This article originally appeared on Tonic.
Ah, friends. They're like family but cooler. Fully customizable. Fall and one of them will be right there to pick you back up. But as great as friends can be, they also do a lot of really stupid stuff. Stuff that blows your mind. Like, sometimes it seems crazy that you even hang out with people who make such crappy decisions. Stuff that, were it to get out, would be mortifying for anyone with even a shred of self-respect. Lucky for your friends, they've got you to ask their deepest, darkest questions for them. And lucky for you, we started this column to answer those most embarrassing inquiries.
The Scenario: Your friend is deathly afraid of cockroaches and worries that seeing one scurry across the floor means there are a few hundred colonizing the space in his walls and beneath his floors.
This fear is not uncommon. Cockroaches have been around for about 350 million years. In the relatively brief time they've coexisted with humans, we have loathed them, across cultures. Ancient Egyptians prayed to the ram-headed god Khnum to expel them, and Roman scholars and Jamestown settlers both wrote of their disgusting attributes. Cockroaches seem to inspire more phobia than do mosquitos, the malaria-spreading pests that are the world's actual deadliest animal.
Our disgust of roaches might be disproportionate to that of other pests, but is it, at any level, reasonable? Is your friend's visceral reaction triggered by the health hazard of these particular insects or the ick factors of their creepy-crawly movements, their invasion of human habitats; and their crunchy, alien-looking bodies? How sick can a person get from even a minor cockroach problem? Is finding one roach an indicator that your friend is already living in Joe's Apartment? And what's the likelihood that it was the filthiness of the place that drew the bugs to begin with?
The Reality: When people on the North American continent talk about cockroaches, they are probably talking about two of the 5,000 species that have been identified. The German cockroach (blattella germanica) and the Oriental cockroach (baatta orientalis) are the only varieties to regularly infest human habitats in the US. "The vast majority of the other species of roaches throughout the world are of no real health risk to humans," says Bill Hastings, director of specialty services for Indiana-based Rose Pest Solutions.
As far as guests go, cockroaches are not the best at remembering to wipe their feet and was their hands, so to speak. The insects gather bacteria and other disease sources and carry them on their bodies. The contents of their bellies are even more disgusting. "The gut of the cockroach is a very rich community of thousands of species of bacteria, and some of these can be pathogenic," says Coby Schal, an entomologist at North Carolina State University who has been studying roaches since the 1970s. However, only a large infestation or actually consuming cockroach bacteria—via food or utensils or plates the roach has touched—will make an otherwise healthy person ill with symptoms of food poisoning. (Worth noting: Roaches do tend to creep around kitchens because they feed on all things wet and moist.)
Seeing a single bug does mean there are likely more—a lot more. The cockroaches that pester US homes tend to hide in cracks and crevices near a food source and live in groups. "It is reasonable to multiply what you catch in a Roach Motel by 100 to estimate how many roaches you are sharing the home with," Schal says.
Oh, and if you'd like to further freak out your friend, ask when he saw the cockroach. They are generally nocturnal, so seeing one in the day might mean disruption of routine due to overpopulation.
Poor sanitation is not always the invite to a roach parade, however. The insects can hitch a ride in cardboard boxes or second-hand goods brought into the home or jump ship from a neighbor's home, Hastings says. "Even if the apartment is clean, if your neighbor has roaches, you will too," he adds. "They travel through the adjoining wall, usually where the water pipes are but also through the electrical and ventilation systems."
But poor sanitation, as demonstrated by food left out and stagnant water, encourages them to settle down and start a family beneath your floorboards. Schal says that "what keeps them coming is availability of food."
The Worst That Can Happen: If your friend has asthma, he might want to scurry. Cockroach droppings and molted exoskeletons can spur allergic reactions or asthma attacks, Hastings says, and these "can be very serious, even life-threatening" when there are large quantities of bug leftovers.
Schal points to a body of research linking allergens spread by cockroaches to chronic breathing problems. Back in 1997, the National Cooperative Inner-City Asthma Study found that 35 percent of urban children with asthma had particles related to roach infestation on their skin. Subsequent research has linked prevalence of roaches (and other pests) in a neighborhood to asthma rates, too.
What Is Probably Happening: While disgusting, a mid-sized cockroach infestation is rarely hazardous. "The health risks to humans from the German cockroach can be an issue if a person has a lung disease like asthma or they are highly allergic," says Hastings, "but generally speaking it takes a large infestation to be a health risk in most instances."
What to Tell Your Friend: Due to their evolutionary dexterity, cockroaches seem destined to outlive us. Creeping out humans is just what they're doing with their time until they become the post-apocalyptic inheritors of the Earth.
The sight of cockroaches does imply a health concern, but unless your friend has asthma or is so slovenly and unaware he might eat a roach or its droppings, that health risk is mild. Still, be sure to seal food and clean plates, utensils, and cooking tools before, during, or immediately after a roach episode.
Insecticides combat a cockroach infestation, but tell your friend not to, in paranoia, spray them around wildly like some germophobe Jackson Pollock. Schal notes that people who use home insecticides often absorb them and traces have been found in their urine. Hastings warns not to use a fogger. "The use of fogger-type pesticides only hide[s] the infestation," he says, "while they do kill some of the insects, the others are forced deeper into the walls or cabinets cracks and crevices … and once the fog has dissipated, there is no residual to kill the ones that come out of hiding."
While there is no way to prevent roaches from entering, there are steps to prevent them from staying. Your friend should channel the energy produced by his bug phobia into cleaning, moderate home repair and doing the dishes right after dinner.
"We say that the first three rules in pest control are sanitation, sanitation, sanitation," says Hastings. His anti-roach checklist includes filling cracks and crevices around cabinets and counters, using foam to seal areas around pipes, keeping food in airtight containers, not leaving dirty dishes in the open, vacuuming regularly, taking out the trash often and washing trash bins monthly. "By doing this you are removing the items cockroaches and other insects need to survive—food, water, and a place to lay their head," he says. "If you take away their food, or where they live, then they won't be there."