Earth Almanac: May/June 2008

Moon Flakes

Nothing imparts more magic to a late-spring evening than the appearance of a luna moth. Perhaps it clings to your porch screen or dances fairylike around a streetlight, or maybe you catch its shadow as it flutters across its namesake’s bright face, long tails tossing in unstable, seemingly impossible flight. Older insect guides report that these four-inch-wide moon flakes are fading from the American scene, rare to the point of endangerment. But throughout most of their range, from the East Coast to the Dakotas and Texas, luna moths are now common. It’s just that they are rarely seen because adults live only for about a week. As with other giant silk moths, their digestive tracts have disintegrated during pupation, so they don’t eat. Basically, they’re flying gametes. When darkness settles the female releases a pheromone detected at great distances by the male’s antennae, more feathery than the female’s. The females deposit eggs on such plants as walnut, butternut, sweet gum, paper birch, persimmon, alder, beech, and willow. Find one of the light-green, dark-headed, yellow-striped larvae on any of these host plants, and enclose it with netting to protect it from predators. Make sure to leave plenty of space for it to feed. Next spring check the cocoon regularly.

Cuckoo Come Lately

In late spring, when almost all other birds are incubating eggs or feeding hatchlings, yellow-billed cuckoos breeze in from Central and South America to set up housekeeping in old orchards, thickets, and shrublands in the eastern United States and isolated locales in the West. It’s a hurried job, sometimes taking as little as 17 days from egg laying to fledging. One day the quill-covered nestlings look like porcupines, and flight seems out of the question. The next day feathers burst forth, and the birds take to the air. Occasionally, the process is so rushed that nest building is skipped and the female drops her eggs in another bird’s clutch, though the surrogate parents are usually other yellow-billed cuckoos. Such behavior may be less Old World-cuckoo nest parasitism than “brood cooperative” egg dumping. Yellow-billed cuckoos eat fruit and all manner of insects, including hairy caterpillars that repulse other birds, and they are among the very few North American birds capable of preying on gypsy moth larvae. When their stomachs get so perforated with spines that digestion is impaired, they merely regurgitate the linings and grow new ones—“a process,” noted early 20th century ornithologist Edward Forbush, “that would be beneficial to some unfeathered bipeds could they compass it.”