Friday, November 20, 2009



Here's my little Orange Dog caterpillar, safely tucked away for the winter.

I realized the other day that my knowledge of caterpillar metamorphosis came largely from The Very Hungry Caterpillar and exceedingly hazy memories of high school Biology, so I'm trying to do a little reading up on what it is that caterpillars do to become butterflies.

I still need to make a trip to the library, where I hope to find a really good book that details the process, but so far, net searching has given me two new facts (That is, facts that are new to me; others probably know perfectly well):

1) A cocoon is not a chrysalis, and a chrysalis is not a cocoon. Cocoons are spun from silk, the chrysalis is a layer of skin hardened; moths do cocoons, butterflies form chrysalises, so that's what this guy was doing all those days he seemed to just be sitting there shrinking.

2) Butterflies--some? all?--spend some of their time in the chrysalis as a sort of biological soup. No one is really sure how the creature gets from caterpillar to DNA soup to butterfly. That is pretty amazing!
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  1. Actually, both moths and butterflies form chrysalises, moths just spin the cocoon around themselves first. Butterfly larvae just spin the little silk anchor that holds them onto whatever surface they're sticking too. Then they moult their caterpillar skin, and pupate. Since this is one that orients upwards, he probably has a little silk rope around the middle to hold him that way.

    A lot of insects have pupa stages. Flies and beetles do as well, as opposed to the insects where the juveniles look very similar to an adult, just smaller (often called nymphs).

  2. Both form chrysalis? Neat!

    The soup part still blows me away. I guess I'd pictured the change from one stage to the other as being like tadpole to frog: Gradual changes only inside the cocoon.

    (And I take it the pupal stage=the "soup stage"?)

    Do you happen to know if Neem oil would hurt him? I usually spray the orange tree with it, and it is definitely healthier if I do, but I don't want to hurt "my" swallowtail.