Monarchs/Oe/California

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This topic contains 2 replies, has 3 voices, and was last updated by  NormTwigge 5 years, 4 months ago.

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  • #39238

    Jacqui
    Moderator

    Hello all

    A “learned American” has posted the following (in italics) in another forum. I would be interested in hearing other people’s comments!

    Jacqui

    —————

    I believe the reasons monarch enthusiasts in New Zealand
    and Australia have never (to my knowledge) entertained the thought
    of cutting back their evergreen Gomphocarpus milkweed to near
    the ground on a landscape scale during the winter months are:

    1) Thousands (collectively) of monarch eggs / caterpillars /
    chrysalids that were eating those milkweeds at the time of cutting
    during the winter would be killed outright or subsequently starved.

    2) The small number of female monarchs that develop eggs during
    the middle of winter and the huge number that develop eggs in late
    winter would find a greatly deminished biomass of milkweed
    foliage available due to the midwinter cutting. Plus there would be
    alot less milkweed foliage available for the caterpillars to eat. Thus
    the monarch migratory population could be expected to greatly
    decline.

    Would that serious monarch population decline be worth the minor
    butterfly health benefit of a reduced OE infection rate? I say
    “minor” because I am unaware of any study that has shown the
    OE parasite kills / deforms / cripples a high percentage of migratory
    monarch caterpillars / chrysalids / newly emerged adults under
    real world natural field conditions.

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  • #39241

    NormTwigge
    Participant

    I suspect the American enthusiast may live in an area that has mild winters, as normally
    1. monarch larvae do not generally survive the winter here.
    2. egglaying does not normally occur during the winter.
    I say normally, as last year I had a monarch laying eggs in July, but the eggs never hatched.
    Because of the geographical differences there are many situations that do not follow the U.S. here in New Zealand.

    #39239

    Caryl
    Participant

    But this variety are frost and wind chill tender and in I would say most areas of NZ don’t survive the winter and in Wellington where I am I have had 20 or so plants die in the past few weeks due to the wind chill factor – not from frost although the ground temperature could be colder than the 3 degrees C measured in Wellington this morning. I have used a weak bleach solution successfully and think it’s a good idea to spray each purchased swan plant of any variety but of course not if caterpillars are present. I certainly have had a higher butterfly fatality rate in the past couple of months than earlier in the season. Many did not do well in the gales and heavy rain we had and many chrysalises were deformed.
    Also I believe most people would check for eggs, caterpillars and chrysalids before cutting back any swan plants. There are no eggs on my plants now and only a few hardy caterpillars. Apart from a few butterflies I tagged and released in the past month I have seen no monarchs flying for weeks. The earliest eggs I have had were in early August which took more than 77 days to eclose due to the low temperatures.
    http://www.butterflyfunfacts.com/pupae-flaws.php

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