help please for sick caterpillars

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    I have seven caterpillars that have been inside on a swan plant since eggs – 6 were eating our milkweed for 2 weeks and a 7th a few days younger. We got 2 new plants and in the afternoon the 6 larger ones moved onto a new plant and were all eating away. The next morning the 6 were oozing green stuff, not moving and some had fallen onto the soil. They seemed to be dying. The shop assures me the new plants were not sprayed but I took them away anyway, brought plants from another shop and they stopped oozing and are generally quite active again although not eating and don’t want to stay on the plants.

    I’m not sure whether they are too unwell to eat, big enough to stop eating and think about making cocoons, if I should leave them or be doing something. Any help would be much appreciated.

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    We seem to have an abundance of caterpillars and they are thriving in the butterfly house and pupating very well.

    There seems to be a lot out on our plants in the gardens as well that are coming through, so we shall still monitor and see how things progress.


    Gillian Eadie

    Hello Jacqui

    Well, as you know, all of the caterpillars died from Feb 25th (when they started to get sick) until the conference mid-March.  I learned a lot about the ‘do’s’ and ‘don’t’s’ from the conference speakers and attendees, though, so the new ones are looking MUCH healthier. I have a full house again from very tiny larvae to big healthy ones that are just starting to get ready to pupate (five ‘went up’ today). The things I have done differently began with cleaning out the whole raising area with the 2% bleach solution recommended and making sure that the plants were washed before putting them in the ‘butterfly house’.

    Other actions I have taken are: 1. not handling them and doing any necessary transfers using a leaf  2. keeping the butterfly house relatively dry, apart from direct, light watering into the pots for the plants 3. trying to make sure that there are not more than three or four caterpillars on any one big plant (at least I tried – they do have a habit of making their own arrangements!) 4. giving them as much sun as possible, although I do hang a second light net over the walls (also net) when the caterpillars are climbing up the sides, to protect them from wasps) 5. only using home-grown plants.

    So far, so good and I haven’t lost any yet. I’ll keep you posted. I saw another butterfly around today so I am wondering if there will be any ‘non-caterpillar’ time during the winter?!! I also planted a new round of seeds so there will be a plentiful supply of plants for later on.

    Thank you for all your help, Jacqui and for all of the support people you have here – it is such a thrill to see the new life-cycle going well.




    Hi Jacqui! Unfortunately all of my caterpillars in that batch (sort of all the same age) died.

    Since then though, there have been a new batch that have hatched and they seem to be doing ok. I think they are at about 3rd or 4th instar, and one of them is totally 5th instar and very fat and about to J up any day, which is awesome. I am keeping a close watch on him and hoping he makes it, he’s very fat and healthy looking!!

    I guess this kind of thing happens. I’ll plant these plants in the garden (they’re currently in pots) and hopefully they’ll do ok and shed some seeds for next year. 🙂



    I wonder how it’s going for you now, Gillian, Tinzaroo, Lisa and RaisingStripes?

    Would be good to have an update on progress as things have changed. Have you solved the problem? Or have you changed anything radically and noticed a big difference?

    Hope things have come right for you.




    Hi again Jacqui

    This is the first year I’ve ever had swan plants, cats and butterflies.

    From the first batch of cats I had, which was about 6, I had 5 chrysalises successfully eclose into beautiful, perfect butterflies. The one that didn’t, fell off whilst pupating and I couldn’t save him.

    This last batch of cats, I started out with about 24 cats, and I’ve had 6 chrysalises. Five have eclosed so far, all successful apart from one with a tiny tear on her wing but she seemed to fly away ok. I have one chrysalis yet to hatch, but it looks very small and a little bit irregular in shape. So of the approximately 18 cats I had / have, all are now dead or dying!!! I came home today, and it seems that they are all in that lethargic state, drooping off the leaves, or have already dropped onto the deck.

    The plants are all watered daily, there are no aphids or other nasties on the plants that I can see, and none of the cats look like they have been bitten or sucked dry by wasps. I am just at my wits end.

