfly school]. //]]]]> ]]>