TECHNICALLY SPEAKING: Baits Aren’t Always The Answer

Despite the press I (and many other writers) have given baits, they are not the answer to every pest problem. In fact, the use of baits — perhaps more accurately the reduction in the use of sprays — has led to the resurgence of several pests, such as bedbugs, carpet beetles, silverfish and spiders.

The reason is simple: Up until about 10 years ago, the industry relied heavily on residual sprays and dusts as its primary strategy for killing cockroaches and ants. As the transition to baits occurred, non-targeted pests, such as carpet beetles and silverfish, which may be affected by baits, would rarely encounter the baits because of their limited distribution. Furthermore, pests such as spiders and bedbugs, which prey on other arthropods and blood respectively, are unaffected by baits.

Another result of bait use is that they have been so successful in reducing cockroach and ant populations that consumers see fewer of these pests and are beginning to see many other structural pests that went previously unnoticed. Thus, while baits have made significant inroads on two major industry pests, they are not always the best answer.

MAKING A DECISION. When technicians rely on pesticides to deal with "unbaitable" pests, considerable thought should be given to selecting an appropriate product for the job. Foremost in my mind are the customers and what they want. Because pesticides are potentially hazardous, and customers may have issues regarding pesticide use, technicians must be sensitive to their concerns.

We frequently encounter customers who have "special" requests. For example, they may have Oriental carpets and clothing damaged by carpet beetles and there is a baby in the house. They may have researched pesticide products on the Internet and made decisions about products they will not allow in their home.

Our challenge is to find pest management solutions to meet their needs, including the possible use of pesticides. This includes an in-depth discussion about pesticides, including their toxicity, potential hazards to children and pets, application techniques, residues, etc.

Since the organophosphates (chlorpyrifos and diazinon) and the carbamates (propoxur and bendiocarb) are disappearing from the marketplace, the type of active ingredient is becoming less of an issue. The industry is primarily left with pyrethroids, boric acid, silica gel, diatomaceous earth and a few other unique active ingredients (AI). However, there are some customers who are reluctant to have pyrethroids (and more rarely) boric acid applied in their home.

TARGETING THE PEST. Having cleared the hurdle of consumer concerns the next issue is the target pest. It is important to match the pest with an appropriate product. Factors that should be considered include resistance, repellency and efficacy. This type of information is not found on the product label and regardless if a pest is listed on a product label, it is not necessarily an indication of how effective the product is against that pest in the field. For the most part, this information is best determined through experience and reading trade journals and scientific articles to learn of others’ professional experiences.

The label poses significant questions in determining if a product is the right one for the job. Questions to answer during product selection include:

• Is the site of application (indoors/outdoors, food service/non-food service, school, hospital) included on the label?

• What application techniques (crack and crevice, spot, broadcast, aerosol) are permitted by the label?

• Is the target pest listed on the label? (not required by all states)

• What precautions are required when using the product (avoid breathing spray mist, avoid contacting treated surfaces, do not get on skin/hands/eyes, reentry times)?

• Is the product hazardous to non-target animals (pets, fish, birds)?

Another criteria I weigh heavily in product selection is the concentration of the applied product. Many of today’s pesticides are applied at rates around 0.05 percent or less. Applying products at such low concentrations significantly reduces the risk of accidental exposure and injury. Using products that recommend application rates around 0.5 percent is unnecessary.

Formulation is another important decision. It is critical in terms of the environment where it is applied, the target pest and longevity. Each formulation has pros and cons. The following summarizes this:

• Dusts consist of fine particles of dust, such as talc or clay that are coated with a thin layer of finely pulverized AI. Dusts are easy to use, last a long time and do not stain or injure plants. Dusts (except for one product containing deltamethrin) are ineffective when wet, do not stick to vertical surfaces, may leave a visible residue and can be displaced by air movement.

• Wettable powders are dry dust formulations designed for dispersal in water. They neither contain solvents that may have an odor nor do they cause skin irritation. Wettable powders have the same advantages as dusts, but often produce visible residues.

• Soluble powders are dry formulations that dissolve in water and form true solutions. They are easy to handle and do not produce visible residues.

• Flowables are liquid formulations composed of finely ground particles of the AI. They readily mix with water to form easily handled suspensions, which may leave a residue.

• Emulsifiable concentrates are easy to handle and rarely leave a residue. They tend to be more concentrated, thus, increasing the risk of exposure. Solvents may have an odor and/or affect products such as rubber and plastics, which soften when contacted.

• A microencapsulated formulation consists of a liquid or dry AI surrounded by a plastic coating, which gradually breakdown, slowly releasing the AI. Microencapsulation allows the AI to remain for a longer period of time than emulsifiable concentrates, maintains the concentration at low levels and protects it from environmental effects.

• Aerosols are usually ready-to-use products that contain a solvent and a propellant. They dispense fine pesticide particles into the air for a short period of time. The AI concentration typically is low. Toxic effects are increased through the addition of synergists.

CONCLUSION. Baits have mesmerized the industry but they are not the only answer. The selection of a pesticide should be based on an informed decision.The author is technical director of American Pest Management, Takoma Park, Md. He can be reached at rkramer@pctonline.com.