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Rearing Caterpillars IN THIS F@STSHEET WHY REAR CATERPILLARS? HOW DO I GET STARTED? FOR MORE INFORMATION

        Rearing caterpillars makes a great summertime science experiment. Best of all, it's easy. All you need are caterpillars (or eggs), some of the plant the caterpillars were found on, and a container or bag to hold both plant and insect.

WHY REAR CATERPILLARS?
        Besides being fun, you can learn a lot about caterpillars by rearing them to adults.  Rearing caterpillars is a great way to learn more about the insect life in your garden. How long do they take to turn into adults?  What plants do they feed on?  How fast do they grow at different temperatures?  What are their natural enemies?  Many of these questions can be answered by careful observation of feeding caterpillars.  Rearing can also help with identification.  Caterpillars are often difficult to identify, even for experts; but lots of good books are available to help you identify moths and butterflies.

HOW DO I GET STARTED?
        First locate some feeding caterpillars.  Look on garden plants ...vegetable gardens are usually full of caterpillars.  Cabbage and broccoli are favorite foods of the cabbage looper and the cabbage butterfly.  Milkweed is a good place to look for monarch caterpillars.   Actually, nearly any tree or plant can have caterpillars, if you have sharp eyes.   Look for chewed leaves or "frass."  Frass is another name for caterpillar feces.  It is often present just underneath where a caterpillar is feeding.  Some of their natural enemies find their caterpillar prey by looking, and smelling, for caterpillar frass!
        Once you have your caterpillars, you'll need to find them some suitable food.  Caterpillars won't feed on any plant--they are often quite choosy. Feed them the wrong food and they'll starve. It's best to put your caterpillar with branches from the plant on which they were found.
        Caterpillars can either be caged on the plant where they were found, or put into a cage you make.  A lightweight mesh bag can sometimes be slipped over the branch where the caterpillar is feeding.  When tied securely, this protects the caterpillar from its enemies, like birds, and keeps it from wandering away.  Be sure your "cage" is light enough to allow sunlight through and not cause the plant to bend too much.
        You can make a simple rearing cage from a 2-liter soda bottle, margarine tub (I Can't Believe It's Not Butter tubs are perfect), some tape, a small piece of muslin or other light cloth, and a rubber band.
        Cut the bottom from the soda bottle and poke some small holes around the top for ventilation.  Make an X cut in the top of the margarine container. This is where you'll slip the plant branch.  Fill the margarine tub with water and slip the base of the plant or branch through the opening in the top of the container.
        Put the caterpillar on the plant and place the soda bottle over plant and tub.  Seal the tub and bottle together, if you like, with masking tape to keep your cage from accidentally coming apart.  Finally, remove the bottle top and replace with a small piece of muslin secured with a rubber band.
        The pupal stage is that mysterious part of metamorphosis where the caterpillar changes into a beautiful moth or butterfly.  A large caterpillar shouldn't take too long to finish feeding and pupate.  Smaller caterpillars or eggs may require 3 or more weeks to enter the pupal stage. A mature caterpillar may appreciate some leaves or other dry material on the bottom of the cage in which to pupate.  The pupal stage itself may take 2-3 weeks.
        Once your caterpillar has pupated, remove all the remaining green plant material.  The secret to keeping caterpillars and pupae alive is to give them just enough-not too much-humidity.  Wipe off any condensation from the inside of the container every day-don't place the cage in direct sunlight.   A little water in the bottom of the margarine container, along with ventilation holes in your cage, should give your pet about the right amount of humidity.  Never put water directly on a caterpillar or pupa being held in a cage.
        Give your butterfly or moth something to crawl on when it emerges.  Place a stick or vertical piece of rough paper towel in the cage.  This will give the fragile new creation a place to hang while its wings expand and harden.
        If you collected your caterpillar in the fall, and the pupa does not emerge within three weeks, you may need to fool it into thinking winter has come and gone. Place your pupae into a refrigerator for 2-3 weeks.  After refrigeration, return to room temperature and wait. With any luck, some morning you will see a large showy moth or butterfly hanging from the branch in your jar.
        Feed adult butterflies on honey water and hold them for several days, or else let them go outdoors.  Be sure to make a drawing, or take a picture, to help you remember your friend.

FOR MORE INFORMATION
       For more information about rearing caterpillars, several excellent field guides are available to help you identify your insect captives. I recommend the Peterson series. It includes:
        Peterson Field Guides. R.T. Peterson, Editor. Found in almost all good book stores, these guides have both black and white and color illustrations. Different volumes are available on butterflies and moths of eastern and western North America.
        The Peterson First Guide to Caterpillars (by Amy Bartlett Wright, 1993) is an excellent guide to the most common caterpillars. The guide groups common North American caterpillars by easily seen characteristics.
Another excellent guide to caterpillars is Butterflies of Houston and Southeast Texas by John and Gloria Tveten. 1996. University of Texas Press. This book contains beautiful photographic images of butterflies and caterpillars of a large number of Texas species.  

Author:
Michael Merchant, Ph.D., Urban Entomologist, Texas Agricultural Extension Service
Special thanks to Boy's Life magazine for use of illustrations.

Publication information:
This publication is part of the House & Landscape Pest Series produced by the Department of Entomology, Texas A&M University, College Station, TX 77843-2475. The most recent update can be found at: http://dallas.tamu.edu/insects/FastSheets/Ent-3002.htmll . Series Editor: M. Merchant. For more information about arthropods, check out the Texas A&M Entomology Website at http://insects.tamu.edu/
Last revision: 10/9/01