Bust Pests With Dust

One of the industry’s longest running control tools, dusts have been part of the pest control’s professional’s arsenal for decades.

While they can be tricky to apply — with the biggest problem being overapplication — this formulation offers many unique advantages. For one, dusts offer broad spectrum control of a wide array of pests, including cockroaches, ants, spiders, bees and wasps, bed bugs, occasional invaders and stored product pests. Dusts are particularly effective at killing crawling insect pests, since they are easily picked up by insects that creep over treated surfaces. (use photo on page 1125 of Mallis?) And when applied into wall voids, dusts penetrate into less accessible harborages where pests often reside.

Dusts also figure prominently in the “once-a-year” pest control treatments provided by many professionals. In these types of treatments, dusts are applied in attics, wall voids and other out-of-the-way locations where their residual activity can last up to one year if left undisturbed.

HOW THEY WORK. Most dusts come in formulations that contain 100-percent active ingredient or are made by combining an active ingredient with an inert dust diluent to facilitate application and dispersal of the toxicant.

Particle shape and size play an important role in both the ease of application and effectiveness of dusts. Round or crystalline particles flow more freely during application, but do not adhere to vertical surfaces as well as flat, fibrous or irregular particles. Particle size is an important factor because the insecticidal activity of dusts generally increases as particle size decreases.

The active ingredients in dust formulations feature both inorganic minerals and natural or synthetic organic insecticides. Most of the inorganic dust materials are mined from earthen deposits before being refined and formulated for use as insecticides (i.e. diatomaceous earth).

Inorganic insecticides, such as boric acid and silica gel, provide long-term control but are slower-acting than synthetic organic insecticides. Boric acid interferes with cellular energy conversion after it is inadvertently eaten by the insect as it grooms its body. Meanwhile, silica gels and diatomaceous earth disrupt cuticle integrity by absorbing or abrading the protective wax coating of the insect cuticle, making the insect susceptible to desiccation.

Dusts that feature organic insecticides (typically pyrethroids), act more quickly than dusts containing inorganic materials. The active ingredients in these dusts are generally nerve poisons, and they must penetrate the insect cuticle and then be transferred to the nervous system where they exert their toxic effect. Certain dusts, such as Drione,® combine an inorganic dust base (amorphous silica gel) with an organic insecticide (natural pyrethrins).

A variety of application equipment is available for effective application of dusts. Small handheld dusters are convenient and easy to transport. Larger applicators hold a higher volume of dust, and power dusters are another option. Today’s sophisticated dusters also utilize crack and crevice attachments for dispersing dust in harborages.
 
PROS & CONS. Dusts offer a number of advantages to pest control professionals, although they do have some limitations. They are ready-to-use, low in odor, require simple equipment to apply, and offer long-term residual control when applied in protected environments. Because they cling to vertical surfaces, they’re particularly effective in wall voids. In addition, most dusts are nonflammable and nonstaining.

However, on exposed surfaces, dusts are unsightly, and if excess amounts are applied, the deposit may be repellent to insects. Care should be taken when filling dusting equipment and when applying dusts in enclosed areas. Most dust formulations are not effective when they become wet. However in 1995, a waterproof dust (DeltaDust®) was introduced.

On the down side, dusts are messy, they can drift easily and contaminate nontarget surfaces, and they can irritate the eyes, nose, throat and skin. In addition, unless they are properly trained, technicians often have difficulty achieving an even distribution of dust on surfaces, resulting in potential misapplications.
 
THE FUTURE. For more than 75 years, dusts have been an important tool in the pest control industry’s arsenal. Why? Quite simply, they work. And if recent advancements in formulations technology, technical education and equipment are any indication, it’s a good bet dusts are going to be around for another 75 years.

Dusts: Part of Pest Control History
Throughout the industry’s history, dust use has fluctuated with the times. Widely used by professionals prior to World War II, dusts fell into disfavor with the development of modern liquid insecticides in the 1940s. Their popularity decreased further with the dawn of the environmental movement in the early 1960s.

But dusts experienced a rebirth in 1979 with the introduction of Ficam® by Nor-Am Chemical Co. Although the product was withdrawn in 2002, it played an important role in re-establishing this formulation, since an important component of its launch was the manufacturer’s commitment to education on proper application of the product.

The resurgence continued as application equipment improved and the industry began promoting the concept of IPM. And the introduction of Tempo® Dust in 1994 and DeltaDust,TM the first water-proof dust formulation, in 1995, spurred further interest in this product category, making dusts an increasingly viable control option for a variety of accounts.

Dusting Tips and Recommendations

Effective dusting takes practice and experience to develop a “feel” for applying the correct amount of material when using handheld equipment. The applicator tip is often inserted into a crack or void so you can’t see exactly how much dust is dispensed. Here are some application tips, excerpted from Bayer Environmental Science’s new Dust Solution Guide, that will help you to apply dust more effectively.

 
• Examine the applicator and pay special attention to the placement of the pickup tube inside the applicator.
• Corn starch is a great material for demonstrating and practicing dust applications.
• Fill handheld dusters that are squeezed approximately half full, leaving room to more easily compress the applicator.
• The angle of the duster and the strength exerted when making an application will affect the amount of dust that is dispensed.
• Practice in an open area outside with the applicator positioned at different angles so you can see how much dust comes out.
• Listen carefully; most applicators make a distinctive sound when too much dust rushes out of the applicator tip.
• Shaking the applicator immediately prior to treatment will help create a cloud of dust in the airspace of the applicator and help facilitate a light uniform application. Inserting a marble inside the applicator can help break up any clumps of dust that are present.
• Apply a thin layer of dust into crevices, cracks and voids. This is usually accomplished when the pickup tube is in the air space, not buried in dust. The idea is to “float” a small amount of dust into the void or onto the surface.
• Avoid applying too much dust. It’s not economical or necessary for control. Thick layers or clumps of dust may repel some pests.
• Adding an extension tip or hose to dust equipment may allow for easier treatment of hard-to-reach areas.
• The Dustick® provides an extension up to 20 feet for treating hard-to-reach bee and wasp nests.
• Dusts can be used in combination with other formulations such as bait gels, stations, granules, and liquid sprays. Do not apply dust directly on top of bait placements.
• A long-handled, narrow scoop or spoon and a funnel are helpful when filling dust applicators.
• Store dusts in their original containers, keeping them sealed, as many dust formulations readily absorb moisture, which will make them more difficult to apply.
• Zip-top plastic bags are good for storing small handheld dusting equipment when not in use.

The Dust Solution Guide is the fifth solution guide now offered in Bayer’s Solution Guide series. To get your free Bayer Dust Solution Guide, call Bayer customer service at 1-800-331-2867, ask your Bayer Field Sales Representative or visit www.BackedbyBayer.com.