Home & Garden Columns
Another season has come and gone, and I still have not connected with the tarantulas of the East Bay Hills. Mount Diablo in October was supposed to be a sure thing. So I hiked about a mile up Mitchell Canyon at dusk, scanning the trail ahead for dark objects that might be wandering male tarantulas. (Dusk and dawn are when the questing males are most active, and dawn was not in the cards.) But all the dark objects turned out to be pinecones or piles of horsecrap.
It’s a big deal for the male spiders, their one chance for reproductive success. Male tarantulas mature at about 7, set out in search of a female, mate (or don’t), and expire. Females may live to be 24, surviving multiple partners.
Our local species appears to be Aphonopelma smithi, the Bay Area blond tarantula. Its life history is probably pretty much like that of its relative A. hentzi, the Texas brown tarantula, immortalized by William J. Baerg, an entomology professor at the University of Arkansas, in his slender book The Tarantula. Baerg was the best friend a big hairy spider ever had. “The very general opinion that the tarantula ‘looks so horrible’ is … obviously without any basis”, he wrote. “To anyone who has learned to know this spider, it is as handsome as a goldfinch and fully as interesting.”
He went to considerable lengths to rehabilitate the tarantula’s image.
After his death (not spider-related) in 1980, his colleague William Peck remembered: “Such was his devotion to the tarantula that he considered that all of his students of entomology should at least make its acquaintance.
For some 30 years that he taught beginning entomology he would introduce the students to the large native species by having them pass one from hand to hand around the class. Only one person was ever bitten, he averred, and many a character was strengthened.” Baerg was known to complain of the difficulty of getting tarantulas, or spiders of any kind, to bite him in the interest of science.
Baerg turned his Fayetteville home into a spider sanctuary, with tarantulas wandering the grounds. His lab tarantulas were kept in battery jars, fed on grasshoppers, caterpillars, and cockroaches, and meticulously observed through their life cycles. Once, for whatever reason, he added alcohol to a spider’s drinking water and noted: “Tarantulas will drink of this to the extent that intoxication becomes evident in spite of the eight legs to keep them steady.”
Back to the wandering male: after undergoing his final molt, he spins a special web in the privacy of his den, deposits sperm in the web, and, with repeated dipping motions, charges the bulblike tips of his pedipalps—the pair of appendages preceding the eight legs. And off he goes. How the nearly blind male actually locates the female in her burrow remains unclear.
In a 1928 article, Baerg described what happens when male and female tarantulas meet, after the male has announced himself by tapping out a precise sequence on the collar of silk at the mouth of her burrow: “Frequently when the male has just touched the female with one of his front legs, and she does not show any visible response, he will slap her vigorously several times, which brings prompt action.
She at once rises, spreads her fangs, and the male proceeds.” The female’s fangs are secured by spurs on the male’s forelegs while he transfers the sperm from his pedipalps to her pocketlike spermathecae.
Afterward, whether or not the female appears hungry or aggressive, he disengages very carefully and gets the hell out of Dodge.
That would be just about his last hurrah in any case. Males “begin gradually to fail” after the mating season, their abdomens shrinking away. The female, meanwhile, stores his sperm until the following summer, when her 200 to 800 eggs are fertilized. Her offspring are only 4.2 millimeters long at hatching, but, according to Baerg, they “have a certain unmistakable dignity in their walk.”
Sibling cannibalism is common. The survivors disperse to new homes, digging a burrow or appropriating a ready-made mammal burrow where they’ll spend the rest of their lives—at least until the males are ready to take up their quest.
A tarantula’s venom, although deadly to an insect, typically produces nothing worse than a mild burning sensation and slight swelling in a human victim. Rather than bite when threatened, they’re more apt to dislodge a cloud of barbed hairs by rubbing their abdomens with their back legs; the hairs can irritate a predator’s skin or eyes. Baerg said the hairs caused him only a mild irritation, but his patient wife Eloise had symptoms over a period of several weeks.
So if you happen to meet a tarantula, give him—and it will likely be a him—a break. He means you no harm; he’s just looking for a little action. Let him go on his way, and the ghost of Professor Baerg will smile.