Fall is the time of year when male tarantulas, having finally reached adulthood, come out of the burrows in which they have lived for the first 5 to 12 years of their lives. Their mission? To seek out females and mate with them. A host of perils awaits the newly emerged male in the outside world, not the least of which is the female herself.
Female tarantulas are doing what they usually do on warm evenings: sitting in their burrows near the surface, waiting to feel the vibrations of passersby. If the vibrations feel as if they might come from a small animal such as a cricket or another spider, she will rush out, grab the unsuspecting prey item and sink her fangs into it. When a male tarantula approaches the burrow of a female, he first tastes the silk that lies around the entrance. If he detects a mature female in residence, he responds by drumming on the surface with his legs and his pedipalps (the leg-like first set of appendages, which are very long on tarantulas). The reason for this drumming is to let the female know that he is interested in mating -- and would rather not be mistaken for a meal by the larger and always hungry female. When and if a female emerges, he continues to drum as he approaches her. If she's receptive, she will raise up the front end of her body and allow him to grab her fangs with the hook-like projections on his forelegs. He then transfers his sperm to her with his pedipalps.
That was the easy part -- the difficult task still lies ahead: he must release her fangs, disengage himself, and make a hasty retreat before she can overpower him and eat him. Even if he successfully escapes from his big date, the male tarantula is still not long for this world. Adult males (mated or not) usually die before winter arrives.
As if being eaten by your mate isn't enough to worry about, the male tarantula must also be on the alert for predators like owls, skunks, and foxes. If he detects the approach of a hungry hunter, his most effective defense is to quickly use his hind legs to kick some of the hairs off of his abdomen. The hairs dislodge easily and are light enough to float into contact with the nose and eyes of the approaching predator. On contact the hairs produce a burning sensation. This line of defense works well against mammals and birds, but there is another tarantula hunter out there that is an even greater threat, and it is considerably smaller than the spider: it is a wasp called the Tarantula Hawk.
Tarantula Hawks are among the largest wasps in the world; one North American species exceeds two inches in length. They are handsome insects with metallic blue bodies and orange wings, sometimes seen sipping nectar at flowers (particularly milkweeds) in the early evening hours. Female Tarantula Hawks patrol low over open country, searching for wandering male tarantulas or for the burrows of females. When the wasp finds a tarantula, she lands and approaches the spider directly. The spider assumes a defensive posture, raising the front legs and baring the lethal-looking fangs. Unfortunately for the spider, this posture also exposes its underside to the agile wasp, which quickly darts under the spider and stings it in a soft spot where the legs join the body. The sting of the Tarantula Hawk contains a peculiar potion; it paralyzes the spider almost instantly, but does not kill it. The "sleeping" spider is then dragged to a burrow, pulled underground, and buried with a single wasp egg attached to the outside of the body. When the egg hatches, the maggot-like wasp larva has a huge fresh meal waiting for it. The spider is still alive, its tissues undecayed and ready for the wasp larva to devour. The voracious larva will even eat the muscles and other "nonessential" tissue before consuming the still-functioning organs.
So if you are out for a walk or a drive on an early autumn evening and you happen to see a giant hairy spider making his way over the ground, don't react with fear. Just wish him the best of luck. With all the perils ahead of him, he's going to need it.