How to Feed Caterpillars

Last Updated: October 22, 2021

Caterpillars make great pets, especially for kids. The typical caterpillar can be about 2.3 inches (6 centimeters) in length before advancing to the cocoon stage, and later becoming a butterfly. Caterpillars are typically herbivores, and eat a lot to fuel the change to a butterfly. There are several steps you can take to make sure your pet caterpillars are adequately fed in advance of the metamorphosis.

Part 1

Part 1 of 2:

Supplying Nurishing Food

1
Identify the plant the caterpillar was collected from. Take a photo or sample stem of the plant you collected the caterpillar(s) from. If you got the caterpillar(s) from a store, then make a note of what plants were in the original habitat. If you’re unsure, use a book on botany or ask a local garden shop or pet shop expert to help figure out what the plant was.^{[1]
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- Caterpillars have specific types of food plants related by species (there are at least 160,000 species of butterflies), and will only eat from that family of plants.^{[3]
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  Samuel Ramsey, PhD
  Entomologist
  Expert Interview. 20 January 2021.}
2
Clean the plants. Make sure the plants you select are thoroughly washed before you feed them to your caterpillars. Run them under water from a sink faucet, but don’t soak them so much they begin to wilt. Leave some droplets of water on the plants for the caterpillars to drink.^{[4]
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3
Put the plants in a glass of water. This is a good way to keep the plant supply fresh at least while the caterpillars are young.^{[6]
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Samuel Ramsey, PhD
Entomologist
Expert Interview. 20 January 2021.} Set up a glass of clean water just tall enough to fit in the caterpillar’s habitat. It can be a cup or even a small vase. Put the plants into the water, stalk first, and let the leaves rest up and over the top. Leave paper towels under the cup and plant to absorb any moisture or droppings.^{[7]
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4
Lay the plants along the bottom of the tank. This is an alternative to the glass of water method, but plants placed in this manner can dry up and rot faster. Place the stalk and leaves bunched along the bottom of the habitat. Allow them to rest along the length of the tank without running up the sides. If length is an issue you can use a pair of scissors to cut the stalk shorter. Leave the leaves intact.^{[9]
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Part 2

Part 2 of 2:

Replacing Old Food

1
Replace used food. As soon as you notice the leaves in the glass or on the bottom of the tank wilting, or see them eaten up, replace them.^{[11]
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Expert Source

Samuel Ramsey, PhD
Entomologist
Expert Interview. 20 January 2021.} What you replace the food with depends on the species of caterpillar you have. Some allow a more varied diet within the family of plants. If this is the case you should put in one of the other types. If the caterpillar does not eat it, then put the first type back in.^{[12]
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- Remember to wash the plants each time you replace them.
2
Change to other food plants. Only use this method if the species of caterpillar you have can eat multiple types of food plants within a plant family. Go to a local plant nursery and collect supply of the other plants in the family. Make sure you get intact leaves. Also make sure the plants are not treated with pesticides. Place only one of the varieties into the cup or tank bottom at a time. Watch if your caterpillar is eating the leaves. If not, then you should swap out to another variety.^{[14]
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- An example of plants in the same family would be leaves from apple, cherry, and plum trees. All come from the family “rosaceae.”
3
Put a variety of plants in the tank. This is a method to consider for multi-plant eating species only. You can leave a stalk of the original plant the caterpillar(s) came from in the glass or cage bottom. Add other food plants from the species-appropriate family of plants into the glass or tank bottom. Examine the leaves as you do this to make sure none are damaged or wilted before you put them in. If you notice the caterpillars ignoring one particular variety of plant, then you should remove it and not attempt to give it again.^{[17]
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- An example of a multi-plant eating species is the viceroy butterfly. The caterpillar can eat leaves from the willow, poplar, aspen, apple, cherry, and plum trees.
- Wash the plants before introducing them.

Expert Q&A

Question

Why does my caterpillar refuse to eat some leaves?

Samuel Ramsey, PhD
Entomologist
Dr. Samuel Ramsey is an Entomologist and a researcher with the United States Department of Agriculture. Dr. Ramsey has extensive knowledge of symbiosis and specializes in insect disease spread, parasite behavior, mutualism development, biological control, invasive species ecology, pollinator health, and insect pest control. He holds a Bachelor’s degree in Entomology from Cornell University and a Ph.D. in Entomology from the University of Maryland. Dr. Ramsey’s research on bees has enabled researchers to develop targeted control techniques to restore honey bee populations worldwide. He also hosts a YouTube series called “Dr. Buggs.”

Samuel Ramsey, PhD

Entomologist

Expert Answer

Caterpillars have taste buds. Different kinds of caterpillars eat only certain types of leaves. They eat soft leaves and do not like crispy leaves. If you do not give them the leaves of their choice, they will not eat them.
Question

Are caterpillars gregarious by nature?

Samuel Ramsey, PhD
Entomologist
Dr. Samuel Ramsey is an Entomologist and a researcher with the United States Department of Agriculture. Dr. Ramsey has extensive knowledge of symbiosis and specializes in insect disease spread, parasite behavior, mutualism development, biological control, invasive species ecology, pollinator health, and insect pest control. He holds a Bachelor’s degree in Entomology from Cornell University and a Ph.D. in Entomology from the University of Maryland. Dr. Ramsey’s research on bees has enabled researchers to develop targeted control techniques to restore honey bee populations worldwide. He also hosts a YouTube series called “Dr. Buggs.”

Samuel Ramsey, PhD

Entomologist

Expert Answer

Caterpillars like to have company. So you can raise a bunch of them together. But do not keep too many of them in a single cage. See to it that each of them has enough to eat and they are not overcrowded.
Question

When do woolly bear caterpillars go into their cocoons?

Samuel Ramsey, PhD
Entomologist
Dr. Samuel Ramsey is an Entomologist and a researcher with the United States Department of Agriculture. Dr. Ramsey has extensive knowledge of symbiosis and specializes in insect disease spread, parasite behavior, mutualism development, biological control, invasive species ecology, pollinator health, and insect pest control. He holds a Bachelor’s degree in Entomology from Cornell University and a Ph.D. in Entomology from the University of Maryland. Dr. Ramsey’s research on bees has enabled researchers to develop targeted control techniques to restore honey bee populations worldwide. He also hosts a YouTube series called “Dr. Buggs.”

Samuel Ramsey, PhD

Entomologist

Expert Answer

Woolly bear caterpillars go into a state of dormancy during the winter. They enter their cocoons at that time.

Warnings

Caterpillars will turn to cannibalism if not given enough plant material to eat. Caterpillars will also kill and eat other species such as a moth, or another variety of butterfly.

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