There's an extermination service in my town that sends its servicemen out in pickup trucks with giant plastic black widow spiders on the doors on either side of the car. More than once, one of these trucks pulled up next to me at an intersection and, after glimpsing the outline of a giant black spider out of the corner of my eye, scared the bejesus out of me.

Human beings, it turns out, are more deeply afraid of spiders, scorpions, and snakes than most other things. We learn to be afraid of handguns, because at a rational level, we know these devices are capable of killing us, and we've been conditioned to be afraid. But a fear of spiders is ingrained in people at an evolutionary level. It's wired into our DNA, so that knee-jerk reaction from seeing the spider on our leg comes from the limbic system, automatically, just like touching a hot pan. Just the shape of a spider is enough to speed up one's pulse.

Turns out giant scary spiders are good branding for an exterminator. I hate to encourage this, but if I'm ever unlikely enough to have my place infested with bugs and I need to hire an exterminator, the spider truck guys are the only ones I can think of by name. They're lucky enough to have a business based on something primal, like food or pornography.