If they are healthy, the cats will pupate, and hang as chrysalids. They will develop into butterflies in about 9 days, if they are kept at 80 degrees F, approximately. This would give them a jump on the long flight south, to Mexico. If the weather cools, to 60's and 70's, then the chrysalids might require 12 or even 14 days to mature into butterflies. With regard to your potted tropical milkweed, most people consider this plant to be an annual, north of the Mason-Dixon line. It might be best to start over with a new plant, come next spring.

To increase their odds of making it to butterfly-hood, you can bring the cats inside in a container, feed them your tropical milkweed until they stop eating, and let them pupate there. And then watch them eclose and release them, which is very fun. If you leave them outside, and they survive, they will wander off to pupate somewhere and you may not find them. The big cats and chrysalises are still vulnerable to predators and disease (although they occasionally have problems inside too).

Thank you ericwi and terrene!

What kind of container should I use if I bring them inside? Something made out of mesh or a plastic container with holes punched in the lid?

Brad AKA Moonwolf

I hand-rear monarch cats using an individual one quart glass mason jar, covered with a small piece of fiberglass screen material, held on with a rubber band. One caterpillar per jar. This is done to keep them healthy-if one gets sick, the infection is limited to only one caterpillar.

I use plain, plastic food-storage containers, and I don't even put holes in them. If there is only one caterpillar in a container, they have enough air to survive. I do open and check/clean the containers twice daily, so they get fresh air. As they get bigger, I tape a piece of brown paper bag to the inside of the container top. Then, when they pupate, I can move them--still attached to their paper-- to a larger area to wait for ecloser.

Martha

Thank you again, ericwi and Martha!

I have some Mason jars but no screen for on top of them. I'm going to ask mom if she has any old plastic food storage containers that I'll be able to use.

Brad AKA Moonwolf

Brad,

I raise caterpillars in paper sacks. I put about 4 in a lunch sack and throw in food. It's easy to clean--just dump out, and the caterpillars pupate on the sides of the sacks. Someone questioned if they get enough light. I put the sacks on my east facing windowsill. You can hear them eating, and when they eclose, you will hear them too. I've raised hundreds this way. Be sure to secure the sack when you fold down the top. I use either clothespins or paperclips.

Sandy

I use clear plastic boxes that had salad mix in them, they are about the size of a small shoe box. They have holes in the tops and bottom. I originally saved and prepared these containers for winter-sowing, but found that they worked even better for caterpillars.

When they are ready to pupate, I tape paper towel to the underside of the top and the cats pupate there. Then, once they have pupated for 24 hours (for the chrysalis to harden) I move them on the paper towel to a 10 gallon aquarium, where they will eclose.

The fiberglass screen material that I use for hand-rearing monarch cats is what you can buy at a hardware store to replace a damaged window screen. It has a grey coating, and it can be easily cut with scissors. I don't think that it's very expensive.

I use plastic containers. I cut the inner portion of the lids, making sure not to get too close to the outer area so that they'll still snap on. I purchase packets of tulle from the dollar store and use those to cover. The cat generally pupates on it, even though I had my first this year pupate on the side of the container.
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