How to care for Monarch caterpillars until they reach maturity

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  • #47871


    Hi there,

    Our family have been watching for a couple of weeks several Monarch caterpillars growing on one of two of their special plants (not sure what the plants are called) in our garden. In the past week the caterpillars have got a lot bigger and to our horror birds (Kingfishers) have taken all but two. Today we put a large clear plastic bag over the plant and the remaining two seem to be safe. Couple of questions: (1) Is the plastic bag ok to use or will it get too hot for the caterpillars to survive (they seen fine at the end of today) or is there something better to use as protection? (2) They are chomping through the leaves and there aren’t many left on their plant – will they run out of food or begin eating other parts of the plant (which is quite large 1.5 metres high) or should we somehow introduce leaves from the other plant (that has no caterpillars on)? (3) How long will it be before they turn into a Chrysalis?

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    We have had an amazing time nurturing cats through to Chrysalises, and because of a shortage of milkweed plants we have progressively migrated several cats to two indoors habitats (set up and maintained strictly as suggested online for Monarchs) and gone to other plants in the neighbourhood for leaves to feed the brood. We have two Chrysalises on an outside plant (we moved them the day they started to “wander” and in a couple of days they began to pupate). Three more we transported inside and they pupated on the netting roof of the enclosure. We are now down to three cats – two are growing quickly, but we have two small ones (about 2.5cm) that just don’t seem to want to eat or move for the past couple of days. They are alive but just don’t seem interested in eating or moving in their new habitat. We thought it may have been because there was a large cat in their enclosure so we moved him out to the other, but no change to the little fellows. Any suggestions?

    The other questions is, how long before the Chrysalises turn into Butterflies? The first two that we migrated a couple of weeks ago are still Chrysalises – and are still a bright green colour.

    Any help and suggestions at this stage would be appreciated!!!




    What a nice vision you write of your place.
    You have much better plant growing climate than here in the rocky/rolly city.
    The biggest problem you have is not enough Asclepias spp. (Swan plants)!!
    That is a big grin.

    I have just learned about some of the varieties of Buddleia and I purchased a couple when the MBNZT came to Christchurch. I now have one of those Yellow globe (Buddleja globosa) varieties. Typically we have the “”summer lilac” version – (Buddleja davidii) -or the long lilac coloured flower. Anyway, these bushes / shrubs appear to be the top of the list of the butterfly & insect feeder flowers. ‘Why’ is a good question.

    Keep the wasps off the caterpillars.. They won’t worry the Monarch butterflies though. If you have a lot of wasps – Is been their season – perhaps an observation of activity might locate a nest. I had a nest in my roof in January. The exterminator dealt to that.
    Meanwhile, enjoy the observing the devouring ability of the cats as they grow.

    My son had a caterpillar come inside his house and make a chrysalis under a kitchen chair!! That was spooky when it emerged indoors from under the chair!
    A newly emerged butterfly, when extends and dried after a an hour or few, can be handled quite comfortably, tho gently. Let it walk all over your hand, arm or whatever. It will fly off when it is dry enough and (light & strong enough).
    Jacqui has given you good description of there new emergence.

    Regards, Barry P.



    Hi Again Barry,

    Our location is Rothesay Bay, North Shore, Auckland City, 500 meters from the sea. Our garden, or more correctly, the area where the cats, Chrysalises and Butterflies reside, is a narrow pathway (wooden walkway) tall hedge one side, retaining wall the other with a variety of wild plants along the side – two of which are Swan Plants, and a Pohutakawa midway along the walkway. At the top of the driveway (60 meters) are some small fury trunk palms, birds of paradise randomly dotted around, and a broad green leaved, large girthed plant with spindly branches and white globe, round flower heads This plant is a potential problem as it attracts dozens of small insects, flies AND wasps. Googled it and could be a sort of Buddleja, not sure). I was however startled today to find a beautiful Monarch perched on this plant with wasps zooming all over.

    We now have the fat cat inside (eating like crazy, never seen a creature poo so much) but there are two only remaining outside one about 2.5cm the other a micro specimen only a couple of mm in size. Should/could we house these two in the same container as the larger cat (which must be getting close to wanting to wander and hang)?




    2nd part – – – The caterpillars will go to wherever their energy takes them. I am intrigued by what criteria – Temperature, humidity, Daylight, Hormones, pH, Gene maturity, energy (sugar / fat content) or whatever – causes the cat to stop travelling and pupate. Some will form on the host plant, some might travel 15 or more metres away and climb 2.5 metres up a tree, vine, a nearby plant, such as buddleia, tomato or silverbeet. Ultimately, they are not fussy. They might mill around for a few days before they settle to hang in a [ J ].
    In a caterpillar castle, they will congregate on the top / roof of the enclosure.
    But that’s my observation and conclusion. {BEP}.



    Hi Shell & Kids.
    It would be nice to know where in NZ your garden is. There is a large variation of advice depending on location.
    Your question:- Predators > Monarchs do not have large animal predators. The colouring (yellow/ black stripes) of the caterpillars and the Butterflies themselves are a deterrent to nearly all birds.
    The feeding on the Swan plant makes the cats very toxic. Actually the sap of the swan plant (latex) is bad for humans and farm livestock. There is a lot of good reading to be Googled on the subjects. So, birds won’t touch the cats, well not after they have thrown up on the first one!! Hihi. Have you tried to eat a quince? Yuk!
    Other pests are Wasps of various types and microbial parasites. Both these will enjoy nourishing meals made of Caterpillar and Chrysalis.

    Jacqui has made some good comments on your question. {BEP}



    Hi Barry,

    Thank you so much for the advice and pointers. Very helpful! Checked the two Chrysalis and they are a bright green and have the gold spots.

