Sick or diseased larvae??? Help???

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  • #42828


    So I grow a Swanhaven – that is, I grow one enormous bush or a collection of swan plants – in anticipation of the high productivity of monarchs. Due to wasps, I gathered a generation of caterpillars to raise them myself, and gather fresh cuttings from the mother plants each day. I also give them pumpkin, which saved a generation of caterpillars the previous year when they ate the smaller mother plants dry.

    I’ve raised Monarchs before, all to healthy adults, but this generation was alarmingly different. The caterpillars all grew to healthy hanging size, then…things went to custard. The first one struggled to even hang into his J-shape and died after days of twitching, unchanged. The rest hung themselves, only to die after they split their skin to release their green chrysalis from their heads. Split-necked, still primarily caterpillar-form, they also died. I know from the rare opportunity of a personal viewing that the caterpillar’s removal of skin to expose its green form, eventually to take the chrysalis shape, takes twenty seconds at most, and the process is fluid, like slowly squeezing toothpaste from the neck of the tube.

    Only a few made it to healthy chrysalises…and then the trouble didn’t stop there. So far three butterflies have hatched and I still expect three or so more to, but two butterflies have emerged with wings that do not straighten properly. They are born crippled and cannot fly, and so cannot survive. Only one has so far reportedly hatched and flown away.

    Please, can anyone explain the reason for these deformities??? I’ve never experienced a brood of Monarchs like this, indoors or out.

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  • #42829


    Hi Shoutfinder

    Sadly, this can happen. We humans tend to think in terms of the predators and parasites we can SEE, and forget that there are things in our environment that we can’t see that could cause a problem.

    It could well be a pathogen or a virus – and if one caterpillar had it, or one female monarch had it, it could spread among the others.

    We cover this in some detail in our course. You can also learn a lot from clicking on the hot tag to the right “disease”. And this is a helpful website:

    So, what can you do? You set out to raise healthy monarchs and thought you were doing the right thing. If you think about it in human terms… where would a toddler be more likely to get sick: when they’re with other toddlers, or in your own home? Of course, it’s more likely when they’re mixing with other children. Swanhavens are the perfect place for pathogens, predators and parasites to get hold of monarchs, and with lots of monarch caterpillars, the pathogens can spread so quickly.

    I learned the hard way too. I’ve been rescuing other people’s caterpillars this year, and just hope I’m not biting off more than I can chew, not asking for trouble.

    If you can, for next year, separate your swan plants by groups of other shrubs that will give shelter and dimension to your butterfly garden. I hope you will pursue the interest, the monarchs need dedicated enthusiasts like you.

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