It could be that your plants had chemicals on them. This would cause small cats to get sick and eventually die. I live in FL, and when winter comes, I just leave my chrysalids on a covered patio where they will stay cold. They emerge when warm weather comes, usually about Apr. or May. Don't ever get plants from any of the big box stores either since they are all sprayed. Sometimes even ones from nurseries are also. You did right to bring them in. I know others will be commenting. Just leave the ones that are lethargic alone to be sure they aren't just in a changing stage though. Good luck and welcome to the wonderful family of butterfly parents.

There are many possible reasons why the 9 cats disappeared. Several or all of them may have died as hatchlings - when a cat dies naturally, it'll usually happen when it's a hatchling or a very early instar caterpillar. Ideal temperatures for caterpillars are higher than the 70's, so the lethargy of your cats could be from that or, more likely, the low humidity. Air conditioning and heating both lower the humidity in your house to a level that is bad for cats, at least our southeastern ones, who are adapted to high humidity. I've never had much success rearing mine in the house in what I thought were perfect conditions, so mine stay on the porch in a sheltered situation with ceiling fans blowing if needed, no direct sunshine, but with all the natural heat and humidity. I read somewhere that eastern big moth cats don't do well in the low humidity out west - it has something to do with their ability to take in air through their spiracles. So I imagine that eastern butterfly cats breathe better in higher humidity, too.
Another possible cause is the parsley itself - it wouldn't have insecticides on it, would it? That would be deadly!
I raise my cats in butterfly cages - they're made of a simple PVS frame covered with mesh - they have a zipper for easy access. I also use florist's water picks and/or leftovers containers filled with water, with a hole cut in their top just big enough for the host plant material.
Good luck!
MissSherry

Hi! Thanks for the info on the black swallotail cat. I have lost 4 more cats and have 2 large ones that are rolling around on the floor of the cage and the dirt of the parsley plant. Is this normal behavior or are they sick and slowly dying? I have not been able to find any organic parsley so they have been eating the parsley I got at Lowes. Also, I have a parsley plant outside that I bought from Lowes at the begining of the summer it was cut and has come back, now there are more BST eggs and 2 new cats on it. Should I leave them on this plant and keep them outside or bring them in before it gets too cold? Thanks for the help, these little guys are really stressing me out! I want to make sure I am doing the right things for them so they will survive!

Hi! I am new to the forum, but I have raised lots of black swallowtails. That behavior does not sound normal. It sounds like the parsley may have insecticides on it. I have bought parsley at the grocery store and washed it well when the cats had nibbled the parsley I had to the bone. I wish you all the best!

Hi swallowtailgirl! I am new to the forum also and it has been very helpful. I didn't think the rolling around behavior was normal,I think it was my parsley plants. They are Bonnie brand plants and the cats were eating them up and they seemed fine and kept getting bigger and bigger but then they slowly started dying off and since my last post sadly the 2 I spoke of have died:( On a happier note I have about 8 more newly hatched ones on a parsley plant I have on my deck. I am going to Whole Foods to get organic parsley, I am not taking any more chances with the other plants. I live in the Atlanta area and I am wondering if I should leave them outside covered with screening material or should I bring them in? I am assuming that they will not survive if they emerge from a chrysallis as a butterfly. I have a large aquarium I can keep them in for the winter. Thanks for your help or anyone else that can help me to sucessfully raise this batch of BST babies!:)

Is there a particular reason that you don't want to feed them on cuttings from the parsley you have already growing on your deck?

I'd be afraid that even the organic parsley may have been sprayed with an organically certified pesticide such as bT which would kill the cats.

I feed my BSTs carrot tops from my garden. I raised over 50 and never ran out of food as the carrots produce a lot of greens.

Maryann in CT

Hi Maryann in CT. The parsley on my deck is Bonnie brand from Lowes. This is the same plant the first batch of cats ate. They ate it down to nothing and it has come back and has newly hatched cats on it. I went out and got organic parsley. All the parsley plants I had before were the same brand and all of my caterpillars died. I don't use any chemicals in my garden. They got so big and looked so healthy but then they just started dying off. One did make it to a chrysalisbut when it emerged it failed to get all the way out of the shell and could not inflate it's wings which was very sad to watch. I wonder what they are spraying the plants with and if it is killing the caterpillars what is it doing to us? I hope these cats will be ok with this new parsley. My other problem is I don't know if I should leave the new cats in a covered container outside or bring them inside to an old aquarium I have. I have some screening material over them now to protect them from predators like praying mantis, lizards and spiders. I assume they wil have to wait until the spring to emerge as butterflies so I will have to keep them somewhere cool, correct? Any suggestions and advice will be a great help:) Thanks!