How to Feed and Care for a Caterpillar

Preparing the Habitat Is a Key to Its Survival

While a caterpillar might not replace a cat or dog as a pet, keeping one can be interesting, especially if you get to see it transform into a butterfly or moth. Here are some steps to take to help the caterpillar thrive.

01
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Handle Your Caterpillar Safely

Leaf preparation for caterpillar habitat
Handle Your Caterpillar Safely. Debbie Hadley/WILD Jersey

Caterpillars can cling to a surface with remarkable strength. If you're trying to move one you don't want to hurt it, so you should know how to handle your caterpillar properly.

Rather than try to pick up the caterpillar, 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. Then carry the caterpillar on the leaf.

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

02
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Provide the Right Housing

A container, some soil or sand, food and a small jar of water, cottonballs, and a stick
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-size jar or old fish tank will provide a luxurious, 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 an inch of slightly moist sand or soil. The soil shouldn't 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. For them, add a stick or two, secured in the soil and leaning against the side. This also gives the caterpillar a way to climb back onto 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 jar with wadded paper towels or cotton balls to prevent your caterpillar from falling into the water and drowning. Put the 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.

03
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Provide Proper Food

Caterpillar on a leaf
Debbie Hadley/WILD Jersey

If you don't know 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. 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. If it was on a plant, there's a good chance that's its food. Take some cuttings of the plant, including 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 wasn't on a plant at the time you found it, you'll have to make some educated guesses about what to feed it. Start with the nearby plants, 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 stumped about the caterpillar's food preferences, try introducing one or more of the most common caterpillar food plants: oak, willow, cherry, poplar, birch, apple, and alder. Some herbaceous plants, such as dandelions and clover, are common hosts for larvae. When all else fails, try a few bits of apple or carrot.

Whatever your caterpillar eats, you'll need an abundant supply. A caterpillar's job is to eat and grow. As it gets bigger, it will eat more. You must 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.

04
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Keep Your Caterpillar's Home Clean

Leaves for feeding caterpillar
Debbie Hadley/WILD Jersey

Since caterpillars eat a lot, they also produce a lot of droppings (called frass). You should clean out the caterpillar's housing regularly. When the caterpillar is on its food plant, it's a fairly easy process: 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 the housing becomes 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.

05
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What to Do After the Caterpillar Pupates

Caterpillar pupa
Debbie Hadley/WILD Jersey

You won't need to do much once the caterpillar pupates, but you should remove the food plant. The pupa can dry out if the habitat becomes too dry or become moldy if it's 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 of 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. Keeping overwintering pupae in a cool basement or unheated garage will prevent premature emergence. You don't want a butterfly flying around your home in 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 the 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 set it free.