Caterpillars of the European cabbage butterfly, which has invaded most of North America, turn out to bristle with a kind of defense system that scientists have not documented before.
The caterpillars sprout hairs that carry droplets of a novel predator repellent derived from a fatty acid, says Thomas Eisner of Cornell University. Ants tend to avoid the caterpillars or spend an unusual amount of time cleaning themselves after contact, Eisner and his colleagues report in an upcoming issue of the Proceedings of the National Academy of Sciences.
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