I believe the larger caterpillars may eat the hatchlings..

They are not larger cats. They are in chrysalises. Can I put tiny cats in with chrysalises?

In that case, I don't see any problems as long as there is milkweed for your cats.

Paul, Do you think I can put my BST cats across the cage from little monarchs in the same cage? I think if I can get them all well started, I can move the 17 currently tiny monarch cats into the huge fine mesh cage once they have been through several instars and keep the BST in with the chrysalises. Right now, the huge cage is too much to manage tiny cats in. I have three sizes of cages. The best one to me is 14 x 14 x 24" tall. Thanks for your help!

I'd keep the tiny Monarchs all in a single plastic food storage container without even putting holes for air. As long as you open the container once or twice daily, they'll have plenty of oxygen for their needs. And you'll need to open it to put fresh leaves in and clean out the fras at least once daily.

Martha

I'd probably do what Martha suggested. You can also put them in with the chrysalides. The thing to consider there is that when the caterpillars are larger and eating a lot it might coincide with eclosure of the ones in the chrysalides.

Make sure you have plenty of food--a day's worth or so when you expect the butterflies to come out. That way you won't disturb a butterfly that is drying its wings, etc.

Another three monarch cats died overnight. I moved them to Gladware storage tubs. I feel terrible. I am trying to learn to be a better Mom. Meanwhile, three of my Luna moth eggs hatched! The only host tree I have on this property is Black Walnut. I placed three young leaves in the container but I do not see them eating at all. I tore the leaves as Bill suggested. I have tried to find other host trees on the list but they are all on private property. If the Lunas only have Black Walnut will they eventually eat it?

Yes they will
Jacob

Update: After placing all cats in Gladware, none have died. Thanks, Martha! So now I have 14 Monarch cats on Common Milkweed and 2 BST on Parsley plus a herd of Luna cats which just hatched and are eating the Black Walnut (Thanks, Jacob!). I will get a count on them tonight. Wow, they are tiny! The 7 Monarch chrysalises are a long way from hatching but I can't wait. I will try to post some pics tomorrow. Thanks!