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Desert Diary

Arthropods/Why A Butterfly?


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Why a butterfly? Why not just the worm-like caterpillar? Or, you could turn around the question and ask why the caterpillar when there's a perfectly good butterfly? Actually, there's an excellent reason for having both forms. A creature specialized for a task usually is far more efficient than a generalist that needs to do everything.

In the case of moths and butterflies, we have two specialists for the price of one. The caterpillar stage is an eating machine, and very good at it. Its job is to stuff itself, storing energy garnered from its plant prey. Despite its efficiency at this, it's absolutely incapable when it comes to reproduction. That's the job of the butterfly form. Not only does the butterfly have the reproductive organs lacking in the caterpillar, but wings—wings indispensable for dispersal, for finding plants to lay eggs on so that the next generation of caterpillars are able to gorge themselves. Of course, some butterflies also can sip nectar, giving that little extra boost of energy. Successful? Some 130,000 species say, "You bet!" pen and ink


Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.