    What predators in particular go after the Monarchs when they are released (Kingfishers?) and do the butterflies tend to hang around the area/location that they grew up in?




    Hi, from bright, warm, sunny Christchurch.
    The Caterpillars will grow about as large as your little finger. They will wander off when ready to pupate. They might stay on the plant, They will climb to the top of a caterpillar castle, they may travel as many as 15 meters away and climb 3-metres high. The sills & soffits of houses are liked!
    A lot of what you ask is for you to observe and make the judgement call. I can take cats form outdoors into a castle when they have but 2 or 3days feeding /maturing left. This way I do not have to support a lot of Asclepias in the castle.
    ‘Fresh’ chrysalis are attractive to wasps.
    As long as the cats have fresh food, not necessarily growing live, they will mature and pupate.
    Depending on temperature, (your location in NZ) the cat may be in its [ J ] state for 5 days before it begins to chrisalyse. That will take less than an hour (typically).
    Cats will do their own thing when they are mature enough. If you place a wandering cat on a swan plant, if it feeds, it will; else it will have enough energy to go somewhere ‘nice’.
    Cats may be handled freely, though gently. I try to avoid ‘bruising’ although I have dropped cats from a height onto concrete and they have cycled into healthy butterflies. So they are quite hardy.
    Healthy Pupa should be bright green, with their gold spots. A Chrysalis that is dull or milky is probably diseased. {BEP}



    Hi All,

    Since we last communicated on 22 April, we have had a lot of success. First moving two caterpillars (about 5 days apart when we noticed that each was getting close to 5cm and began wandering away from the their netted Swan Plant) to a new plant. The second plant we don’t believe is a milkweed variety, but it has branches and plenty of large, sturdy green leaves for shelter. In both cases the caterpillars hung around on this plant for a day or so and both then started their pupate cycle. They are doing well (dark green at the moment).

    We have another two caterpillars of differing ages/sizes that “just appeared” on the netted Swan Plant. One of them (the larger) looked as though it was in trouble – still and clinging to the netting (rather than the plant). So this one has been inside with us in a large glass and netting covered container. It is chomping through hand-picked Swan Plant leaves and is almost 4cm (gee they grow quickly!).

    Should we transfer this one to the plant with the two chrysalis? Or has it become too used to indoors? If a transfer is a “yes” so it can start it’s pupate cycle, then how can we tell (apart from it looking about 5cm) when the time is right to make the transfer?

    Any advice and other tips would be great!



    Thanks so much for that. Know what to do now.

    Now the challenge is to nurture the caterpillars to Chrysalis and then out to Fly!! A mission, but wonderfully with it.


    Will keep you posted with progress!



    No they’re most unlikely to get hurt when they emerge. The butterflies can take several hours before they want to fly. Don’t be in a rush to move them. They need to be completely dry, you’ll note that the wing tips are “soft” and floppy, like the bottom of a silk skirt, until they dry. Only when the wings are dry does the butterfly “try out” its wings, by opening and closing them. Give it half an hour or another hour maybe, and it will want to fly.

    Once they get to the stage where they are opening and shutting their wings, gently put a finger down in front of the butterfly’s face and down to touch the front legs. It will climb onto your finger. Or should. Then you can carry it out of the netted area and carefully transfer it in the same way onto a flower or leaf in a sheltered area – maximum sun, minimum wind.



    Thanks All,

    Both plants are the same.

    The little guys must be getting close to 5cm. So we will keep an eye on them until they pupate.

    Question: If we have them in the net (for protection) are they likely to get injured when they emerge from their Chrysalis? When we see that they are ready to fly should we set them free ASAP?



    You are so right, Errol! 🙂 Thanks for that.



    Jacqui, I thinks it’s around 5 cm (about 2 inches) that they will start to turn into their chrysalis.



    Hi there

    Just a thought… the other plant with spent chrysalises on it may not necessarily be a swan plant. Quite often the caterpillars search for a “desirable location” on which to pupate. If you pull a leaf off this plant, and a milky latex oozes ot of the stem where you’ve torn the leaf off, then yes it is bond to be a swan plant.

    They usually pupate when they are about 2.5cm long. Hope that helps!




    Hi Jacqui,

    Thank you so much for your quick response as we are really concerned about what we can do.

    Ok, we will get some netting tomorrow.

    We are at Rothesay Bay, North Shore, Auckland.

    We are not absolutely sure that it was the Kingfishers, however these little guys don’t normally turn up in our area, but one, two, three hovered over the “Swan Tree” (thanks for that we Googled the plant and Bingo) for days, so we “assumed”…

    Yes, transferring to the other plant is an option, just wanted to know that they will be happy there (we noticed that the second plant has had some spent chrysalis pods on the branches, so should be good, yes?

    Unfortunately we don’t know exactly how many weeks old they are, but if they are getting quite big could it be soon that they will begin to morph into a Chrysalis?

    Thank you.



    Hi Shelland Kids

    1. It will probably get too hot but it’s hard to know as you do’t tell s what climatic zone you’re in. You would probably be better getting an old net curtain.

    I’m surprised that kingfishers are eating them. We’ve never heard of kingfishers eating them – the only known bird to find them tasty in NZ is the shining cuckoo and I think they will have migrated at this time of the year.

    2. They will eat the stems (soft ones) when they’ve run out of leaves. Will also eat the flowers and seed pods. But you could transfer them to the “other” plant so long as it’s milkweed, e.g. swan plant.

    3. They are in the larval (caterpillar) stage for about two weeks.

    Hope that’s helpful.

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