    I have another batch of 4 plants with many tiny cats on … these are separate from the 7 plants with the sick / dying cats on. I don’t think I have overcrowded my plants? I’m hoping the 4 separate plants with the tiny cats on might be ok.

    Looking forward to any suggestions or help, and hope you are able to find out some info Jacqui from the pathology of the dead cats you had.

    Cheers everyone, Tina



    I have only really reared cats this year (other than as a kid) and have also had cats hang in the J and then start to pupate,  moult only the head, then die. Also some hanging in the J and then just shrivelling up. However I put all this down to feeding them zucchini as I ran out of swanplant, and it seemed to me they were pupating too early due to the food source. Interesting to hear others have had the same experience with plant fed cats.

    I did get hold of some plants, and transferred the remaining cats onto them, they seem to be growing at an exponential rate. Doing very well.

    I had about 40 feeding on zucchini, and lost about 10 to either oozing, non pupation (shrivelling up), or partial pupation.

    Have about 30 chrysalises (some look malformed) and fingers crossed they eclose ok.



    Hi Jacqui This is my second year in a row with the monarchs but growing up I don’t recall anything much going wrong with them other than wasps. plus we had a healthy crop of cats and a good sucessful season at the kids kindy in Pakuranga.

    Last year nearly all caterpillars survived other than the odd wasp etc. Don’t ever recall loosing a caterpillar forming a chrysalis before this year.

     Early this season all the cats were fine untill the problem with Chrysalis formation. I lost about 4 with that.

     Lately that hasn’t been the issue but rather slow dying cats the seemed to be thriving in the first week doubling in size almost daily. 4 out of 4 died over a couple of days in the last position. ( which I had moved there to get away from wasps and hopping spiders) On the other side of the house and orginal position at one point I had 30 odd cats and I ended up with only a couple of Chrysalis’s. A couple definately were eaten by wasps but mostly this slow dying thing. Just as one lady described earlier they seem to perk up  if you blow on them or disturb them but soon let go again until only a couple of feet are hanging on and die.

    Sorry can’t be more specific re loss numbers but a huge amount.perhaps 90% . Please note this has just been in the last month or so not early in season. I wondered if due to the drought??? after some thought  think I counted 35 or 36 cats and perhaps 3 chrysalis’s formed from those soa  huge loss. no more cats left now.




    Hello Lisa and tinzaroo

    We are having some dead caterpillars examined by a pathologist and may have some information on Monday. I will post the results here and hopefully we can then do something about addressing it.

    How many years have you been raising Monarchs?

    Could you please estimate the percentage of unsuccessful (i.e. dead) ones to ones that get to become butterflies?




    Hi all

    I’m having trouble with my cats, too. This is my first season with swan plants and rearing cats and butterflies. I’ve had about 11 successful chrysalises so far, and it’s been a lot of fun! I’ve bought my swan plants from Plant Barn in Takapuna, and haven’t had any problems til now. Last week I had about 30 healthy cats, now I have about 7. They all seem to be dying off! I don’t think they’ve been sucked dry by anything or bitten, they look perfect. They just stop eating, become lethargic and fall off the plant and lie there and die over the course of a day or so.

    They haven’t been doing the green goo thing, although one or two did do that last week. These ones this week, are just dying for no reason, or so it seems. After the big rains we had in Auckland, they seem to be doing really badly! Could it have been the wet weather??

    I have some new little cats on another separate batch of plants, and now I see one of these looks kind of folded over and lethargic, although he does move and perk up when I gently touch him.

    Just trying to work out what I have done wrong, or if it’s the time of year! Thanks for any advice x



     Are these oozing cats being reared inside?. Are you sure its not from being biten by something as they ooz when injured. I have also had problems but trust the centre that they hadn’t been sprayed as leaves had cats on them and looked a bit chewed plus my cats wouldn’t eat them( perhaps too much milk in the older plants) for my spoilt cat breed on baby swan plant leaves. Who knows but I’m worried there may be something more sinister going on with our cats this year. Too many posiblities. Interesting feed.



