When your enclosure is ready (click here for advice if needed), place it in a protected area outdoors out of direct sunlight (this is why), and now you can add your caterpillars!
If your caterpillar is an egg or new baby less than a half inch long, you should either (1) put it in a small cup with a lid, or (2) let it stay outside until it gets bigger. There are reasons for and against either option; I really can’t tell you what is right for your situation.
1) If you bring in eggs/babies, you’re committing to about a month of care (half of which it will be in a chrysalis though). You’ll need some supplies: cup/lid for babies, preferably a mesh enclosure for the larger caterpillars, and plenty of milkweed. You may discover online that monarch caterpillars can eat some human foods like cantaloupe, but please do not think that it means you don’t need to bother finding sufficient milkweed. I can’t stress this enough: human food should only be given in the case of an emergency, and only to the largest caterpillars that are just about to pupate. Baby and young caterpillars must have milkweed to develop properly.
2) Leaving cats in your garden until they get bigger alleviates some of the work on your part… They won’t need the cup with lid, just a mesh enclosure. But you run the risk of something going wrong, such as getting parasitized, contracting a disease, or just disappearing.
There is a sweet spot between the two options which is where I aim to bring them in. Whatever you choose, try to keep them separated roughly by age. That is, little ones together and the big ones together. The big ones can eat the smallest by mistake!
Don’t touch or handle the caterpillars unless absolutely necessary. Caterpillars are extremely sensitive to chemicals, including soaps, lotions, and (nowadays) hand sanitizer. It will need the leaf it’s eating anyway, so just snip it and transfer the whole shebang into its new home. For eggs/babies, just part of the leaf is sufficient.
Caterpillars molt a total of four times over the course of about 10-12 days before they pupate. When the caterpillar is roughly the size of an average adult woman’s pinky finger, it’s probably a day or two away, maybe only hours. If it’s closer to the size of a child’s pinky finger, you’ve probably got at least a week, give or take. Click here for my post with some very approximate time tables for each stage.
The amount of milkweed that you will need depends on the size of your caterpillar and what variety of milkweed you have. Common milkweed leaves are very large, so just one will be fine (freshened daily until your cat pupates). But swamp milkweed, butterfly, and tropical all have a much thinner leaf, so you’ll need a couple at a time for all but the smallest babies. There are many other varieties, so here’s a rough estimate: if the leaf is about the width of your palm, that’s plenty to start. If it’s the width of a finger or two, start with 2-4 leaves. Check your caterpillar frequently, clean out the poop, and make sure it doesn’t run out of milkweed. Also keep tabs on your enclosure and watch that it does not get condensation on the inside (which is why mesh is preferable).
If you want a more precise estimate of your caterpillar’s age (and therefore a better understanding of how long it will be before it pupates), here’s a great video: Identifying what instar by Mr Lund Science. He has a whole series on monarchs and they’re all excellent.
If your caterpillar is a baby, it will molt four times before it pupates. That means medium-sized cats, say around an inch long, have probably already molted twice. When they molt, they crawl off the leaf and hold very still. Do not disturb a caterpillar that is molting! They eat the shredded skin and go back to their leaves when they’re done. It could hold still for more than a day.
When your caterpillar is ready to pupate it will crawl up/away and hold still just like it did while molting. Or at least it seems to be holding still, but it’s actually spinning a pad of silk which it will use to anchor the chrysalis. When the silk “button” is ready, it will hang upside down in a J-shape. Again, do not disturb it at any time during this process, which will take a day or so, just like molting.
The caterpillar is just about to pupate when its antennae look droopy and wilted. It happens fast… Like when you turn your back for a moment! The chrysalis will harden and turn jade green over the next day.
>Side note, I think sometimes when they’re in captivity they get confused, because you might have a caterpillar go into a J-shape on a leaf. This is not ideal, but you do not want to disturb it. After it pupates, wait 24 hours before doing anything. Unless you think it might fall, in which case you should lay the J-shaped caterpillar on a napkin on the ground (they can pupate laying flat like that). If the fresh chrysalis is on the ground, turn it over a couple times until it hardens, then just leave it be. You do not need to try and hang the chrysalis.
Once all your caterpillars have pupated or at least gone into a J-shape you are done with the milkweed. If you can, remove the leaves, but only if you can do so without bothering the caterpillar (unless of course you have more than one and they’re still eating). Do not remove your sticks though.
If a chrysalis turns brown, unfortunately it didn’t make it. There’s a lot that can go wrong, none of which is your fault. Although it doesn’t hurt to wait and see, if it has been more than 2 weeks and the color is off (brown or yellow), then you can be pretty confident it is dead. Wild caterpillars only have about a 5 percent survival rate, and it’s possible that it was diseased or infected by a parasite before you even found it.
After a week or so, give or take, a healthy chrysalis will seem to turn black. Technically the chrysalis is actually clear and what you’re seeing are the black parts of the butterfly inside. Your butterfly will be emerging within a day.
Once it comes out, it will look wrinkled and strange, with the wings too small and the body too big. You may see drips of a reddish fluid, which is normal, although we really don’t want that fluid falling to caterpillars and their food below it if it can be helped. For this reason, if you are raising a lot of caterpillars of mixed ages you’ll want to plan on at least two enclosures.
The butterfly will hang and the fluid in its abdomen will pump into the wings and fill them out. I have a time-lapse video in this post that took place over the course of about 10 minutes and you can actually see the wings filling up! It should not take more than 20 minutes or so to look like a normal butterfly, and it’s wings will continue to dry and harden over the next 2 to 4 hours.
If it’s been a lot longer than 20 minutes and it’s still wrinkled, if it falls repeatedly, or if it falls and can’t get back up, it is probably diseased (not your fault). A healthy butterfly can lose its grip and fall, but it will immediately climb back up and keep a better hold. This is why you left the sticks in the enclosure, or placed a loose chrysalis near the side.
You should keep your friend for 24 hours and then let it go once the day warms up. Healthy butterflies do not eat for the first 24 hours, so no need to worry about providing food such as sugar water unless extreme circumstances require you to keep it longer. Please do not give Gatorade or other sugary drinks.
Their instinct is to fly away from their chrysalis to a quiet tree to allow their wings to get strong, so it might flutter around your enclosure. It’s easy to think, “S/he wants out! S/he’s ready!” However, this is a very vulnerable time for them, so do your butterfly a favor and keep them safe. Putting your enclosure in the shade or draping a towel over the it may help calm it down.
Are you hooked yet?
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