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Friday, October 1, 2010

not what it seems





I’ve heard from several people that believe this has been a very good year for butterflies. Whether it has been a good year or a lean year is hard to determine, but nature does have pulses. One day you’re up, the next you are down; it’s a lot like politics, just ask Newt Gingrich.

This photo comes from my friend Jackie Kittrell. On first glance you might think that it’s one of those beautiful swallowtails, but which one?

That is what it wants you to think, or better still, that is what it wants the butterfly-eating birds to think.

The top photo shows a red-spotted purple (Limenitis arthemis), It's one of the brush-footed butterflies common in our region. (Don’t look too hard for the red spots in the photo, they are found on the underside of the wings.) The tops of the wings are noted for their iridescent blue markings.

But, here is where it gets interesting: the red-spotted purple is a mimic of the poisonous pipevine swallowtail (Battus philenor), a blue butterfly that feeds on pipevines (Aristolochia species, including A. californica, A. serpentaria and others) when they are caterpillars. These host plants transfer a toxic quality to the larvae and resulting adults.

If a bird eats a pipevine swallowtail (bottom photo), it gets sick, so it never eats another or even a butterfly that looks like it, so the mimic red-spotteds go unharmed. It’s like that greasy-spoon diner out on Highway 11; if you eat there once and hurl your hash later, you are not likely to go back.



Pipevine swallowtail, a.k.a. greasy-spoon diner



- Top photo by Jackie Kittrell. Thanks, Jackie


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