Hi Jeff;
Sorry about your caterpillars. First, can you describe some more symptoms. Do they smell? That first picture looks very much like a NPV (nuclear polyhedrosis virus). These take approximately 1-2 days to kill. Very quick and the caterpillar turns to goo. If it is NPV, you need to take quick action. NPV is highly infectious. Make sure to sanitize anything that came in contact with a strong bleach solution. So far my experience with bacterial infections is that they are not that fast. The caterpillar does turn black but does not turn to goo overnight.

NPV is transmitted by fly feces on leaves as well as the feces of other caterpillars. UV light does sanitize leaves but the only way to insure that the food you feed the caterpillars is clean is to clean it with a mild bleach solution. Most of us hobbiests don't do this because it is a pain and NPV does not happen that often. It does happen though and the only way to be 100% sure it doesn't is the bleach solution.

Watch the others (as I assume you are being the good papa you are). Use good hygiene practices (washing hands, etc.) before handling any other caterpillars. This is not contagious to people.

Let us know what happens,
Elisabeth

Thanks, Elisabeth. Let me talk out loud here a bit.

First, there's no obvious odor, but I sometimes miss smells.

Because of the black color of the caterpillar, I considered NPV. But then I read the FAQ:

"Runny, wet, or moist frass (poop), regurgitating goo, shriveling filaments at either end, sluggishness, and discolouration of the skin."

Runny poop? Nope.
Regurgitating goo? Nope.
Shriveling filaments? Nope.
Sluggishness? Yes, but he's dying, so...
Discoloration of the skin? Yes.

I also found this very informative article that describes NPV-infested larva as having disintegrated, liquified skin. While the dead cat is deflated, his skin doesn't appear liquified.

Let me qualify that. There *is* a black stain on the bag where he died, so some liquification has taken place. But it seems to be more internal than external.

Additionally, I ran across this: "According to insect pathologist Dr. Harry Kaya of UC Davis, cytoplasmic polyhedrosis has never been detected in the wild. It is primarily a laboratory phenomenon. But, obviously, it does exist in the wild, but just at a benign level. It is the laboratory conditions that give the virus a prime opportunity to thrive."

I'm not a lab operation -- my eggs and cats are collected every year off of garden plants. Opportunity for NPV transmission seems really low under those conditions.

Anyways, primarily on the basis of "no runny poop", I moved NPV down the list. However, I do note that we went from "smudgy skin" to "dead and black" in 72 hours, which would be consistent with NPV.

OE is also on the diagnosis tree because of the smudgy appearance. Tdogmom's website associates the discoloration with OE. I'll be testing the other 8 butteflies, assuming they eclose, for OE. I haven't run across any descriptions of cats turning black with OE.

So Pseudomonas rose to the top somewhat by default: it causes "black death", but without the runny poop. More than that, I don't know (yet).

I'll be watching those chrysalises carefully.

Jeff

Jeff,
On that second guy, I'd be curious as to what happens. You said he is slow to pupate. I'm wondering more along the lines of Oe...but he does look like he's got that weird look at about the 1/4 of the way from the back end. The colouring is what makes me wonder whether this is Oe related.

You know, it could also be a combination. Keep us posted, please.

Sherry

Hi Jeff,

Sadly I have had the depressing experience of watching monarch cats die while in the process of pupating where they just seem to deflate and hang while their bodies stretch out lifeless. I have also had some that just dissolved almost overnight. I never did find out what actually killed them but it is disheartening to say the least.

I also had similar deaths with gulf frits and pipe vine swallowtail cats. In fact, during the past two days or so I have seen two of the latter die while attempting to pupate. I am hoping the other ones will not turn out to have been infected. I bleach-clean the cages in spring but I have chosen to take the chances after that because it is so time-consuming and tedious when you are working with large numbers of cats. Do the best you can but try not to get too discouraged because you are doing better than they would get out in your backyard.

I do have a question for the more experienced members of our group. Has anyone tried using the antibacterial or antifungal spray that has at times been advertised on some of the monarch websites. Alledgedly, it can be sprayed on the sick cat as well as the leaves. It was a bit expensive and my own cats had already gone on to that big butterfly garden in the skies so I just kind of forgot about it.

The sick cat pupated overnight.

I didn't have a good way to keep the three pupae in quarantine, so I jerry-rigged something together

{{gwi:509097}}

Sicko is on the bottom; the other two are on the top.

Jeff

Jeff;
The more I look at it the more I think it is OE. Last year we had a really bad outbreak in the house. NPV has a really bad smell according to the instructor of the IBBA disease course. I believe that NPV is more prevelant than just found in lab situations. There are papers describing it in the field. I also have a personal communication with the director of the karner blue project in Toledo who said they lost a large group of caterpillars quickly. They think it was infected food material.

Anyhow, my hubby posted these pictures of the OE outbreak we had last year. Take a look at them.

-Elisabeth

{{gwi:509094}}
http://mommyfiles.com/butterfly/miscelaneaou004.jpg
http://mommyfiles.com/butterfly/miscelaneaou005.jpg
http://mommyfiles.com/butterfly/miscelaneaou006.jpg
http://mommyfiles.com/butterfly/miscelaneaou007.jpg
http://mommyfiles.com/butterfly/miscelaneaou008.jpg
http://mommyfiles.com/butterfly/miscelaneaou009.jpg

By the way, you probably know that OE is a microsporidia in the same group with nosema. These diseases live with their hosts often only causing problems when they have "stressful" conditions. Typically overcrowding. So, we see microsporidia diseases later in the season as more caterpillars are raised from the same food sources. We think we had an outbreak of a microsporidia in our zebra population in the house last year. Anyway, as you know, OE can kill at any stage or not kill at all. But it weakens it's host and set's it up for infection with another disease. So, while it may have a bacterial infection, that may be only half the story.
-Elisabeth

Elisabeth,

That's a really good point about the secondary infections.

Something that I forgot to mention: the dead cat in the first picture was on the side of the bag, curled up on the day before I posted. I assumed he was pupating: classic J shape, seemed to have silk on the prolegs.

Then, when I opened the bag an hour later, he was *back on milkweed.* I just chalked it up to a mistaken memory on my part. And he actually looked mostly OK at that time. And then the next day he was dead. In fact, at first I assumed that he was the other guy -- except that the smudge-marks were a unique identifier.

So it makes a lot of sense to me that he had a secondary infection on top of the OE.

--

Your first OE pic was interesting in that its appearance is more liquid and brown rather than smudgy and black. It almost looks like tobacco juice. And the cat looks healthy except for that single lesion.

So I need to broaden my range of what to look for with OE.

---

Sicko's chrysalis shows a brown mark across the top. It's slight, but I'm about ready to pull the plug. His quarantine-mates look fine so far. I'm trying to get my hands on a 100x scope before they eclose.

Jeff

I don't know if you have looked for it before...

You can use 40X just fine. It will just be a lot smaller. I actually like to start with this magnification. The spores are much smaller than the scales and tend to cluster together, so it can be easy to miss if you are trying to scan with a higher magnification. I guess I am trying to say that higher is not necessary but fun to look at.

Good luck, let us know how it turns out,
Elisabeth

Hello,

My monarch cat has been acting off and I'm quite sure that he is sick. He molts but he doesn't get any larger, just longer and he has kind of an odd discoloration to him. I am afraid he is going to die from black death. But the thing is he is still eating and is currently eating now. Does anyone know what is wrong? Also, I do not raise them in a cage, I leave them outside on my milkweed.