Catepillars are nature's slowest cannibals.

Tomato plants defend themselves by emitting a chemical that hungry herbivores find toxic, unappealing, or difficult to digest. Scientists recently learned it also makes catepillars prefer to eat each other, if ever so slowly.

The caterpillars gave up on the tomato leaves early. And like desperate characters in a cartoon island mirage, fellow caterpillars became appealing steak dinners. “You start the experiment with eight, and you end it with one or two,” said Dr. Orrock.