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Monday, April 2, 2012

Clever little caterpillar!

I've been documenting the development of Spicebush Swallowtail caterpillars on my recently planted spicebush. It only took the butterflies a few short days to find it and begin laying eggs on it.

Here was one of several tiny eggs that I found on the bush after watching a female swallowtail visiting it.

A few days later, I discovered that the eggs had hatched and I found seven of these little guys on various leaves. They bore a striking resemblance to bird poop and each was motionless on its leaf, obviously an adaptation to protect the newly-hatched caterpillars from the notice of predators.

Today when I stopped by to check on the caterpillars, I immediately noticed that several of the leaves had been nibbled and folded over. Examining the folded leaf, I found it was stitched together with a kind of silk and that there was a tiny Spicebush caterpillar inside the pocket that was formed.

Back inside, I pulled my John and Gloria Tveten field guide, Butterflies of Houston and Southeast Texas, from the shelf to read about the Spicebush Swallowtail. The Tvetens had written, "The larvae feed primarily at night, hiding during the day within a rolled leaf stitched with silk." So my caterpillars were performing exactly as Spicebush Swallowtails are known to perform. I had just never seen it because I've never had Spicebush caterpillars before.

Caterpillars are easy prey for hungry wasps and other predators and so they have to develop defensive measures to protect themselves. The rolled leaf is one of the most effective and it is used by several types of caterpillars, most notoriously the "leaf-rollers" that make a mess of our canna leaves during summer. Pretending to be a bird dropping is another defense. The clever little Spicebush caterpillars use both of these strategies and no doubt increase their survival rate accordingly.

4 comments:

  1. I also grow Spicebushes in my gardens as host food for the Spicebush Swallowtails.....
    I love watching the cats and the chrysalis and the butterflies....
    Sherry

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    1. This is my first experience with them, Sherry. Fascinating critters! I must add more spicebushes to my garden.

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  2. Nancy B's GardenApril 3, 2012 at 5:01 PM

    Birdwoman,

    Congratulations on your swallowtails! I would love to have them in my garden also.

    Life is such a balancing act and so is gardening. Since I don't have a huge amount of space left in my yard, I'm having to pick any future plants very carefully. I am reading conflicting information on spicebushes. What are the sun requirements and what it the bush height at maturity?

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    1. According to the information I got from Arbor Gate where I bought mine, Nancy, the spicebush can get from 5' to 8' tall and wide. It is often wider than it is tall. It will grow in full sun but probably prefers partial sun to light shade. Mine presently is in full sun. If it doesn't seem happy there, I can always move it next winter. After all, moving plants is what I'm famous for.

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