The black spider crept across the basement floor, venom glistening from its deadly jaws. While the unsuspecting heroine rummaged through some boxes, the spider crept closer, and yet closer, until…
It’s a familiar scenario for a scary movie, but there isn’t much truth to the image of the malevolent black widow stalking its human prey. Yes, these spiders are venomous, and yes, they can bite us and do damage. But Black Widows really need a new image. They’re actually shy and retiring creatures who desperately want nothing to do with us humans.
I live in Colorado, where Western Widows (Latrodectus hesperus) are fairly common. I’ve found them in the house (I really need to clean under of the bathroom sink more often!) and in the backyard storage shed/greenhouse. They particularly like the damp space under rocks and logs, or in the buried box that holds the sprinkler valves. There they build their large webs and lie in wait for insects and other small arthropods.
I admit I screamed the first time I encountered one of these distinctive spiders. Then I attended an outstanding lecture given by arachnologist Paula Cushing, Curator of Invertebrate Zoology at the Denver Museum of Nature & Science. I began to realize how fascinating spiders can be. Dr. Cushing explained that she’d held black widows many, many times, and had never been bitten. Apparently, this is typical widow behavior. Catherine Scott, an arachnologist at Simon Fraser University in British Columbia, Canada, described her experience:
“In most cases, poking the spider repeatedly with a finger wasn’t enough to get the arachnid to bite, the researchers found. Instead, the prodded black widows in the study often ran away, played dead or flicked a few strands of silk at their attackers.”
To start with, only the females are venomous. Then, the only time she bites is when she’s in danger of being squashed—and even then she doesn’t always inject venom with her bite. Even if you do get bitten, the bite is unlikely to be fatal. A trip to the emergency room will provide you with an antidote, but even untreated, most people recover in several weeks.
I realized that I had to rethink my attitude toward a helpful spider that eats flies and mosquitoes!
We all know that black widows get their name from the female’s habit of eating her mate after sex. Well, even that “fact” isn’t always true. A male (left) approaching a female does an elaborate dance to identify himself as “fun, not food,” and sometimes she takes the hint. Of course, other times she doesn’t—being a male black widow is still a high risk occupation. Why mate with someone who is going to murder you? You’d think that the males would avoid the females, and that this species would have died out long ago!
Surprisingly, for a male, being eaten during copulation has an advantage. Males who die during sex leave behind more sperm. The female then stores these sperm and uses them when laying future eggs. As a result, these males pass on more of their genes—the goal of any species. It just happens that they do it posthumously. (For more fascinating information on black widow sex, see this National Geographic article.)
So black widows are not the baddies that the media makes them out to be. Still, I doubt I’ve convinced anyone to invite them into your homes. In that case, you might be happy to learn that there is a species of wasp that specializes in eating them! Yup, the Blue Mud Dauber is happy to patrol your yard for these and other spiders, and gobble them up for you.