    This is an interesting feed. I also have had a terrible problem with caterpillars and too many things that may have caused the problems.

    Firstly I had alot of cats try to form the Chrysalis and die right in the middle of the process. They would form the j then the Chrysalis would form on the head next thing the cat was limp and dead. There were so may things that could have been I though – over heating, over crowding( i find cats very territorial and appear to bite each other when they bump into each other) possibly causing problems with the molt of that final skin..OE…

    Next issue I have lost about 2/3rds of my cats to something. They start growing well then get about half sized and stop eating, stop growing, they appear to dehydrate and start hanging upside down slowly dying over a few days. Some are still hanging dead days later. I’m also concerned re whats caused this.

    I also got swan plants from the garden centre who imformed me they aren’t allow to spray because they are used as a food source. They swish or transferr the cats onto their large plants. (My cats wouldn’t eat the new swan plants anyway as only like the tender plants I have of thousands of self seeded babies.) I’m confident that it’s not the plants. Also I found  if I watered the plants leaves they can end up with a dusty looking residue on them. I tried to wipe that off when I first got them with no sucess even after a couple of times so another reason I trust the garden centre. (  Plus the fact I spotted baby cats on them in the centre)

    So ruling out the plants possibly now according to posts could be bacteria? I need to keep the plants watered as they do dry out and go limp being in pots. I have heaps of aphids on the plant so possibly this could be a problem? I thought possibly the heat as I tranfered what looked to be healthy small cats which continued to grow quickly then within the space of a few days they lot were dead. Although cats died the cooler side also.

    I had a few get right the way through being inside without me even knowing they were there for the first week. The containers were left in a bucket of water neglected on the bench which I hadn’t got around to potting yet. Hey perhaps they don’t like all the care. haha. Unfortunately I don’t know if they all survived inside as I don’t know how many there were to start with but they managed to get through that mid sized stage.

    Will continue to read this feed to see any other ideas. Now no more cats or eggs just butterflies to emerge.



    We’ve had such a poor season this year compared to other years.

    We were only placing small amounts of caterpillars into the butterfly house at a time ( 20 – 30) and these caterpillars would just slow right down and die.

    There was no smell in the room or oozing liquid from the caterpillars at all. They would just stop eating and just die.

    The butterfly room temps got to a max of 34 deg inside on some days and there is sufficient airflow through the area.

    We then moved the caterpillars into a castle on the deck and they slowed down out there as well. So we decided to try outside on the big plants and they were going well until the wasps found a way in and they demolished a lot of them ;(

    Certainly hope we get some answers as this has been the worst season for loosing caterpillars. We’ve had a lot more preying mantis and wasps in the gardens this year, and oh the aphids they were breeding prolifically on the plants no matter what we did.


    We will be lucky to tag 25 butterflies this year, as previous years we’ve been up over the 1200 mark.


    Gillian Eadie

    Hello Raasingstripes

    Sorry to hear about those caterpillars – it is distressing to see them go, isn’t it? After the Conference last weekend, it seems that there are a lot of things that might have contributed to the deaths and you can see Jacqui’s appeal for information in an earlier post. however, because all of mine died progressively over 3 weeks or so, and it all started after I put new plants in the ‘house’, I can’t overlook spray being on the plants. My supplier denied the possibility but there were other people at the conference who had lost caterpillars  who also purchased their plants from the same garden chain.

    But overcrowding (too many caterpillars on a plant), handling the caterpillars too much, and ants/wasps/tachinid flies were all possible causes!

    It will be interesting to see what Jacqui’s research people uncover.

    Good luck with your last one!



    Gillian, I am having the same plan issues as you. I just called up the nursery I bought them from today and I said my cats have been poison, I need to know what poison was used. They denied it but called their supplier and sure enough the plants have been sprayed with some sort of viral spray.
    My cats are also oozing and writhing although there is 1 big one still chomping away and looks ok. Maybe your got the same poison too. And some react differently to the poison.



