Tarantulas and Tarantula Hawks: A Duet to the Death

One autumn evening a decade ago while watching TV in our living room, I glanced down at the floor, where one of our cats was stalking a huge, hairy spider. That was my introduction to one of the twenty-plus Southwest species of the tarantula, and it was a little too close for comfort. My husband carefully scooped it into a plastic cup and transported it to our outdoor woodpile. For a while after that, I was checking the insides of my shoes every morning. I'm no arachnophobiac, but I tend to give a spider that big a wide berth.

Mine is a common albeit unnecessary reaction to Aphonopelma chalcodes, the largest arachnid in North America at three inches in length and a leg span of six inches. Compared to other spiders, it lacks anatomical complexity. Its size, hairiness, and long, fearsome-looking fangs, not to mention the two furry patches of eight virtually sightless black eyes in front of its body, make it a candidate for monster hood. But its venom is harmless to humans, and it won't bite unless roughly handled. It can also release tiny, irritating hairs on its abdomen when upset that are harpoon-shaped and cause pain in some people, none in others.

For smaller animals, however, a run-in with a tarantula is a different story. The tarantula's 1/4-inch fangs bite and release venom plus digestive fluid which liquefy the soft tissues of insects, small lizards, and other tarantulas. The spider literally sucks their bodies dry and leaves an empty shell behind.

Since my first encounter, I've run across tarantulas-sometimes the black male but most often the yellowish female-in many places, but all thankfully outside. In autumn their silk-lined burrows can be seen all over the ground. They're generally nocturnal, although I often come upon them lumbering slowly overland during the day. Tarantulas hunt with no obvious plan, sniffing, tapping about, or simply waiting inside their burrows, only to rush out and pounce on hapless prey. They actually "see" through smell and touch; their hairs pick up vibrations. They can taste with the tips of their palps and feet and through openings on their legs.

The burrow of the tarantula serves as a place of hibernation in times of drought and cold. The entrance is plugged and the spider becomes dormant. It can survive without eating for over two years, and without drinking for seven months. That's a useful talent in this dry desert climate.

Fall is mating season for tarantulas, sexual late bloomers who mature at 8-9 years old. The males cruise for mates after sunset or near dawn. Once they locate a female, they tap the ground, which is intended to entice her. If she's sufficiently aroused she raises her body and displays her fangs. The male gingerly grasps the fangs with the spurs on the sides of his front legs. This maneuver disarms her, whereupon he inserts a seminal fluid-soaked limb into her genital opening. After a few minutes he withdraws and seeks another mate. After only one energetic mating season, male tarantulas die. Females can survive up to 30 years in captivity, making them the longest-lived terrestrial invertebrates.

In spring, each female lays a cluster of 500 to 1,000 eggs, wraps them in a cocoon, and hangs them in her burrow. The spiderlings hatch about a month later and leave the burrow within two days. Not many make it, however. They're a favorite food of scorpions and roadrunners. And if tarantulas manage to survive to adulthood, the tarantula hawk hunts and tries to parasitize them in what is one of the slowest, most torturous life and death rituals in nature.

Tarantula hawks are large indigo black solitary wasps with lovely black, red, or orange wings that live in the lower elevations near tarantulas. After mating, female hawks search for tarantulas to feed their larva. Nobody knows why these wasps are able to capture their venomous prey, who could easily kill them; and why tarantulas often just stand around in apparent cooperation before they're stung. Do the wasps cast a hypnotic spell with some kind of chemical they emit? Is it their pattern of touching the bodies of the tarantulas that immobilizes the spiders? Do they mimic the sexual advance of the male tarantula?

At any rate, after the wasp locates a tarantula burrow, she somehow lures the spider out, climbs on his back, thrusts her 1/2-inch stinger into his abdomen, and paralyzes him. She then drags the comatose spider to her burrow, lays an egg on top of him, and seals the burrow. After the larva hatches, it finds a ready food supply, devouring the spider in a few weeks. To keep him alive, it leaves the major organs for last. A comatose tarantula can live for nine months, although it generally doesn't. The larva grows-thanks to the tarantula food-and then pupates, metamorphosing in spring into an adult. If the adult is female, she immediately sets off to continue the ghoulish cycle of survival. The tarantula hawk's sting is said to be extremely painful to humans. So compared to the relatively benign but scary-looking tarantula, the handsome tarantula hawk is a creature to respect-and avoid. In nature, appearances often deceive. But even so, I'll continue to give tarantulas all the space they deserve.