Ants are a pest…

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  • #14577


    Thanks to all of you for your reports of sightings of pest ( – they’re very helpful in keeping us informed about what’s going on in the world of butterflies (and moths!) around the country.

    This one in today from Waikane:

    "Our 1.70m swanplant has all its leaves eaten and the remaining caterpillars are now eating the swans.

    Few chrysalides ever appeared on the plant and the few there are now are being attacked by small black ants by opening the bottom point. They seem to suck the fluid leaving a comb of firmer tissue.

    Have there any recent reports made of this damage?"

    Comments please.

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  • #25926


    I only had this problem last year. It only happened once or twice but as soon as the caterpillars had formed their chrysalis – and still soft – the ants would come and eat the whole thing – very, very quickly. It was disgusting. At first I didn’t know what it was then I watched and realized it was ants.

    This year we still have ants – but they haven’t eaten any chrysalis’ just the nectar from the flowers. Last year, I put vinegar around the pots to repel them and it worked. I also got a plant from the garden centre said to repel ants, seems to work, can’t remember it’s name though. It spread out with purple flowers.



    I had an ant incident yesterday. A caterpillar had gone into its J , a little early I thought ~ and I isolated it and put it into a jar on a ledge . Next thing i noticed was that as it was going into chrysalis, ants were all over it. They were definitely ants. Perhaps the chrysalis was a ” “malfunction ” anyway and the ants were just doing their job.

    I have also had quite a few caterpillar deaths in the last few days and am combing my leaves and branches for what it could be. I found one small black beetle with yellow spots, and a tiny mantis. But still 3 more dead uns this morning. You have to be very careful inspecting the foliage that you put the caterpillars on, when using clippings from plants grown outside . !!



    It is quite usual for mature caterpillars to leave the plant when ready to pupate, and have been recorded travelling many metres to do so.
    I would check with a magnifying glass to make sure the black ants are in fact ants, they could well be the tiny parasitic wasp Pteromalus. It is unusual for ants in NZ to attack the living chrysalis, but if the chrysalis had died then ants will utilize it for food.
    Photographs sent in are always a help to pinpoint any problems.

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