[Technically Speaking] Part II: Oh, So Many Choices

Okay, so you followed my advice in last month’s column (Find Them First, Part I, PCT, July 2005) — you looked up, down, all around, inside and outside. You identified the pests causing the problem, their habitats, conducive conditions and you even found where they are getting in. Now it’s time to solve the customer’s problem. First and foremost, remember there is no prescriptive way to address a pest problem; every situation is different and typically requires you to tweak your approach and sometimes become extremely creative.

Habitat modification does several things to facilitate control of pests:

• It stresses the population by removing the resources it depends on for survival, e.g., food, moisture and harborage.

• It can cause the population to relocate.

• It can cause the population to forage in different locations.

• It stresses the population, making them more susceptible to pesticides.

Exclusion is one of the most effective ways of keeping pests out of structures. After all, this is all most customers want — out of sight, out of mind. Like pesticides, there is a multitude of sealing materials at our disposal and the key is selecting the right product for the job. Some of the products commonly used in our industry include:

• Caulk — Caulks are best designed for keeping out insects and moisture. It is important to understand the various properties of caulking materials, e.g., solubility (silicone, oil or water based), paintability, compatibility with different surface materials and durability.

• Foam — Foam is designed to fill larger voids to exclude insects and rodents; however, in the case of rodents, other materials should be incorporated, such as copper or steel wool, wire, etc. Foam can be a disaster if misused and it can create some ugly messes. Factors to consider when using foam are expandability, appearance, durability and paintability.

• Other products include sheet metal, wire mesh, door sweeps (I prefer brushes) and other products suitable for keeping pests out of structures.

Mechanical control is most effective when dealing with vertebrate pests. It offers little control of insect pests other than to harvest adults. With insect pests, it is more important to find the source of the problem and address it from that perspective. In some cases, mechanical devices such as fly and mosquito traps can draw more insects into the area than they actually capture and should be placed carefully to avoid this situation.

TIMES ARE CHANGING. Back in the good ol’ days we had products like DDT and chlordane, and not too long ago we had malathion, diazinon and chlorpyrifos. As much as many people believed they were the best, we have even better products today that are applied at much lower concentrations and rates of application.

To use today’s products effectively, we must understand how they work and how pests respond to them. Unfortunately, we cannot rely on the product label for this information because some manufacturers put every conceivable pest on their label with little regard to proven efficacy through independent research. This is not necessarily a criticism of this practice because I believe most pests will die if they are brought into contact with sufficient AI in the currently registered products. There are many factors that play a role in how fast and how effective a product is against a specific pest; unfortunately, we are often left to discover for ourselves what the best product is for the job.

I can’t tell you how many times I have been asked what the best product is for a specific pest. The simple truthful answer is "the one that works." There has been a proliferation of products over the past few years, something that some of us never expected given the expense of testing and registration.

Perhaps it is time to consider classifying pesticides into three groups (repellents, non-repellents and baits) because to do otherwise is extremely difficult since the active ingredients are new and cannot be generally classified and have different modes of action than historical pesticides. The following is a brief discussion of how these broad classes of products could be used.

Repellents (many of the pyrethroids) are effective toxicants, but in many cases, they require direct contact with the insect to kill it, or they need to be in a slow release formulation that reduces repellency and allows the insects to contact a sufficient quantity to kill them. These products are very effective around foundations, wall penetrations and other areas where we want to minimize entry into the structure. For the most part, they begin repelling insects immediately upon application and results are typically seen in a short period of time.

Non-repellents do not stop pests from entering the structure; however, their benefit is that they kill pests over several days, depending on the concentration of the product. Their down side is that pest activity may remain high until the full effect of the application is realized. Sometimes the use of repellent products at the points of entry in combination with the longer-term killing effect of the non-repellent products is useful. It solves the customer’s immediate problem of pests entering the structure and provides long-term control sought by the firm.

It is my opinion that any bait that is ingested in sufficient quantity kills virtually any pest we encounter. Therein lies the problem — ingesting the bait. There has been a proliferation of baits over the past five to 10 years and we are stuck sorting through the quagmire. We have baits for cockroaches, termites, ants, mice, rats and virtually every pest we encounter except perhaps the blood feeders. These baits have a multitude of concentrations, active ingredients and attractants.

IT’S UP TO YOU. Unfortunately, the only way to determine what the best bait is for a given situation is to do some experimentation, i.e., put out several products and see which ones are taken. Another factor is the concentration of the bait, e.g., too strong and the foragers are dead before they leave the feeding trough; and too weak and the infestation goes on forever.

It’s great to have so many choices, but we have to think and make wise decisions on what products to use and how to use them. Most importantly read the product label prior to using any product.

The author is president of Innovative Pest Management, Brookeville, Md. He can be reached at 301/ 570-3900 or via e-mail at rkramer@giemedia.com.