Bed Bugs: The Science and Costs of Infestation
Our relationship with bed bugs is intimate. They share our beds, they feed on our blood at night, and they disappear by dawn, often leaving nothing more than a raised welt on our skin, a token of last night’s encounter.
Therein lies the problem—their cryptic nature makes detection and control very difficult.
Bed bugs don’t fly or jump. We are solely responsible for their spread.
Bed bugs are flat, so they can hide in cracks and crevices—their harborages—where you sleep. They have grappling hooks at the end of their feet, enabling them to navigate the geography of your bed and body.
Small, flat, flightless bugs? So why is it so hard to prevent and control them?
There is more to solving the problem than you would expect. There is a disparity between the extremely negative and almost phobic public perception of bed bugs and the industry’s response. Why don’t we have better control strategies?
First, let’s look at efforts to control bed bugs through insecticides. Studies from the University of Kentucky have found widespread resistance to pyrethroids, a commonly used insecticide class, in bed bugs across the United States. That means we need new chemistries and modes of action to avoid problems with resistance. But it’s easier to tweak existing chemical architecture than to design novel chemistries.
That’s why we don’t see new insecticides: the investment is too great, the risk too high, and the time-to-market too long.
Insecticide toxicity is another concern. The Centers for Disease Control and Prevention (CDC) documented 111 cases of bed bug-related insecticide misuse from 2003 to 2010. These illnesses were the result of excessive insecticide application. In one fatal case, the husband of a woman suffering from hypertension and depression applied a lawn-and-garden insect killer to their mattress and box springs, followed by nine cans of an insecticide fogger in the same day. Two days later, they reapplied insecticide to the bedroom and nine MORE cans in the house. On that day, the woman also applied insecticide to her arms, chest, and hair. She died 11 days later.
Heat treatment is another, less toxic option for controlling bed bugs. Heat treatment is basically “cooking” a room or furniture with steam or air heated to 120oF to 140oF for up to 4 hours. While heat treatment is effective at killing bed bugs in a room, it might also force bed bugs to migrate into adjacent rooms. Heat treatment can be expensive —up to $1,000 per treatment—and has no residual activity (that means it kills whatever is there at the moment but will not prevent a re-infestation.) Heat treatment can also melt candles, warp CDs, and kill your houseplants.
A third control option is a very fine, silica-rich dust that’s used as an abrasive in toothpaste, an absorbent in cat litter, and a binding agent in dynamite. Diatomaceous earth, or DE, as it’s also called, is an effective insecticide for bed bugs and other domestic pests. The silica absorbs and abrades the wax layer on an insect’s exoskeleton, and the insect dies of dehydration. However, DE leaves obvious white dust, advertising that you have a pest problem, and it could take weeks to kill an infestation.
Even with these three different control strategies (toxic chemicals, heat, or silica dust), infestation rates are rising.
Why is this the case?
Pesticides used to treat infestations of pests that carry diseases harmful to humans only account for less than 2% of global pesticide sales. And bed bugs aren’t vectors!
Because bed bugs make up such a small share of the overall market for pesticides, and they don’t qualify for vector biology funding by the NIH, there’s not much financial incentive to control them.
Until earlier this year, the Department of Housing and Urban Development (HUD) provided funding for housing authorities to control bed bugs. That program has been eliminated, and local housing authorities need to creatively budget for bed bug control within existing funds.
But bed bugs incur hidden costs. Most cities prohibit the disposal of infested furniture in those regular green dumpsters we’re familiar with. Furniture can only be discarded in a special municipal or construction dumpster, which costs thousands more to purchase, register, and maintain. If an apartment complex can’t afford a construction dumpster, then tenants may discard the infested furniture on the street where—no surprise—someone else will pick it up and start a new infestation.
Remember, bed bugs don’t fly or jump. We are their vectors.
Problems and misconceptions with pesticides, expensive treatments, and funding bottlenecks at the federal level reveal that there’s more to the bed bug problem than meets the eye — or the mattress.
Finally, our understanding of bed bug biology is about 50 years behind our understanding of mosquito biology, so we really need to catch up. At SRI, researchers are working on improving infestation detection. Once we detect them, we still need sustainable control strategies that are targeted, effective, and nontoxic to other organisms. We have a long way to go, and like so many other aspects of this insect, details remain cryptic.