Flying Ant type bug killing my Monarchs

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  • #14502

    AliaMurray-Smith
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    Hi,

    I have a small insect that seems to be killing my Monarchs as they hang & try to change into a chrysalis. It is small & black, kind of looks like an ant with small clear wings.

    Once the caterpillar hangs & starts to wriggle around to peel off it’s skin one or two of these insects appear & crawl all over it. From what I can make out they wait for the chrysalis to form & then seem to lay eggs into it?? I think the Chrysalis then gets eaten from the inside when their eggs hatch? Not 100% sure, but after the chrysalis has been formed there seems to be tiny black dots (which I think is the eggs that have been ‘injected’). The Chrysalis then slowely turns black & dies. I had the same problem last year & even saw an old Chrysalis hollow & dead with a hole in it presumably where they exited?

    Can anyone shed some light on what these insects are & what I can do to save my Chrysalis? We are in Christchurch. Very sad to talk all about the proccess & watch the caterpillars etc every day for my preschooler when no butterflies actually eventuate!

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  • #25542

    Darren
    Participant

    discussion of cardenolides moved to its own thread:

    Cardenolide levels in milkweeds?

    #25537

    Darren
    Participant

    okay, to convert ug/.1g to percent divide by 1000. so 864ug/.1g is 0.86% cardenolides for A.curassavica according to Malcolm & Brower(1986). Rather different from the 0.2% figure from Agrawal & Fishbein (2008).

    Likewise for A.incarnata. Malcolm’s figure of 0.02% is nothing like Agrawal’s figure of 0.13%

    It would be interesting to do a literature search and see what other figures turn up. Like you Terry I have often read of the difference in cardenolide levels between A.curassavica and A.incarnata. Although the smell you report might also be due to other factors.

    #25535

    Terry
    Participant

    Got a feeling first paper was well out! I heard years ago that Curassavica was very toxic and I must admit when I liquidised some to soak some alternative food for my larvae in, the smell nearly knocked me unconscious. The others syriaca and Incarnata were quite mild. Although I admit there was nothing scientific in what I did! I think the info I read was on an experiment feeding monarch larvae to a certain bird that would eat those fed on low toxicity milkweeds and those fed on Curassavica, the curassavica ones were always rejected.

    #25534

    Darren
    Participant

    hmm, I just read another paper that says A.curassavica has 864ug/.1g dry leaf and A.incarnata has 24ug/.1g dry leaf.
    (http://peabody.research.yale.edu//jls/pdfs/1980s/1986/1986-40%284%29255-Malcolm.pdf)

    the previous paper claims .2% A.curassavica and A.incarnata .13%

    Its too late in the day for my brain to make the conversions but something doesn’t look right

    #25533

    Terry
    Participant

    Interesting! I knew that a Syriaca could be eaten if you boil the young shoots but as to the others I didn’t know they were that close in toxicity. Maybe Pteromalus puparum has evolved since being introduced to NZ to find new hosts. It definitely did not show interest in my Monarch pupae when I had them.

    #25532

    Darren
    Participant

    Apparently there is very little difference. The leaf cardenolides (dry mass), for A. curassavica is 0.2% and G. fruticosus is 0.19%

    source:
    http://www.pnas.org/content/suppl/2008/07/28/0802368105.DCSupplemental/0802368105SI.pdf#nameddest=ST1

    #25520

    Terry
    Participant

    I never had Pteromalus puparum attack Monarch pupae when I used to breed them in the UK and yet this Parasite attacks many other species and infiltrates my butterfly house every year at some time or another. I wonder if it was because my Monarch larvae were all fed on A Curasavica which has a very high poison content. It’s just a theory! but I would be interested to know how toxic the swan plants are that you use over in NZ.

    #25518

    Jacqui
    Moderator

    Hi Alia

    There are various ways – but how about breaking off the most luscious piece of milkweed (swan plant) you can, breaking up the end (so that it can absorb water) and putting the end in a jar of water (like a prize bloom at a show. Stand this jar in another dish of water – which will act like a moat. When you think your caterpillars are in their last instar (or as big as they’re going to get), make sure your hands are clean (i.e. no chemicals on them) and collect the caterpillars and bring them indoors. They will finish their eating on the leaves you have there and then because they can’t get off their “island” they will hang in a J (pupate) on the branch – or you might like to add another piece of dead wood in the vase on which they can pupate.

    I’m sure you get the picture, but if you select pretty containers you can make quite a nice table arrangement of it – and will have the joy of watching the whole process.

    However, be careful if you have pest controls in the house – use fly spray or those little plug-in things, as they will also poison your Monarch.

    #25516

    AliaMurray-Smith
    Participant

    Hi NormTwigge,
    Yes I have goggled this & you seem to be right. How sad they seem to be so prevelent in my area. It will take a bit of mangement to save some of the caterpillars that haven’t matured yet. Is there a way of telling when a caterpillar is ready to change into a chrysalis? Or should I just bring them inside anyway until they do?

    #25515

    NormTwigge
    Participant

    Hi,
    From your description the insect is probably Pteromalus puparum, a parasitic wasp that infects several species of moth and butterfly pupae. The wasp was introduced in 1932 to help control the Cabbage white butterfly which had become a pest in New Zealand, so with the build up of white butterflies in Spring comes also the parasite. A Google search on “Pteromalus puparum’ will bring up a host of sites, and photos which should confirm if it is the one you have or not.
    The only way to avoid it is to contain your mature caterpillars in a safe place such as indoors, or in a container such as a Caterpillar castle, that will prevent the wasp from gaining access.

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