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Raising Caterpillars

I often get questions about how to raise caterpillars. One of my first jobs during college was raising caterpillars, which lead to similar jobs throughout the years. Why raise a caterpillar? Not only does successfully taking care of another living thing lead to insights into its biology and behavior, but also when a beautiful butterfly or moth emerges, it is an amazing experience.

A few weeks ago I wrote a post about white-lined sphinx moth caterpillars.

whiteline caterpillar

In the update I mentioned that I had placed a caterpillar in a terrarium with moist potting soil (about five inches deep). The caterpillar immediately disappeared, but I knew where it had gone. Large moth caterpillars, like white-lined sphinx moth caterpillars or tomato hornworms, dig into the soil before pupating. Their pupa looks like a dark reddish-brown cigar. Saturday I found the moth sitting on the cloth I had used to cover the terrarium. It had successfully emerged.

Here it is.

whitelined sphinx mothwhitelined sphinx moth

Because white-lined sphinx moths are big and active, they need a lot of nectar to keep them going. After taking a few pictures, I immediately let it go. Here’s a link with some amazing pictures of white-lined sphinx moths. This entire website is full of great information and photographs.

What do you need to raise caterpillars? It does depend on what kind, but here are some general guidelines.

1. Unless you are using a kit that supplies special food, you will need large quantities of fresh plants. And not just any plant, most caterpillars will only take one or a few kinds of plants as food. Once a tiny larva has started eating one kind of plant, they often will refuse to take anything else, even if other members of its species will. A good rule of thumb is only bring home caterpillars that you are absolutely sure you know what they eat, and you have lots of those plants available to feed them. Edit: What white-lined sphinx moth caterpillars eat.

2. Provide a clean, safe container covered with screen or cloth to allow for air circulation. It is best to keep the container outside in as natural conditions as possible. Insect life cycles are extremely sensitive to light and temperature. If you bring the critter inside where it is cool and dark, it may emerge days or even weeks after wild members of its kind and may miss critical windows of opportunity to perform necessary behaviors like mate or migrate.

3. Keep only one or a few in a container. Crowding insects into small containers greatly increases the chances for disease. Insects can get viruses, bacteria and fungi, which can make them sick, just like those things can make humans sick.

Scientists have suggested that monarch butterflies may migrate because of a parasitic infection. This parasite (a protozoan) causes the butterfly to be weak but not die. By going on long migrations, the sick individuals are left behind. When we handle monarchs, we risk spreading the disease even more. Let me know if you’d like more information about this.

4. Provide sticks for butterfly caterpillars to climb on when they are about to make their chrysalises. Moth caterpillars will need plenty of moist soil to dig into. Other caterpillars may like to have different substrates to pupate in, like cloth or egg cartons.

5. Insects are also sensitive to humidity, especially when they are molting. It can be tricky, but try to keep the humidity up without getting the container too moist. Too much humidity can cause things to get moldy.

I hope these guidelines doesn’t sound too negative. Having a lot of experience, I have a better idea of all the things that can go wrong and I wanted you to avoid the problems. And oh yes  here's one more:  don't leave the lid off the container once the caterpillars have pupated. My son did this, and we had cabbage-looper moths all over the house. (It was actually a hoot!)

One great way to raise caterpillars is to plant butterfly and moth plants in a butterfly garden. (Check out an earlier post on butterfly gardening.) Then the caterpillars do all the work themselves.

Also, don't forget to take a look at some of the butterfly and caterpillars books for children.

And finally, my friend Debbie called again. Her passion vine plants now have gulf fritillary caterpillars on them (see last week’s post for details).
gulf fritillary caterpillar

177 thoughts on “Raising Caterpillars

  1. Nancy

    Hi Roberta! Found this site while researching. We've kinda let our backyard go recently (Tucson, AZ), but it has apparently produced a perfect place for at least 25+ white-lined sphinx caterpillars. They're glorious! I know they burrow and our normal soil is the hard, clay like type. I'd like to provide an area for them to avoid them wandering for a spot and getting harmed in the process. How should I go about this? Thank you so much for your expertise!

  2. Roberta

    Nancy,

    Congratulations on having the white-lined caterpillars in your yard.

    I fully understand the soil type, but the caterpillars will probably do just fine. If you want to try something, scratch up small patch in an out of the way location and add a little compost.

    Enjoy!

  3. Nancy

    Thank you! And you're right. I already see some holes and fewer caterpillars. I loosened up a little section anyway, just in case.

    Thanks again!

  4. Patti

    We found a caterpillar and gave it a habitat in a cleaned fish bowl with about 5 in of soil. We watched it dig and dig, and can see what appears to be a protective "netting" attached to a couple sticks, dried leaves, and the soil; the bowl has been coveted with an upside down colander. Nothing has emerged and it's been several weeks. Would it help to place it outside? Any other suggestions?

  5. Roberta

    Hi Patti,

    As long as the soil stays slightly moist, it should be okay. Sometimes these things can take months. Can you set it outside somewhere where it is protected, especially from direct sunlight, yet you'll still remember to check it? Otherwise, it will probably be okay.

