The Wild File


Q) Why do we still see caterpillars in the fall? Shouldn't they be butterflies by now?

Nancy Lynn Cole, Green Bay, Wisconsin

A) Most species of moths and butterflies—a.k.a. Lepidoptera—hatch in late spring, crawl about as caterpillars all summer, pupate in fall and winter (they're called cocoons if they're moths, chrysalises if they're butterflies), and emerge as adults the next spring. But there are caterpillars that roam the earth year-round, with each of the 112,000 species following its own savvy DNA-programmed schedule. According to University of Illinois entomologist Philip Nixon, lepidopterans are highly adaptive creatures that have evolved to take precise advantage of conditions like weather and the waxing and waning of their host plants. Consider the Isabella tiger moth, seen from coast to coast. In late summer, its eggs hatch into woolly bear caterpillars, which spend the fall munching lamb's-quarters and other plants. In the winter, when food is scarce, the fuzzy fellas hibernate, only to cocoon in the spring and emerge in early summer as adults. The complexities go on. Some moths produce multiple generations in a year, so you might see their offspring at any time. An example is the magnificent monarch; its caterpillars eat only milkweed, the pursuit of which (along with cold temps) spurs the butterflies to make their annual 3,000-mile migrations up and down our continent.

Q) Why do we say "Geronimo" when we jump?
Marian Miller, Santa Fe, New Mexico

A) We humans like to yell battle cries before entering the fray—be it bona fide war or a cannonball off the high dive—as a way of raising our confidence and unifying the ranks. This particular utterance dates back to 1940 and a U.S. Army paratrooper named Aubrey Eberhardt. On the eve of the Army's first mass parachute jump, at Fort Benning, Georgia, he and his platoon watched a B-grade western called Geronimo, about the 19th-century Chiricahua Apache chief. Private Eberhardt was inspired by the fierce warrior and told his buddies he was going to shout "Geronimo!" when he jumped the next day, to get out the jitters. He did just that, followed by a war whoop. The others did the same, and soon the cry was being heard all over the skies above Normandy—and at swimming holes all across America.

Q) What makes the moon look bigger at moonrise?
Philip D. Armour III, Kaneohe, Hawaii

A) You've hit on a curiosity that has stumped many lofty thinkers, and probably most of the hot dates you've ever moon-gazed with. It's called the moon illusion, and it's just that: a trick on your eyes and brain. Most viewers perceive the full moon on the horizon to be 50 to 75 percent larger than it is at its zenith, but the orb is the same distance from Earth at both points. Scientists have hundreds of explanations, with many still clinging to a notion Aristotle put forth around 350 b.c.: that the image of the horizon moon is magnified by our lenslike atmosphere. But a father-son team, retired NYU psychology professor Lloyd Kaufman and IBM physicist James H. Kaufman, did a series of experiments in 1999 that they say confirm the "apparent distance" theory, suggested by Ptolemy in the second century and formulated by Arab physicist al-Hasan 900 years later. It involves the brain's distance-gauging mechanism, which constantly adjusts to make the images we view jibe with the reality we know is there; the brain can't make these "rescalings" without using an object's surroundings as a guide. When you see the horizon moon, your mind takes into account the terrain in front of it and concludes that it's really far away and, therefore, really big. When the moon's overhead, the cues are gone, and the visual center in your brain is unable to assess its distance (it's 249,000 miles away, after all) and thus can't determine its size. Neurophysicists are working to prove this once and for all, but for now, score one for the Ptolemeister.

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