So sorry to hear that your babies are dying. Have you disinfected your tank recently? After each group of cats pupate and eclose, I always put my cages through a soak of mild bleach water and then rinse really well. And put in the sun to dry if at all possible (sunlight helps to dissipate the bleach).

I try to keep the number of cats to about 10 per enclosure, haven't had to worry about that this year, the drought is keeping the butterflies away, at least I hope that is why they have been absent.

I would wait and see what happens with the cats, if there is a chance that the pupas will be okay, you don't want to euthanize. Good luck.

Mechelle

Sorry about your catepillars.

I have lost about 30 catepillars out of 300 so far to either parasites or that black liquid you described. I have been cleaning the containers that I have been keeping them in with weak bleach solution.

I would wait too, to see what happens

I would like to know as well. I lost both of mine the same way. I was careful on the sterilization/cleanliness as well. It seemed to me that it seemed to happen when they molted (?)...Like their new skin ruptured or something. I know from my Boa Constrictor that if the humidity is too low, they will have trouble getting the sloughing off the old skin.

Could the old skin be sticking and rupturing the new skin?

How do you handle your humidity?
I'll assume if you have potted plants or some sort of moistened substrate for the leaves you'd probably not notice, but my Bottle and stopper method doesn't allow for evaporation. ("Hmmm..." the mad scientist says as he strokes his chin and gazes off into the distance...)

Any Thoughts?

There are so many things it could be. It could be a bacterial infection. It could be failure to molt properly. In addition, when caterpillars molt between instars, and when they pupate, their skin is very soft and easily ruptured. If another caterpillar walks across the molting/pupating caterpillar, it can rupture the skin. Commercial and research facilities will actually keep monarchs in individual containers for this reason, as well as to prevent cross contamination.

Cleaning the containers thoroughly and keeping numbers low per container should help. Stress on caterpillars can lead to disease. Overcrowding, lack of food, low or high humidity can put additional stress on caterpillars.

Good luck,
Elisabeth

Well, that didn't end well at all. The last few cats did not pupate properly and I noticed a couple tiny black spots on the original two crysalids that appeared at first to be healthy. I put all the crysalids in the freezer to euthanize. :(

Here's my plan moving forward. I am going to put all my caterpillar gear in the dishwasher on "sani-rinse", then I am going to bleach soak everything in the sink. I will use bleach wipes on the whole area where I keep the containers because I'm sure I could have touched things after touching the sick cats container. Then I will start over. Just a few eggs, one per container, to see if I can get healthy butterflies.

Soooo disappointing and I hope it doesn't indicate what the rest of the season is going to be like. I have never had this level of problem before. I've always been careful to keep everything clean and fresh and not overcrowded.

I DO have a container with 6 (seemingly) healthy BST crysalids and another with three BST cats, so that perks me up a bit.

I am now raising monarchs in one quart glass jars, the kind that is used for canning vegetables and fruit. The top of the jar is covered with a piece of fiberglass screen material, held on with a rubber band. The jars are cleaned and dried daily, or more often as necessary. Also, I am hand washing milkweed leaves under a stream of cold water, and drying the leaves with a paper towel, before they are fed to the monarch cats. There is only one caterpillar per jar, so cross-contamination is minimized. I typically raise and release 10 monarchs per season, so the extra effort required is not overwhelming. I can't say that these measures eliminate disease issues, but they do seem to improve the odds of success.

I have had the same issues with my monarchs. I have been keeping the first couple of in-stars in cages then in the last in-stars I put them outside on the plants. I also think Not moving them when they are molting is VERY important. i have had more success with doing this.