I detest household bugs. Abhor them. There isn’t a word strong enough to describe how I feel about bugs in my home.
That hatred provokes guilt, because I fancy myself an environmentalist. As such, I’m supposed to feel a kinship with all creatures. We’re connected in a circle of life, a colorful tapestry, a delicate web of interdependence. But I can’t help it: My love of animals doesn’t extend to cockroaches, bedbugs and their ilk. So I’m on a mission to prove that, in the vast family of 8.7 million species on Earth, there are a few that we could do without.
Consider the cockroach, that most hated human pest. If we could render it extinct, would anyone — human, animal or plant — mourn the loss?
“Roaches in general get a bad rap from the 1 percent of cockroach species that infest our homes,” says Coby Schal, a professor of entomology at North Carolina State University who studies the little buggers. “Most of the 5,000 known species of cockroaches, plus probably just as many that have not been described, have huge ecological importance.”
Cockroaches can be found almost anywhere that supports life. The microbes in the bellies of forest roaches break down leaf litter and other plant materials that are indigestible to many mammals. They are pollinators in the tropics. Desert lizards feed on roaches. In the Southeastern United States, Schal notes, cockroaches constitute more than 50 percent of the diet of the endangered red cockaded woodpecker, a small, black-and-white bird with a red spot behind the eye of males. If these roaches disappeared, the birds and lizards that feed on them would suffer, and some might plummet dangerously close to extinction.
Fair enough. But what about those pesky roaches that run nightly riot in urban homes?
“I don’t see any great ecological value to them,” Schal says. “Most of the cockroaches in homes are German cockroaches, or sometimes American cockroaches. With a few exceptions, they live almost exclusively among humans.”
(A terminology note: The German cockroach isn’t from Germany, nor is the American cockroach a New World native. Carolus Linnaeus, the father of the binomial naming system, was given specimens from those areas and named them accordingly. Roaches probably emerged from East Africa or Southeast Asia.)
Before deciding to magically render extinct German and American cockroaches, we might pause to marvel at their adaptation to human-dominated environments. They can live in broad temperature ranges and survive for weeks without food. They can eat almost anything, from spaghetti to steak, whereas other insects specialize. They have a waxy coating that prevents them from drying out in heated or air-conditioned environments.
The dangers of cockroaches are often overstated. Cockroaches do carry bacteria: Fecal matter adheres to them, they ingest it during grooming and they defecate it, sometimes onto human food sources or food-related equipment. Nevertheless, Schal says, few studies have conclusively shown that roaches regularly transmit disease to humans. In fact, their main danger to people is the production of airborne allergenic proteins that are inhaled by people. Urban children sometimes suffer asthma or allergy attacks from roach exposure.
The verdict on cockroaches? It’s unanimous among the entomologists I spoke with, at least for German cockroaches: We could safely eliminate them. They are so exquisitely adapted to life with humans that they fill no other ecological niche.
So what about bedbugs? If you’ve never faced a bedbug infestation, count yourself lucky. Their bites can cause enormous welts, and getting rid of the little critters is an ordeal, especially since some of the chemical agents most effective in combating them have been banned as environmental toxins. Is there anything nice to say about bedbugs?
“Some species of ants feed on bedbugs, as do a few spiders,” says Michael Potter, an urban entomologist at the University of Kentucky. “We often find them caught in spider webs in dwellings. But is that the spider’s primary source of food? Would the whole system come crashing down without them? I doubt it.”
The frustrating thing is that we have already beaten back bedbugs once, at least in the United States. When international travel increased in the 1990s, Potter notes, these insects returned to our shores from Africa, Asia, the Middle East and parts of Eastern Europe. We’re partially culpable for their return. People used to prophylactically treat their mattresses and checked hotel beds when they traveled, but those habits faded. We also stopped developing new treatments to poison them, and bedbugs have become resistant to established methods.
Like the German cockroach, the common bedbug lives almost entirely among humans, and the entomologists I surveyed all agreed with Potter that, if they could, they would wave a magic wand and eliminate bedbugs. (“I’d wave it twice, just to be sure,” says Micky Eubanks, an insect ecologist at Texas A&M University.)
When asked the more general question about which pests could safely be destroyed, Eubanks developed a theory: Species living in their natural ranges at normal concentrations must be tolerated. Those living outside their ranges at excess abundance can at least be reduced if not discarded. (The German cockroach, for example, has no native range aside from our homes.) In between, there is a balancing act to be done.
He points to the Colorado potato beetle as an example. This insect is native to the New World and used to feed on a wild relative of the cultivated potato. When potato agriculture entered into the bug’s natural range, the population exploded. It would be nice to reduce them, but take away too many and other creatures, such as parasitoid wasps that feast on them, would clearly suffer. You may not like wasps, but the loss of them would affect other predators, and a chain reaction would begin.
Mosquitoes are another tricky case. No creature is more dangerous to humans: Mosquito-borne illnesses kill more than a million people annually. But they are an important part of the ecosystem.
“Mosquitoes represent a significant biomass of food for other species,” Potter says. “In places like Alaska, you get a huge emergence of adult mosquitoes when the temperature rises, and they are an important source of food for migratory birds and other critters.”
Destroying mosquitoes might be risky, but I’m feeling much better about my willingness to get rid of German cockroaches and common bedbugs. It seems that some branches of the tree of life can be trimmed back a bit.