    At the conference Myron Zalucki said he didn’t know what it could be but he suspected it could be overcrowding. But then his area of interest is not butterfly diseases as such.

    There were two other people from different parts of Auckland attending the conference (St Heliers and North Shore) that also said they were experiencing problems similar to this. Myron suggested that it could be overcrowding.

    I have taken some samples of dead caterpillars into a pathologist for testing. When I have some feedback I will post it here. What would be helpful would be to get an estimate as to how many people are losing and also how many years’ experience they have had raising Monarchs etc.

    People who have raised Monarchs for several years have experienced some highs and some lows. They realise it’s not a race – it’s not about releasing “more” than someone else. Some people start to raise Monarchs/butterflies and are so thoroughly disappointed when one dies; they expect that they will have 100% success. An impossibility, of course.

    The more you have of one species, the more likely a successful attack by predators, parasites, pathogens etc will be – as they have found the perfect breeding ground.

    So if people who have never experienced this “problem” before could post here in the forum an estimate of:

    – How many years they’ve been breeding Monarchs.

    – How many they successfully raised this year

    – How many have been not successful this year

    it would be helpful.


    Gillian Eadie

    Thank you, Jacqui

    I think the division between the healthy and sick ones can be explained if NDV is really the cause – I didn’t start hosing out the floor of the caterpillar house until halfway through the season. By that time, there were 100+ chrysalis up top and they have all emerged unscathed.

    I’ll keep up my research though to be sure so that I can avoid losing any more.



    Hello Gillian – you could have found the answer. If things improve, you will know that you have… It does seem strange that some of yours are fine while others are not.

    Keep us posted – or an update please at the conference. 🙂 I don’t know that any of our speakers know much about NPV.

    I don’t have time to look right now, but would recommend this site here:

    Catch you soon.



    Gillian Eadie

    Hello again everyone

    I am wondering if I have found the cause of the deaths of 50+ caterpillars over the past few weeks. I was casting around the internet and found this article. Now I am worried that I have caused the problem myself because when we started the new ’round’ of caterpillars, to keep the plastic covering on the ground clean, I took to hosing out the area each night and there would often be a puddle or two of water trapped in the corners that may not completely evaporate until the next morning.

    This article suggests I have created a perfect breeding ground for Nuclear Polyhedrosis Virus (NPV).  100+ of the earlier caterpillars have now all emerged into strong healthy butterflies but it is the later 50+ that have died in much the way described here. I am upset to think that I may have let it spread!!

    I’d be interested in comments as I don’t know how scientifically correct the article is – or where the writer is based. I want to avoid making mistakes in the future …..
    Causes and Prevention of Monarch “Black Death”
    Caterpillar: Pseudomonas Bacteria
    Chrysalis: Nuclear Polyhedrosis Virus

    The interesting thing is this: The main way to help prevent either disease is to keep the rearing containers DRY. Warm, moist environments promote the growth and spread of the bacterial and viral ‘predators’ and cause unclean conditions. People can spread these diseases to caterpillars through contact with their hands. The bacteria are usually not spread person-to-person,
    ALTHOUGH Pseudomonas bacteria CAN be a problem particularly if it infects the human eye; it can ulcerate the cornea and lead to blindness. (NOTE: There are LOADS of different types of Pseudomonas bacteria�it is one of the bacteria that causes “swimmer’s ear” aka otitis and is commonly the bacteria found in hot tubs.)
    One way to notice if a caterpillar (aka “cat”) has been infected by the Nuclear Polyhedrosis Virus (NPV) is if the caterpillar has the following symptoms: Runny, wet, or moist frass (poop), regurgitating goo, shriveling filaments at either end, sluggishness, and discolouration of the skin.
    These “cats” should be removed from the other cats and destroyed since the virus is deadly. Period. It is spread from one caterpillar to another through the excretions (the runny frass or regurgitations) the infected cat has left on leaves that are then eaten by another cat.
    How to destroy the NPV? Wash and dry the leaves the cats are fed. Ultra-violet light has also been found to destroy the virus so it can be used to “disinfect” habitats and rearing containers. A bleach solution also works.
    Pseudomonas bacteria is found in warm, moist areas and is common in the soil and on plants. This is why it is CRITICAL to keep all rearing containers dry. Since it is found on plants, it is practically impossible to really eliminate this particular bacteria.
    One thing I do is wipe the leaves I feed to my Monarch cats with those anti-bacterial Kleenex-brand tissues.



