Hmmmm........when cats are very active, assuming they're not last instar looking to pupate/make a cocoon or burrow, it's usually because they're searching for food. I imagine these were just a bad batch of eggs, whose cats had something wrong with them that you didn't cause. That happens sometimes.

But in case you raise some in the future, here are the host plants that David Wagner lists in his book - "basswood, birch, cedar, elm, maple, oak, pine, sassafras, sweet gum, sycamore, walnut, and other woody species."

I've never raised any myself, so I don't know what their local host plant is. Somebody brought me huge caterpillar once, obviously looking to burrow/make its pupa, but I don't know what it ate. It looked like a hairy pickle! :)

Sherry

If you ever have any extra eggs/caterpillars to share, I'd love to have some to raise and to educate people about these incredible animals. I'm in the Chicago area too.

Sorry about your Imperials. KC Clark may have some input.

My opinion is the cats just did not like the leaves/needles offered to them. Maybe the needles were fir or spruce and not pine. As for the leaves, it could be a regional difference as to why the caterpillars refused the food.

I have a lot of imperials this year so I'm trying things I've not tried before. I went out earlier tonight and looked at the imperials I put on hickory and chokecherry. No frass and dead caterpillars. Both are supposedly imperial hostplants but did not work for me. Their siblings are doing fine on sweetgum, eastern white pine, and Norway maple, all hostplants I've used in the past.

I had more hatch today so I put some on walnut to see if it works for me.

Very sorry to read about your troubles with imperials. The first one I found broke my heart when it refused to eat anything but the pine I found it on. On the first night I had it, it ate every needle I had collected for it. Begged my mom to take us back to get more from the tree but she said I could get other food for it when we got home (were staying about 2.5 hours from home). When we got home, I gave it every type of needle I could find (plus various leaves) but it chose to starve instead of switch. :(

How long after the eggs start to turn brown do they hatch? This morning the cluster of eggs that were laid first are all turning dark. The cluster that were laid one day later are still yellow. Do you think it will be today, or can it take longer?

Cathy

They actually are not turning brown. The eggs are now clear and you are seeing the caterpillar inside.

I have not paid close attention to the timetable between the eggs turning clear and the eggs hatching. I'd say the cats will be out tomorrow.

Only one of the imperials I put on walnut is producing frass.

The cats on chokecherry are doing nothing.

Some years ago, my big idea was to plant fast growing trees that could act as hostplants for the main cats I raise (cecropia, luna, polyphemus, regal, and imperial). I came up with chokecherry and staghorn sumac. Deer have kept "fast growing" from becoming a reality. Now I find out the imperials won't eat the chokecherry. Good to find it out before I needed to use it.

The chokecherry finally got big enough to use last year. Raised cecropias and prometheas on it. Not happening this year. Cardinals have been a pain. They pecked to death all the caterpillars I had out there. They have also been playing havoc with the prometheas I have on spicebush. They were killing many of my lunas on sweetgum but I started bringing in the lunas when they got to third instar. Unfortunately, I don't have room to bring in everybody.