Earth Almanac: July/August 2009

Chiggers Suck

If you live anywhere from southern New England to California but not much north of the latitude of Nebraska, early summer is the time to look for chiggers. If you’re lucky, you won’t find them. Chiggers are the six-legged, parasitic larvae of eight-legged harvest mites—those scarlet, spiderlike creatures you see scurrying away when you turn over your garden. You’ll perceive chiggers only by feel—they itch mightily—because they’re no more than 1/120th of an inch long. What you will see are the red welts they leave in such sensitive areas as armpits, crotch, and backs of knees, and under tight-fitting garments like belts, bras, socks, and underpants. You’re a second choice; they’ve settled for you only because they didn’t find a quadruped mammal, reptile, bird, or amphibian. Bug repellents will discourage chiggers, and washing after exposure will remove most of them. We have it from all manner of sources that chiggers burrow into human flesh and drink blood and that, therefore, the best way to kill them is to suffocate them by applying nail polish to the inflamed area. It’s hokum, not that the truth is any nicer. A chigger injects digestive enzymes that liquefy your skin cells and at the same time harden the surrounding tissue into a strawlike feeding tube that helps it suck up its meal. When the chigger is fully engorged, after about four days, it drops off and transforms to a nymph, which, in turn, transforms to an adult harvest mite. In partial atonement for their misspent youths, the non-parasitic nymphs and adults eat mosquito eggs.

Slip-sliding Away

When summer sun heats the sandy washes and hardpan flats of the Sonoran, Colorado, and Mojave deserts to temperatures that could blister human feet, the petite sidewinder keeps its cool. Now this little rattlesnake, rarely more than 30 inches in length, hunts mostly by night, seeking refuge during the day in rodent burrows whose former occupants have likely provided it a repast. It ambushes small mammals and lizards by burying itself in soft sand. When it does venture into the heat of the day it “tiptoes” at high speeds, hurling its body sideways in lateral waves so that only two short sections touch the ground. Its tracks are distinctive—J-shaped loops with the hook of the J pointing in the direction of travel. The hornlike protuberances above each eye that give the sidewinder the alternate name of “horned rattlesnake” possibly provide protection for the eyes when the snake is negotiating underground burrows.