Periodic Service for Fabric Pests

Last month, I reported that many PCOs are enjoying a moderate increase in carpet beetle/clothes moth service calls, and I explained why. This article will suggest some new strategies and old/new materials that are available to better service clients.

Forty years ago, PCOs had a variety of choices to mothproof susceptible fabrics. Dr. Lee Truman, an industry veteran from Indiana, treated thousands of articles with arsenicals, fluorides and even with DDT. These chemicals protected fabrics exposed or in storage, for many years. Arnold Mallis in his 4^th Edition of The Handbook of Pest Control preferred to call them "fabric pest deterrents" rather than "mothproofers."

DDT was widely believed to be a good mothproofer because it was thought to be deadly to carpet beetles - another "Myth Conception!" The beetles walked on treated fabric without injury. DDT did not even repel the insects, much less kill the eggs. A two-hour exposure on DDT-treated wool had only a slight effect on the more susceptible webbing clothes moth, according to Mallis. Roy Bry, a recently retired USDA researcher, also reported that DDT was essentially a feeding retardant for fabric pests. Because there are no "permanent" mothproofers (DDT, silicafluorides, etc.) available to pest control professionals at the present time, PCOs who service homes and institutions quarterly, semi-annually or annually could add treatment of rugs and other materials susceptible to fabric pest attack to their service.

LIKELY HARBORAGE SITES. Few products permit overall treatment of woolen or wool-rich rugs or garments, but it really is unnecessary to treat an entire rug. The insects do not infest those parts exposed to light or where traffic is common. Industry consultant Dr. Tom Parker stresses a spot often overlooked: the compressed fibers directly under furniture legs. Often these spots are totally eaten away, found only when the furniture is moved. Spot treatment under and behind low furniture is critical, as is treatment of the edges of wall-to-wall carpeting. Dr. Lee Truman told me that carpet edges under the quarter round are often totally eaten. Few places still have such molding, but a spray directed behind and under the baseboard rim is essential. Truman warns that treating the edge only could give the border area a slight cast, and he suggests feathering out the spray away from the wall. In some cases, an aerosol crack and crevice treatment directed at this area is more likely to gain control because of better distribution produced by the propellant in a pressurized aerosol container.

Pianos and other bulky furniture items should be moved to reach the rug. If it is not feasible to move massive pieces of furniture, perhaps directing the tip from a 15# pressurized aerosol container into the crevice at the leg’s base will permeate the compacted carpet. I believe the still-wet propellant and solvent will penetrate the critical area below the base of the rug. One characteristic of materials such as chlorpyrifos and pyrethroids that adsorb onto organics is that they will penetrate to the bottom of the fiber. Felts in pianos also may be targets of fabric pest. Little used, old-style upholstered furniture is a favorite target because of the filling typically used in older cushions. Beetles often reach baseboard areas from attic infestations. Fireplace areas are the target site for beetles coming from a dead animal on a shelf in the flue of an unused hearth.

PCOs may encounter a problem with deep pile rugs. Directions on pesticide labels for carpet beetle control generally reflect the manufacturer’s warning that excessive spraying could cause damage. It is not likely that the bottom of the loop under the rug will get wet by following the label directions. A carpet beetle larva often snips a bite out of the base of the loop below, and the tuft falls out. Parker recommends that the edge of oriental rugs be turned back for treatment. Perhaps the PCO who owns an industrial vacuum sweeper cold use it on some of the critical spots, exposing the carpet base so it can be reached more easily by the spray particles.

OTHER OPTIONS. Another approach would be to use a pressurized aerosol container of synergized pyrethrins which are labeled for carpet beetle and moth control. Most people think pyrethrum degrades rapidly. It does… in lighted areas. It is a "Myth Conception" to believe that pyrethrum degrades everywhere it is sprayed. But in a dark place, where carpet beetle larvae and moths feed, it has an extended residual life. Roy Bry claims wool treated more than 27 months earlier with synergized pyrethrins was not attacked by carpet beetles in a darkened room. Here’s another "Myth Conception": the storage area must be pitch black at all times. Bry says low intensity light on occasion does not materially degrade the pyrethrum.

Yet another "Myth Conception" was shattered by Bry when he said his experiments with the synergist piperonyl butoxide (PB) proved that there was no difference in effectiveness between ratios of one part pyrethrin to five or 10 parts PB.

Bry found that permethrin, applied with pressurized aerosol container, protected wool against black carpet beetle and furniture carpet beetle attack after aging in a darkened area for 128 months - more than 10 years! In another test, Bry achieved more than six years of protection against black carpet beetles, furniture carpet beetles and webbing clothes moths with a pressurized aerosol container holding a combination of tetramethrin and Sumethrin.

Another surprise: Who would consider comparing the "short-lived" pyrethrum with a chlorinated hydrocarbon? A study in Finland in 1971 found that synergized pyrethrins lasted as long as lindane did in protecting wool in darkened storage.

After getting these reports about extended residual values of pyrethrins and pyrethroids on fabric in darkened storage, I must consider the expression "temporary mothproofer" a "Myth Conception" in the published literature. The expression should refer to exposed situations only.

Most of the organophosphates and pyrehroids now labeled for carpet beetle and moth control are adsorbed onto the fibers so effectively that they may not be available to insects for a fast kill. But what does that matter if they are effective in preventing the larva from eating the fabric?

OLD-TIME REMEDIES. Old-time remedies for fabric pest control are paradichlorobenzene (PDB) and napthalene. Generations of Americans have grown up in homes that reeked with the odor of these weak fumigants. In retrospect, they have provided much more peace of mind than relief from damage to wool or wool-rich fabrics.

Control is possible with these weak fumigants only with high concentrations in air-tight containers or storage rooms. But universal underclosing by most consumers does not repel or kill these pests. I’ll be writing about the value of PDB and napthalene as an animal repellent in a future "Myth Conceptions" column. According to medical reports I have seen, there are a few people who have suffered medical problems from breathing heavy concentrations or fumes of PDB and napthalene for extended periods.

In today’s litigious climate, the possibility of someone suffering an adverse reaction to these weak fumigants may rule out their use by PCOs. The public, however, will probably continue to buy and use these traditional "remedies."

WHAT ABOUT DDVP? Many PCOs believe that the EPA has buried DDVP in the cemetery of useful remedies. This too is a "Myth Conception." DDVP is alive and well! What used to be called the "No Pest Strip" is now the "Pest Strip" and is currently available to the pest control industry. According to Dr. Tom Parker, DDVP is very effective at incredibly low levels in closed spaces against fabric pests. Twenty parts per trillion (ppt) of DDVP in the air is toxic to larvae and emerging adult carpet beetles (15 ppt or clothes moths). He suggests hanging the strip high because Vapona vapor is heavier than air and does not stratify the way PDB and napthalene do. Parker says the "Pest Strips" would work well in attics and should be changed in early spring and in the summer.

Scientists in the United States, Soviet Union and Japan are working hard to develop other alternatives to controlling fabric pests. Until they develop long-term mothproofers that are light stable and available for PCOs to use, PCOs should contract with their clients to treat premises for fabric pest control at least once or twice a year.

Harry Katz is a columnist for PCT.