Monarchs and biodiversity

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  • #51682


    Yes, we love our monarchs. But should they be given any more special treatment than other flora and fauna?

    Well, let’s do a little bit of maths. A female monarch can lay 300 or 500 or more eggs (one female laid 1179!) Let’s be conservative and say the first female monarch in our garden in spring (September) lays 300. Let’s say there is plenty of milkweed (e.g. swan plant) and no predators, parasites or anything to stop these 300 eggs becoming adults.

    So in October there will be 300 monarchs flying around, of which some 150 will probably be egg-laying females. Multiply 150 x 150 and in November the number would be 22,500.

    In December, 3,375,000.

    In January 506,250,000. February 75,937,500,000. In March 11,390,625,000,000.

    Are you following this?

    While we all love monarch butterflies, there will be ‘boom’ and ‘bust’ periods in their life cycle.

    In 2017 in many parts of the country there was a long, wet winter. Swan plants died. Snails and slugs proliferated and fed on many of the healthy swan plants, killing more plants off. In the spring only a few swan plants had survived.

    We’ve had reports too of low numbers of wasps – presumably the winter knocked a lot of their nests out. Which is why right now there is a boom period of monarch butterflies/caterpillars.

    This is entirely natural!

    Not every monarch is destined to become a beautiful butterfly. Some will become food for other species – even food for the soil.

    Where there are too many monarchs it becomes a perfect breeding ground for diseases and other organisms which will kill off weaker caterpillars. This too, is entirely natural. The boom and bust of Nature at work. When there are no caterpillars the swan plants have a chance to recover.

    The amazing thing about monarch butterflies is besides being a beautiful addition to the garden, in their life and death they teach us so much about biodiversity.

    I’m not saying that we shouldn’t be trying to find food for monarch caterpillars… rather we should put it into perspective and understand what Nature is trying to tell us.

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  • #51843


    Thanks Lesley.

    Rob, yes there will be boom and bust periods. From what you say it is a “bust” or low point in the cycle, and your intervention will certainly help raise the numbers. Good on you!



    rob cooper

    thats not really true jaqui we all have our own thoughts and see things as we do nelson has been so knocked back by the paper wasp not many butterflies i go out of my way to help them yes i no where you are coming from but dont put people off in bad places with very few monarchs to help them out i so help but also keep a eye out on my plants yea lots of pillers time to cull some eggs keep the plant ok for maybe our winter ones



    Good point Jacqui .. I’ve long since come to the conclusion I had to toughen up and be realistic or the whole thing was just too upsetting.

    My approach this year is to grow and provide as much swan plant as I can and take reasonable steps to help the critters along. But end of day my success rate (caterpillar to butterfly) is about a third .. if i’m lucky, whatever I do.

    I had them in a hothouse last year because the weather was so abysmal here and while it basically kept the same level of success (one third) I noticed disease creeping in.

    When I bought the autumn stragglers inside only a third of the caterpillars made it to a pupa and then only a third of those emerged. Not one butterfly returned to lay eggs in the new season and I had to take immigrants :).

    Bottom line is we can’t beat nature so IMO its best to just recognize that and enjoy things for what they are.

    Merry xmas everyone 🙂

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