100 years ago: woolly bear caterpillars obey the law

Originally published in the Manchester Guardian on 4 September 1917

September 3
"Woolly bears," in a fearful hurry, race across the road; they look as if they meant business or feared the wheel of passing vehicle or heedless boot. But the caterpillar knows nothing of danger, but merely acts as heredity has taught it; it must obey laws or go under in the struggle. Most insects need a wide distribution, for too restricted a feeding area may bring famine or degeneration; in one or other of their stages insects must get to a distance from congested districts or from ravaged food-plants. Naturally this distribution or migration takes place with many insects when, in their perfect stage, they are provided with wings, but some moths are slow-flying and lethargic, too busy with nectar-sipping and egg-laying to travel far, and in these the caterpillars make the journeys, getting over as much ground as they can before they find it necessary to spin cocoons.

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