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monarch cats dying and one failed pupation...

Posted by sitali301 6 (My Page) on
Fri, Jun 24, 11 at 19:26

Hi, I don't most much (maybe once or twice a year) but I'm hoping you guys can shed some light on my situation. I have raised monarchs every summer for the past several years and have almost always had good luck. The few sick cats/butterflies I have experienced are usually late in the summer.

I have a tank at the moment with 6 monarchs. I collected a total of 10 eggs over the period of several days in my own milkweed patch. Four cats died around the second instar stage. Two have pupated and the chrysalids appear healthy (no black spots). One went to the top today, made a J and several hours later I noticed green ooze at the top of the cat and black liquid that had been emitted and run down the side of the tank. The other three are 5th instar and should be heading up to make their "J" any time now.

Clearly, there is an issue, but I'm not sure what to do. Should I see what happens with the cats that don't appear sick or should I euthanize all of them since clearly they have all been exposed to whatever illness is in there?

As much as I don't want to euthanize possibly healthy cats/chrysalids, I even more so do not want to release sick butterflies that may *appear* healthy when they eclose.

I'm worried that the FIRST batch of monarchs are sick... what does this foretell about the rest of the season and the health of my milkweed??

Follow-Up Postings:

RE: monarch cats dying and one failed pupation...

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.


RE: monarch cats dying and one failed pupation...

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

RE: monarch cats dying and one failed pupation...

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?

RE: monarch cats dying and one failed pupation...

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,

RE: monarch cats dying and one failed pupation...

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.

RE: monarch cats dying and one failed pupation...

  • Posted by ericwi Dane County WI (My Page) on
    Sun, Jun 26, 11 at 20:26

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.

RE: monarch cats dying and one failed pupation...

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.

RE: monarch cats dying and one failed pupation...

beccalmt- I've moved MANY MANY molting monarchs and never lost one from it. I've lost a couple black swallowtails that way though, so I only handle them when absolutely necessary.

In raising monarchs over 30 years I have never has a disease outbreak. Part of it is my location. In Minnesota all the milkweed dies to the ground each season so most of the OE spores are killed. These are the things I do to care for my monarchs...maybe something will strike a chord with somebody:

I usually give them leaves twice a day...once early, once before sundown

Each time I rinse the leaves in the sink in cold water(have never used any sort of cleaning solution)

I also empty the cage of frass before adding new leaves and then rinse it out with warm water...then DRY it!

I handle my monarchs a lot, taking them off old leaves and placing them on the new. If they are 1-3 days old I tear off the section of leaf they're on and place it on a new leaf.

If using my large caterpillar castle, I take a warm rag and clean off the floor each time I change leaves. (since I can't rinse it out in the sink...the material dries fast)

I usually try to limit my cage to 10 cats....I would separate them if there were signs of an outbreak.

Minrose, have you had disease problems in Minnesota before? What is your routine?

Sorry to hear some of you are having problems. I hope you all have some healthy monarchs soon! Tony

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