The size of the container depends on the number of caterpillars that you will have living in the container. As a general rule, each caterpillar should have at least three times their body size in extra floor space. A container for 10 6cm long caterpillars should be at least 25x25cm of floor space. Caterpillars don’t tend to move around that much, but every caterpillar should be able to feed without coming into contact with the others. [2] X Research source Although you can raise a bunch of them together, it’s important that you don’t end up with a cage so full of caterpillars, or they might crowd each other out and not get enough food.

To make the habitat a little more humid, you can place a moistened paper towel inside the container. [3] X Research source Don’t add any open water into the container, as a caterpillar can easily fall in and drown. [4] X Research source

Some common host plants include Aster, Hollyhock, Sunflower, Snapdragon, and Violet. [5] X Research source If you know the details about your caterpillar, you can search for host plants via the website of London’s Natural History Museum. Caterpillars will typically get most of their moisture from these plants, but you can wash the leaves with clean water to leave some extra moisture for them. You can add individual twigs and leaves, or a potted plant. If you add a potted plant, make sure it is kept watered, but also make sure that there is no standing water that could potentially be a drowning hazard. [6] X Research source

Heating in the winter and air conditioning in the summer may also dry out the atmosphere and potentially harm your caterpillars. You can keep them in an unheated place, such as a garage, or introduce more moisture to their environment by placing a moist paper towel in the container. [8] X Research source

In a closed container, you should be checking and cleaning out frass every day. [9] X Research source You may want to place some tissue paper or a paper towel on the bottom of the container to help catch and absorb frass. You should still change this paper daily. [10] X Research source A more well-ventilated container could be cleaned of frass once a week. It’s important to monitor it closely and react accordingly. [11] X Research source

If you have a clear container, this will make it easier for you to observe the caterpillars. Make sure it’s clean, but doesn’t have any lingering cleaning substances on the surfaces.

If you are adding a whole plant, make sure the plant is healthy and will continue to thrive and grow. A plant will still need light to photosynthesis and remain healthy and a good food source for the caterpillars.

You will struggle to completely eliminate the danger of predators and especially parasites and parasitoids. [13] X Research source Regularly cleaning away frass can help, as spiders are drawn to the smell. [14] X Research source

You can always add some extra things, such as pebbles or more greenery. Remember that once your caterpillar has found a good place to eat, he won’t be too interested in exploring. Try to avoid handling the caterpillars as much as possible. If you do need to handle them make sure your hands are clean, and ensure that you have rinsed off any excess soap. [15] X Research source

When it is ready to pupate, the caterpillar may move away from the host plant. Remaining near the host plant can make it especially vulnerable to predators, so he may look for an unusual spot. He will find a place to attach himself to form a cocoon, or, in the case of some species, he will dig into the ground and pupate there. [17] X Research source

For most butterfly species you should supply a vertical surface, such as a twig. For moths, you should give them some leaf litter or loose soil. [18] X Research source

If the pupae is on a stick that you can move, try to carefully move it to a more open space in the container. You might be able to make more space by removing other leaves and twigs while leaving the cocoon itself untouched. If you have to move a cocoon, moisten the silk that attaches it to the surface and very carefully pull it free. [20] X Research source Be sure you keep it the right way up and attach it to a string or stick that has more room. You can use a straight pin to attach it, or some glue that is warm and tacky but not hot.

Most caterpillars will stay in their cocoon over the winter, so if they pupate in the fall, they will likely remain in there for months. He could, however, only be in his cocoon for a matter of days before emerging, so it’s important to pay attention. Remember that throughout this time they are still alive and still require some care. An occasionally misting of the container with water, or the addition of a wet paper towel will help provide the moisture he needs. [21] X Research source

The butterfly will fly when he is ready, and then you have to choose whether to keep him, or release him into the wild. You should only release him if he is a native to your country. [23] X Research source