    Wow that would have been a thrill relesasing 15! My best so far is 6 at once 🙂 Yes, I have lots of little plants growing on now, as I’m determined to be far better set up next year, and I have 3 varieties of swan plant seed in, fingers crossed some of them grow!


    Gillian Eadie

    Thank you BlueSkyBee – it seems that you came into monarch-raising in the same way as I did! Probably rescuing every caterpillar I came across was a way too ambitious idea and has created the challenge this year. I think my supply of plants will be plentiful for next year, though. We released 15 butterflies today which was a great thrill … I just hope the not-very-well ones will hang in there to get to that stage.



    I hope your troubles will soon be over Gillian, and you’ll have healthy cats from now on.

    I must say, reading these threads makes me wary of buying swan  pants, which I have been forced to do this year, as I started off with ONE self seeded plant, thus falling unexpectedly into monarch raising in a big way! However, I do sigh with relief if I spy tiny cats on plants I buy, as it means it would be less likely for them to be sprayed, and adding new genetics to the area can only be a good thing I guess, only downside is it’s more cats to find food for! 🙂


    Gillian Eadie

    Thank you again, Norm

    I’m sad to think that last one died before pupating, but I think it may have been too sick to emerge, anyway.

    To be honest, I am again really suspicious of the plants, although the garden centre says they were not sprayed. Apart from the ones affected as per my photographs, I can’t see anything else untoward and, from now on, I will be doing my best to rely on plants I have grown myself.

    The only real change in the health of the catepillars happened when I introduced the new plants and I can’t see any bites or otherwise on the rest – they are just lethargic, lacking in body tone and basically sick-looking. And a few fall by the wayside each day. The ones I have isolated on new, home-grown plants, seem happy enough so far, but time will tell.

    The first 100 or so (before introducing the garden centre plants) are fine and are rapidly turning into healthy butterflies.

    I’m keen to have a more trained eye so that I can identify what is happening ….

    Thank you for your help.




    The latest photo looks like the caterpillar may have attached itself to the leaf in preparation to pupate but then died, would this be the case?

    Ants don’t normally attack a large live caterpillar, but will hone in on it for food when it is dead.

    The brown splodges on the leaves, if they are beneath or where the caterpillar was, can indicate contents dripping from the ruptured skin from a diseased and dying/dead caterpillar.

    I suspect that you may possibly have  two seperate problems with your caterpillars.



    Latest photos from Gillian are here:



    Gillian Eadie

    Thank you for your very helpful replies, Norm and Jacqui. I can recall seeing both beetles that look like the images of soldier beetles on the internet and a few bronze-backed flies around the butterfly house in the past but I have just shooed them away, not realizing that they are predators. I have looked really closely but I can’t see any ‘foreign’ pupae or grubs so I am hoping that they don’t all have parasites.

    I haven’t found any more caterpillars that appear to have the bite on the back but I am still losing 3 – 6 a day through deflation or dehydration. (I have taken to misting the plants in case it is the latter). I am keeping a close eye on some that have been isolated from the rest, though, as Jacqui suggests. I can’t see any spiders on the leaves but there are a lot of little black blobs on the plants, some suspended from leaves. I’m not sure if these are just caterpillar droppings – they are not the same as the earlier ones, but then, the caterpillars are much more sluggish and not eating much. There are splodges of browny liquid in places, too. I have tried to photograph the black dots for you to see so I will post them soon.

    Fortunately, healthy strong butterflies are emerging from the earlier batch so I am confident I will have 100+ released into the environment.Kindest regards


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