[Public Health] Closing in on Bed Bugs

"Don’t let the bed bugs bite." I can remember as a child this ritualistic prayer we said every night before we went to bed. After more than 50 years, once again I imagine this prayer is being heard in most major metropolitan areas around the world.

Bed bugs are not a new problem — one of the oldest pest control companies, known as "Bug Destroyers to Her Majesty and the Royal Family," can be traced to 1695 when one of its founders developed a pest control powder to deal with the No. 1 pest of the day, bed bugs. Occasionally, the "pest management professional" of the day had to travel hundreds of miles to catch a handful of bugs feasting on royal blood.

Besides cockroaches, lice, rats and mice, one of the major stowaways on the earliest ships arriving in the "New World" were bed bugs. The bed bug was probably the first introduced pest to achieve pestiferous status because it survived quite well in the earlier agrarian society, whereas, pest status for other introduced pests was more dependent on urbanization, which did not occur until the mid-1800s (Snetsinger, 1983).

A historical perspective on bed bugs will provide a better understanding of why they have suddenly become a major problem and insight on what control strategies will prove the most effective. As previously indicated, bed bugs have been associated with humans since the beginning of modern civilization and urbanization. As people congregated in cities, the potential for moving bed bugs dramatically increased. With more people living closer together, there was a greater opportunity for the bugs to find their preferred human hosts and flourish.

BED BUG HISTORY. The pest control industry in its infancy had very few tools with which to work. Some of the treatment protocols for bed bugs contained in the U.S. Department of Agriculture Leaflet No. 146 Bed bugs (Back, 1937) included the following:

• Fumigation. "There is no better way to stamp out infestation than by fumigation. A fumigation of more than 12 hours or more is more desirable…Of the fumigants now commercially available hydrocyanic gas is particularly effective when used in detached vacated buildings. Individual apartments could be treated professionally using combinations of carbon dioxide and ethylene oxide, methyl formate or methyl bromide. Sulfur dioxide could also be used by burning two pounds of sulfur per 1,000 cubic feet." While highly effective, use of these materials had their inherent drawbacks, e.g., cyanide is highly toxic to humans and killed people and sulfur dioxide was very odiferous.

• Superheating. "Superheating rooms and even entire buildings to a temperature of 120oF to 125oF for several hours will completely eliminate bedbug infestations. Superheating has been resorted to repeatedly with success during hot summer weather...It is good to place thermometers in various parts of the room or rooms in order to note the temperature obtained. The temperature in the cracks where the bugs are secreted must be held as high as 120oF." Sound familiar? Consider Dr. Walter Ebeling’s work on heat treatment of drywood termites and recent work on heat fumigation for the control of German cockroaches in commercial food-service facilities.

• Use of sprays. "Ordinary fly sprays consisting largely of high-grade, water-white kerosene, practically stainless, with small additions of pyrethrum extract, are dependable for the destruction of bed bugs and their eggs. They must, however, be brought into contact with the bugs...Vaporizing machines that fill the room with a mist or fog of insecticide are not ordinarily dependable for quickly stamping out bedbug infestations."

• Hand application of liquids. "When no equipment for applying sprays is at hand, much good can be accomplished by using a large feather or small brush to apply kerosene, turpentine, benzene or gasoline to cracks of bedsteads and other hiding places of the bugs. When using these liquids, keep the windows open and fire away during the period of application, otherwise fire or explosions may occur." This would also deter most people from smoking in bed.

• Treating infestation in upholstered furniture. "When such services (fumigation) are not available, the furniture should be placed on an open porch or in a shed and the parts affected treated with liberal applications of clear gasoline."

The Dominion of Canada Division of Entomology Processed Publication No: 33, The Bedbug and Its Control (Twinn, 1945) furthered the science of bedbug control with the following recommendations:

• Spraying. "The spray should be applied thoroughly to bedsteads, springs and mattresses, other articles of furniture and the walls, paying particular attention to cracks and crevices in which the bugs hide. At the time of this writing most of the fly and bed bug sprays on the market consist of the synthetic insecticides known as thiocyanates in refined kerosene. The new synthetic insecticide, DDT, is very effective in destroying bed bugs." No! I don’t think the current bed bug situation will bring DDT back.

• Powders. "Insecticides in powder form are generally considered less satisfactory than sprays in controlling bed bugs, but may be effective when thoroughly applied. Derris and pyrethrum and processed powders containing DDT are satisfactory insecticides for the purpose…"

• Home remedies have also played a role in controlling bed bugs, e.g., The Handbook of Practical Receipts (Branston, 1857) suggests that bed bugs be controlled with a mixture of soft soap and snuff or arsenic (Snetsinger, 1983). The USDA leaflet further points out that individual efforts may exacerbate the problem, i.e., "Upon becoming more numerous or after the housewife has been fighting them in a haphazard manner, the bugs usually become more scattered…"

The control of bed bugs took a radical turn for the better with the advent of modern pesticides following WWII. DDT, chlordane, lindane and a host of other new products proved to be very effective in controlling bed bugs. Most of the post-WWII insecticide classes (chlorinated hydrocarbons organophosphates and carbamates) of products have been eliminated from our arsenal, leaving us with predominately pyrethroids and non-organic products.

