We are not alone.
No, that's not the title of the latest book on UFOs. It's a statement of fact recently proved by some intrepid entomologists from North Carolina. For the first time, these scientists managed to quantify the number of arthropods we humans can expect to have living with us in our homes. The number comes to just under 100 per household. That's 100 different species, not just 100 individual bugs running around.
They took specimens from 50 homes in and around Raleigh and found 579 separate species of invertebrates. The most common species belonged to order Diptera (flies) followed by arachnids (spiders), coleopterans (beetles), hymenopterans (mostly ants) and psocodeans (silverfish). These five groups made up 73 percent of all the specimens collected. There were four families of arthropods that were found in every house: ants, carpet beetles, cobweb spiders and gall midges. Book lice and fungus gnats were found in 98 percent and 96 percent of the houses, respectively.
I suppose it shouldn't be surprising that there are 579 (and that's a conservative estimate) species of arthropods hanging out with us. After all, they've been in, on and around us since we managed to evolve into our current morphology.
It's just that I'm not living in some primitive hovel or cave. Like most of us, I feel that my house is relatively clean -- and it is, despite what my grandchildren attempt to do to it. Yes, there will be the occasional mosquito, roach or spider wandering through, and a pet may bring in some fleas or a tick or two. The limes I bought to use in my Key lime pie recipe may have some fruit fly maggots ready to emerge and a curious queue of ants might be scurrying through my kitchen cleaning up that bit of sugar I spilled. But 579 different species? That's a bit much even for me, and I'm one of those people who like creepy crawlies.
Oddly, what we would consider typical household pests were in a distinct minority (eg. German cockroaches, 6 percent; subterranean termites, 28 percent). For that matter, most of these creatures are tiny, even as adults, which means that you probably wouldn't even know they're there. Yet, even though over 90 percent of the species collected cause no direct harm to us or our property, many people would consider them pests merely because they are in our homes.
Fortunately for us, but not for them, our dwellings are severe environments for the vast majority of things that come into our homes; the temperature is wrong and the humidity is way too low. Most will be dead from dehydration within a few days, so, there's no need to panic and start unleashing bug bombs or calling the exterminator. Just relax. After all, who doesn't like a little company?
Tim Lockley, a specialist in entomology, is retired from a 30-year career as a research scientist for the U.S. Department of Agriculture. For answers to individual questions, please send a stamped, self-addressed envelope to Tim Lockley, c/o Sun Herald, P.O. Box 4567, Biloxi MS 39535.