How to Keep a Caterpillar

of 05

How to Handle Your Caterpillar Safely

Don't handle the caterpillar with your fingers. Instead, use a leaf to gently touch the caterpillar on the rear end. The caterpillar will walk forward, making it easy to coax onto another leaf or your hand.
Debbie Hadley/WILD Jersey

Caterpillars can cling to a surface with remarkable strength when you're trying to pick one up. You don't want to hurt it, so you should know a few things about how to handle your caterpillar properly.

Rather than try to pick the caterpillar up, place a leaf in front of it and give it a gentle nudge on the rear end. Usually, when a caterpillar is touched from behind, it will walk forward to avoid the touch. The caterpillar should walk right onto the leaf. Carry the caterpillar to a container on the leaf.

Quite a few caterpillars have spines or hairs that appear soft and fuzzy, but can actually produce a nasty little prickle and irritate the skin. Tussock moth caterpillars, for example, may cause a painful rash. Some caterpillars can sting—don't ever handle one with bare hands!

of 05

Provide the Right Housing for Your Caterpillar

What you need to set up a caterpillar habitat: a container, some soil or sand, food and a small jar of water to keep the food fresh, cottonballs to prevent caterpillars from falling into the water, and a stick for pupating.
Debbie Hadley/WILD Jersey

You don't need a fancy insect terrarium to raise a caterpillar. Just about any container large enough to accommodate the caterpillar and its food plant will do the job. A gallon-sized jar or old fish tank will provide a luxurious and easy to clean home. Once you have a suitable container, you'll need to add a few things to give the place a "homey" feel.

Since some caterpillars burrow in the soil to pupate, it's a good idea to line the bottom of your container with about an inch of slightly moist sand or soil. The soil should not be too wet—you don't want to end up with condensation on the sides of your jar. Other caterpillars hang from twigs or other surfaces to pupate. Add a stick or two, secured in the soil and leaning against the side. This also gives the caterpillar a way to climb back on its food plant, should it fall off.

To keep the caterpillar's food plant fresh, place the stems in a small jar of water. Fill any space between the stems and the lip of the small jar with wadded paper towels or cotton balls to prevent your caterpillar from falling into the water and drowning. Put the small jar with the food plant into the caterpillar jar.

When the butterfly or moth emerges, it will need a place to cling while it unfurls its wings and dries them. Once the caterpillar pupates, you can tape a paper towel to the wall of the jar or aquarium to give the adult a place to cling. Place the tape at the top, and allow the paper towel to hang freely to the bottom. Sticks also work well for giving the butterfly or moth a place to hang.

You don't need to provide water—caterpillars get their moisture from the plants they consume. Cover the jar opening with a fine mesh screen or cheesecloth, and secure it with a rubber band.

of 05

Provide the Right Food for Your Caterpillar

When you find a caterpillar on a plant, take cuttings of the plant. Offer this plant for food first - it's probably the host plant.
Debbie Hadley/WILD Jersey

If you don't know for sure what kind of caterpillar you've found, feeding it can be tricky. Most caterpillars are herbivores, eating only plants. Some caterpillars feed on a variety of food plants, while others consume only a specific plant. You can't force a caterpillar to eat something different—it will simply stop eating. A little trial and error may be required to find the proper food for your caterpillar.

Your first and most important clue is where you found the caterpillar. Was it on a plant? If so, there's a good chance that's its food. Take some cuttings of the plant, and be sure to include both new and old leaves, as well as flowers if the plant has bloomed. Some caterpillars prefer old leaves to new ones, and others may feed on the flowers. Offer the cuttings to your caterpillar, and see if it eats anything.

If the caterpillar was not on a plant at the time you found it, you'll have to make some educated guesses about what to feed it. What plants are nearby? Start with those, taking cuttings and offering them to the caterpillar. If it eats one, you've solved the mystery and should continue to collect that plant for feeding.

If you're still really stumped about the caterpillar's food preferences, you can try introducing one or more of the most common caterpillar food plants: oak, willow, cherry, poplar, birch, apple, and alder. Some herbaceous plants, like dandelions and clover, are also common hosts for larvae. When all else fails, try a few bits of apple or carrot.

Whatever your caterpillar does eat, you will need an abundant supply of the food plant. Remember, a caterpillars job is to eat and grow. As it gets bigger, it will eat more. You need to keep a fresh supply of food available to the caterpillar at all times. Change the food once most of it has been eaten, or if it starts to wilt or dry out.

of 05

How to Keep Your Caterpillar's Home Clean

Change the foodplant when it becomes dry or well-eaten, and remove any caterpillar droppings (seen on the cotton ball) regularly.
Debbie Hadley/WILD Jersey

Since caterpillars eat a lot, they also produce a lot of droppings (called frass). You'll need to clean out the caterpillar's housing regularly. When the caterpillar is on its food plant, it's a fairly easy process. Just remove the food plant and the caterpillar, and let it continue munching away while you clean house. Make sure you clean out the small jar holding the food plant, too.

If conditions become too moist in the housing, you may discover fungus forming in the soil layer. When that happens, be sure to remove the soil completely and replace it.

of 05

What to Do After the Caterpillar Pupates

Once the caterpillars have finished eating and growing, they will pupate. You won't need to do much but wait to see your butterfly or moth emerge.
Debbie Hadley/WILD Jersey

You won't need to do much once the caterpillar successfully pupates. Remove the food plant. The pupa can dry out if conditions become too dry, or become moldy if too damp. Some butterfly and moth keepers recommend removing the pupa from the caterpillar housing, but this isn't necessary if you check the jar once in a while. If the soil appears extremely dry and crumbly, a light spray with water will add a little moisture. If condensation appears on the jar, wipe it down.

Spring and most summer caterpillars may emerge as adults within a few weeks after pupating. Fall caterpillars usually overwinter in the pupal form, meaning you will have to wait until spring to see the moth or butterfly. I recommend keeping any overwintering pupae in a cool basement or unheated garage, to prevent premature emergence. You don't want a butterfly flying around your home in winter! If you're collecting caterpillars in the fall, be sure to read my tips for keeping a caterpillar through the winter.

When the adult emerges, it will need time to dry its wings before it can fly. This may take a few hours. Once it is ready to fly, it may begin fluttering its wings rapidly, which can damage its wings if the butterfly or moth is left in the jar. Take the jar outdoors, preferably to the area where you collected the caterpillar, and release your butterfly or moth.