The advent of modern pesticides caused bed bugs to virtually disappear to the point that they were rarely encountered. During my own experiences as an entomologist since 1968, I never encountered a single bed bug problem — this included 22 years in the military and almost four years outside the United States. The only bed bugs I encountered in the mid-1970s were colonized at the USDA Insects Affecting Man and Animals Laboratory in Gainesville, Fla. At that time, because bed bugs were such a minimal problem, the colonies were being disposed of because there was no longer any interest in bed bug research. For more than 30 years there has been a dearth of research articles published on bed bugs, reflecting their significantly diminished pest status.

TODAY’S PROBLEMS. So why are bed bugs suddenly an emerging pest problem? There are many possible explanations for the meteoric rise in bed bug infestations in large metropolitan areas:

• Pest management practices have changed significantly during the past 10 years. Baseboards (a favored bug hiding place) are no longer routinely sprayed with liquid pesticides.

• Baits are the product of choice for treating ants, cockroaches and most other crawling insects — baits have no effect on bed bugs because they only feed on blood.

• The classes of insecticides (chlorinated hydrocarbons, cyclodienes organophosphates, carbamates) that traditionally were successful in eradicating bed bugs are no longer available. Most of the products registered for indoor use are either inorganics or pyrethroids, which have not been adequately evaluated against bed bugs.

• Travel remains one of the main sources of bed bug introductions. Despite the effects of Sept. 11, there is a lot of national and international travel and bed bugs are being found more frequently in hotels and motels where they can be picked up and readily transported home.

• Inner-city living is crowded with sometimes four to six people living in an efficiency apartment. If bed bugs are introduced into this situation, they are spread to other apartments when the tenants split up.

• Rental furniture, transport vehicles and rental trucks are a potential source of introduction. In large cities, apartment tenants frequently rent furniture that can become infested, transported in a vehicle, stored in a warehouse and then rented to another unsuspecting customer. The bugs’ ability to live several months without feeding facilitates this method of dispersal.

• We have observed a tenant carry an infested mattress out of one building and place it on the street for disposal, only to have the mattress picked up by someone in another building and taken inside.

• Child and adult caretakers are another potential source of introduction when they live in or visit an infested residence.

Dealing with these infestations has turned out to be a matter of trial and error. Most manufacturers that list bed bugs on their labels have done so as a matter of course, not because they have conducted studies to determine how their products affect bed bugs. Answers the manufacturers need to provide us are how effective their products are in killing the bugs, whether there is any repellency and/or resistance.

Potentially, resistance is a significant concern. Historically, one of the major reasons the USDA maintained bed bug colonies was to study resistance in bed bugs. This topic was also of great interest to the World Health Organization (WHO). One of the most common research topics regarding bed bugs 30+ years ago was resistance.

The resistance patterns observed in bed bugs years ago was like that observed in German cockroaches, e.g., widespread, involving several products and cross resistance. In many respects, the biology and habits of bed bugs are similar to cockroaches except that they have the ability to endure extended periods of starvation. The biotic potential of bed bugs certainly rivals German cockroaches, i.e., the female lays 200 to 500 eggs, developmental time (egg to adult) can be as short as 21 days and the adults can live for up to one year. Thus, populations can explode.

SUCCESSFUL TREATMENTS. What can we learn from history and what do you need to know to successfully treat for bed bugs:

• Bed bugs hide in cracks and crevices during the day. They hide in the seams of mattresses, box springs, bed slats, cracks on bed frames, hollow bed legs, as well as wood and paper surfaces.

• Over time, the harborage areas become filled with the molted skins, feces and old egg shells of the resident bed bugs. These areas have a characteristic smell caused by a secretion that they emit.

• At night they leave their daytime resting sites to feed on their hosts, which include humans, birds and family pets.

• The blood meal requires three to 10 minutes and usually goes unnoticed by the victim. After feeding, the bite site may become inflamed and itch severely in sensitive people.

• Typically, bed bugs feed every three days. Larger ones can survive two months without feeding.

• Our experience has shown that many, if not all, of the pyrethroids will cause the bugs to disperse if they are not killed by direct contact, exacerbating the problem, particularly in multi-family buildings.

• Historically, dusts, e.g., boric acid and others, have not proven effective against bed bugs, namely because there is no way for the chemical to be ingested or absorbed.

PRACTICAL TIPS. The following are tips on how our company has treated for bed bugs:

• A thorough inspection is necessary to detect harborage sites. The odor and specks (little spots of excreted blood they produce) assist in pinpointing these areas.

• In multi-unit family housing all adjoining housing units should be inspected.

• Mattresses should be encased in plastic mattress bags.

• Bedding should be washed weekly.

• A vacuum can be used to physically remove some of the bugs.

• Thorough applications of non-repellent residual insecticides (e.g., propoxur) should be applied to cracks and crevices, behind baseboards and into other known or suspected harborage areas. We have tried chlorphenapyr and it appeared to work well but was slower acting.

Products containing acephate also are available, but concerns over odor have deterred our use of these products.

• Furniture, especially mattresses, box springs and all bed frame components, should be lightly sprayed with a registered repellent pesticide (e.g., permethrin). We have had less success with products containing pyrethrin.

CONCLUSION. Regarding bed bugs there is no doubt that history is repeating itself, i.e., they are back with a vengeance and current experience dictates treatments resorting to the old days of baseboard spraying. Hopefully, you’ll be the one to answer your customer’s prayer, "Please don’t let the bed bugs bite."

The author is technical director of American Pest Management, Takoma Park, Md.