There are a lot places out there selling caterpillars and butterflies for use in the classroom or for learning at camps, at day cares, or at home. Read this and learn how you can raise your own caterpillars safely, easily, and cheaply.

What you'll need:

• Wire mesh trashcan
• Piece of window screen that will cover the top of the trashcan with enough extra material to secure it
• Large rubber band or bungee cords to secure screen over can
• Glass or plastic 20oz soda bottle
• Empty butter container filled with soil
• A stick long enough to place in bottle so that 6-8 inches stick out the top

What you'll do (and why):

• Find a caterpillar! Around your house, at your school, anywhere! It's okay if you don't know what kind of caterpillar it is. Caterpillars are almost always found on their host plant. This is the plant that they eat, because eating is just about all caterpillars do. Caterpillars are picky eaters, many times only eating one kind of plant. Many people fail at raising caterpillars because they try and feed them something other than their host plant. A caterpillar will die before trying a new food. I told you, they're picky! You don't have to know what the plant is that you find the caterpillar is on, but you MUST know where to find more. You might want to flag the plant or tree to make it easy to find again.
• Clip the portion of the host plant with the caterpillar on it. Fill the bottle with water and put the end of the plant without the caterpillar down into it. The bottle has a small enough mouth that the caterpillar should not fall in (they aren't good swimmers).
• Place the bottle at the bottom of the mesh trash can. You now have a perfect caterpillar home. You just need to do a few more things if you want to see this guy (or girl) turn into a moth or butterfly.
• Place the stick in the bottle. Some caterpillars will want to make their chrysalis (moths make a cocoon, butterflies form a chrysalis) hanging off of a hard surface like a stick.
• Place the butter container filled with soil right next to the bottle on the bottom of the trash can. Some moth caterpillars like to pupate (turn into an adult) in soil, so it's a good idea to have some there if you don't know what kind of caterpillar you've found.
• Cover the trashcan with the window screen and secure it taught with a rubber band or bungee cord. There are several reasons for this. Caterpillars usually stay on their host plant until they are ready to pupate. If you want to watch them pupate, you better cover the top. Also, so caterpillars like to form their chrysalis hanging from the top. This is my a mesh trashcan is suggested. Other materials are often too slick for caterpillars to climb up. Finally, this will protect your caterpillars from predators.
• Your butterfly emergence chamber is now complete!

A few more VERY IMPORTANT notes:

• Check the host plant food supply every day. Caterpillars eat a lot and have to keep eating if they are going to pupate. Always keep a fresh supply available.
• You should keep your butterfly cage in a sheltered area OUTSIDE. Temperature and day length help determine time of emergence for some moths and butterflies, so they must be exposed to these elements while pupating.
• What are all of those pellets at the bottom of your trashcan? Caterpillars actually do one other thing besides eat! Their waste is called frass, and it must be dumped out of the can every few days.
• Check your cage every day when waiting for a butterfly to emerge. They will need to eat soon. When they emerge, they will need a few hours for their wings to dry. Many will hang from the top until they are ready to fly. Once they are ready to go, simply take the screen off the top and set your butterfly free!

Benefits to the above method of caterpillar rearing:

• It's cheap! You should spend no more than $10 on supplies.
• It's easy!
• You reuse household items.
• You learn about the critters in your own environment.
• You are releasing butterflies and moths that are naturally found in your environment.
• You can raise lots of different kinds of caterpillars which is great for learning.

Written by Rachel Golden, Office of Environmental Education