Bed bugs making a comeback

“Nitey-nite, sleep tight. Don’t let the bed bugs bite!”

… And that was supposed to make a little kid feel all cozy and safe as Mom closed the bedroom door on you? Wait, what are we talking about here? Insects with teeth?

To a child of the ’50s and ’60s — or even the ’70s, ’80s or ’90s — bed bugs were fairy tale creatures from long ago and far away, and Mom’s curious good night ritual just one of the incomprehensible things parents sometimes said like, “Don’t tell your grandmother how to milk a duck.”

But anyone who has lived through a bed bug infestation will tell you they’re not only real, but that saying “don’t let the bed bugs bite” is one thing and making it happen quite another.

Up through the mid-1940s, bed bugs were a common and much-despised problem throughout the country. But in 1939, Swiss Chemist Paul Müeller discovered that dichlorodiphenyltrichloroethane, a compound first synthesized in the 1870s, had potent insecticidal properties. By the second half of World War II, DDT was being used to protect soldiers and civilians from insect-borne diseases such as malaria and typhus and, in 1945, it became available in America for general use.

So effective was the pesticide that within a decade, bedbugs had been virtually exterminated from most regions of the country and for the next 50 years, the insect was largely relegated to the realm of myth.

But myth they most certainly are not. The common bed bug, Cimex lectularius, often is described as about the size and shape of an apple seed, but that seems to me a good deal too large. At about 5 mm long x 2 mm wide x 1 mm thick (before feeding), I think of them as just a tad beefier than a sesame seed, if sesame seeds were a dark reddish brown.

Actually, it’s only the adult stage that’s dark in color. The five nymph (larval) stages that precede it are much lighter. Nymphs need to have a blood meal in order to advance to the next stage, the whole life cycle from egg to adult taking about five weeks. Adults feed every 3-7 days and under good conditions (for them) live the better part of a year.

Though flightless, they can scurry quickly across the floor and up vertical surfaces in search of a human host (and yes, it’s only our blood they want). After a random scramble, they zero in on us through their sensitivity to heat and the carbon dioxide we exhale.

Bed bugs are most active between midnight and 5 a.m., when people generally experience their deepest sleep. Once finding a host, they typically probe into the skin several times before feeding, resulting in a characteristic line of 3-4 welts raised in those sensitive to their bite. (About 20 percent of us don’t react to the bite.) Anesthetics in its saliva mean the bite is painless and anticoagulants ensure that the blood flows freely for the 5-10 minutes it takes to drink its fill.

After feeding, the parasites retreat to safe havens in mattress seams, box springs, grooves between floor tiles, beneath baseboards and the like, where they will remain until hunger drives them out to forage again.

In the mid-1990s, a few reports started coming in to the Centers for Disease Control of bed bug infestations popping up in New York City and a few other, primarily urban areas. Since then, C. lectularius has re-established its position across the country as one of the main reasons to call an exterminator. One of the causes for this resurgence is increased international travel to parts of the world they remained abundant; bed bugs love suitcases.

Others reasons include their evolution of a level of resistance to the pesticides used to control them and people’s simple lack of awareness of bed bugs’ existence, which plays into their willingness to adopt discarded furniture.

The good news, if there’s any to be had, is that there is no record of bed bugs ever having transmitted disease to their human hosts.

And there’s this: Researchers at Penn State recently developed a product for sale (only) to licensed exterminators called Aprehend whose active ingredient is Beauveria bassiana, a natural fungal disease of insects. A mixture of fungal spores (harmless to humans and pets) is applied to surfaces where bed bugs travel, such as on the floor around beds.

The tiny spores attach to an insect’s feet, killing it within a week of contact. An application is said to remain active for three months.

Ken Baker is a scientist and a retired biology professor. If you have a natural history topic you’d like the author to consider for an upcoming column, email your idea to rweaver@advertiser-tribune.com.