  6. David

    I found this Pandora Sphinx Moth caterpillar on my grapes. It is Aug 27th and a Frost is possible at this latitude ( NW Wisconsin) In two weeks. I would like to capture it and watch it pupate but I fear that it will emerge when it is to cold for it to survive. Any suggestions on how to do this would be welcome. David

  7. Roberta

    Sorry if this answer is late. The best strategy might be to keep it under natural conditions. That way it will enter hibernation for the winter. Do you have a garage or shed that is unheated?

  8. jarren

    I'm needing big time help!! If we don't have dirt that is safe. What else can I use? It seemed to attach linging of some sort all they way around her/him all the way a flower and side of a container while it's laying on paper towels I hate to move her. Now today she shed all her skin she don't seem to even have her legs anymore she likes to be on her back and then awhile later she will be back on her tummy I see the colors changing by the min a few white hairs coming out of her.. I read a cut up soft blanket would work or ripped up paper towels. Is this true this is the most beautiful thing I've seen since the birth of my own children! I need help I hope you see this post!

  9. Roberta

    Is she dark brown yet? If so, then she probably pupated successfully. Now try to keep it in a place that is humid so it doesn't dry out too much.

    Good luck.

  10. Sam

    Hello,
    My dog brought in a sphinx moth Caterpillar and it seems to have an injury under its horn. I dont know really what I should do. I would prefer it didnt die but I have no idea how to help? Normally when I find them I relocate them to the front yard around similar plants but I dont know how it will fair with its injury?

  11. Roberta

    Insects do have some capacity to survive wounds, especially if it is close to a molt. Your idea of putting it outside near food plants is probably the best one.

  12. Kadence Santos

    I have had a chrysalis for around a month now and I’m wondering how I can speed up the pace. I’d like it to emerge soon, I know it’s alive. I also have a hickory horned devil and of you could provide any advice on caring for it that would be great, I saved him from drowning and he’s about 3-4 inches long and quite fat.

  13. Roberta

    The hickory horned devil should turn a turquoise color right before it is ready to pupate. It also pupates deep in soil, even deeper than sphinx moths, so you'll need to give it a big terrarium with about six inches of soil in it.

    Do you know what species the chrysalis is? Some butterflies overwinter in different stages. If it overwinters as a chrysalis, it may need a cool or cold period before the adult will emerge. Otherwise, warming it up to temperatures that mimic warm days where you are might make it develop more rapidly.

  14. Veronika

    I found a leopard moth caterpillar crawling through the grass in my front yard and brought it inside to try to keep as a pet. We are in Georgia so right now temps are 40s - 70s. I’m betting it will hibernate, does it need to be outside? I’m so scared of spiders/bugs somehow getting into its habitat and eating it! Also I haven’t seen it eat anything yet (we’ve had it for going on three days), and sometimes it doesn’t move for a verrry long time. And do you know how deep the soil needs to be? And do I need to spray the dirt with water every so often? And how do I clean the frass if it’s on dirt? Sorry so many questions!!

  15. Veronika

    Ok I’m not sure why I didn’t read through all the comments first! They helped a lot — now for my new questions 🙂 Should I add a cardboard box to the plastic box the caterpillar is in now if I don’t want it to pupate now (due to the cold)? And do you know if they hibernate in the dirt or just under leaves and grass?

  16. Veronika

    Ok one more question! All he’s doing tonight, which is the most I’ve ever seen him move, is crawling around the perimeter, making a trail in the dirt, and trying to crawl up the sides to escape (12”x20”x8” high). But he stretches up as far as he can and then falls over because he can’t climb the plastic. Does this mean I should let him go? I’m so scared of him dying!

  17. Roberta

    He's in the wandering phase, which is normal. Is the dirt soft and moist? If the conditions are right, he should dig in soon.

  18. Veronika

    How moist should it be? If I just spray the top of the dirt is that enough or do I need to saturate it more so it spreads to the under layers of dirt too? I did put some cardboard in there and he likes it, and he sometimes burrows into the grass but I haven’t noticed him eat any. I added some basil and lettuce today and still no eating...and I asked about violets and lilacs at Home Depot and they didn’t have any/aren’t in season. Thank you for responding!

  19. Faz

    A moth laid it's eggs on the wall and they just hatched (it's winter). I found them today and some are moving and some aren't.
    What should I do with them??

  20. Roberta

    Oh no. You don't have any idea what kind of moth laid the eggs? Because that is the best way to figure out what the caterpillars might eat.

    Given the circumstances, you could try putting them with some lettuce and carrot peelings, which sometimes can serve as emergency foods for a number of species. Good luck.

  21. Veronika

    Hi! I just wanted to give you an update - - my leopard moth caterpillar spent a few weeks making a shallow bowl-like hole in the dirt, completely underneath a thin soda can style cardboard box. I lifted it up today to check on him and he started spinning silk or whatever it is he does, so I won’t be checking on him anymore. Do you think there’s any chance he’ll stay in there all winter? He’s inside my house because I’m scared to put him outside, and he hasn’t shed any of his bristles yet.

  22. Roberta

    I'd put him in the coolest place indoors you can find and let nature take its course. Keep checking, in case he pupates and comes out early.

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