[Technically Speaking] Attack the perimeter!

In my opinion, unless you live in the Deep South where there is only one real season, summer, spring is the most spectacular season of the year. It is the time when the sleeping giant, nature, awakens and many animals we label as pests renew their cycle of life, and the demand for our services increases exponentially.
It is important to recognize that most of the pest problems confronting our customers arise from the exterior of the structure and the earlier we attack the perimeter the easier it is to keep the problems in check. As pest populations increase it becomes more difficult to manage them at acceptable levels because they expand their niches, and their sheer numbers can become an obstacle to their long-term control.
Hodge (1911) gives one of the most dramatic examples of an insect’s (the house fly) capacity to reproduce. Based on the capacity of a single fly to lay 120 to 150 eggs per batch and a minimum of six batches at three- to four-day intervals, he concludes: “A pair of flies beginning operations in April may be progenitors, if all were to live, of 191,010,000,000,000,000,000 (191 quintillion 10 quadrillion) flies in August. Allowing one-eighth of a cubic inch per fly, this number would cover the earth forty-seven feet deep.”

KEYS TO SUCCESS. While we are unlikely to encounter anything this extreme in the field, pest populations can explode. Because insects are greatly affected by environmental conditions they have a relatively short period of time to exploit the resources the environment and the season have to offer, and once these change and/or are depleted, they seek out more consistent human environments that are readily available to them. The keys to offsetting pest problems are to act early, alter their environment, deprive them of the human environment, and attack the perimeter before they have a chance to multiply and enter structures.
It is much easier to manage insect populations as they begin to expand in the spring as opposed to waiting until their numbers are reaching the carrying capacity of the environment. The good news is you and your customers can have a direct impact on the carrying capacity of the environment. Foundation landscape plantings are probably the greatest attractant for pest insects because they typically offer everything the expanding population needs including:
• Food – Many plants offer a wealth of food to insects, e.g., pollen, nectar, sap, and foliage. One of the major sources of food on these plants is provided by non-structure invading landscape pests that not only serve as a major food source (protein and fats) for predatory pests such as ants, but also are food processors converting plant juices into honeydew (a sugary carbohydrate excretion) that can serve as a substrate for mold – powdery mildew, another food resource. 
• Moisture – Landscape plants around the foundation do not produce water but cause it to be applied liberally next to the foundation, simply because property owners do not want to see expensive landscape plants die from lack of moisture. Furthermore, to retain more water, mulch or other moisture-conserving medium is liberally applied around the foundation and the base of the plants – in some cases creating an impervious interface between the surface and the soil. Landscape plants conserve moisture and create a cool environment by the shade that they offer.
• Harborage – As previously mentioned, ground covers and plants themselves offer pest harborage. But more importantly hardscape items, e.g., rocks, statuary, furniture, downspout splash blocks, landscape timbers, etc., offer a wide array of harborage to insect pests.
So what’s a PCO to do? You can’t expect your customers to totally eliminate landscaping from the perimeter of the structure. However, you can advise them on techniques to appropriately manage this environment, minimizing pest problems by stressing the population. For instance, thinning the mulch layer, reducing water applications, allowing air to circulate under hardscape items, and replacing landscape timbers and other wood with synthetic materials are control options PCOs should consider when attacking the perimeter.

CHOOSE WISELY. The selection of plant materials around the perimeter also can be a factor (i.e., using plants that are insect and disease resistant) in reducing pest pressure around the perimeter. By minimizing aphids, scale, whiteflies, and other honeydew-producing insects and the associated powdery mildew, the perimeter will be much less attractive to perimeter pests.  In cases where these attractive conditions exist, washing the plants periodically throughout the growing season will remove much of the sugary secretions produced by these insects.
Ants are one of the best examples of a group of insects that take full advantage of what nature and the human habitat described previously have to offer. They have a distinct advantage over many other groups of insects in that they are social insects that work together for the betterment of the whole.  In part, this works to their advantage but there are elements of their behavior that can also work against them.
One of the keys to their success is their ability to find and exploit resources through the use of pheromones. Once a food and/or water source is located, the line to the food forms and may extend hundreds of feet ferrying supplies back to the colony.  The downside for the ants is that liquid and granular baits, as well as non-repellent insecticides also can be transported unknowingly back to the nest, resulting in colony destruction.
Insect habits and behavior are significantly affected by the time of year and the availability of nutrients, thus you must remain aware of these changes and how they affect the products you use and the method of application. For instance, baits, liquids and granular products can be very effective against foraging insects and surface feeders.Non-repellent insecticides may be equally effective against these types of insects, as well as those that spend most of their time under protective layers.  Products that tend to have a repellency factor can be very effective on the perimeter in keeping pests away from the foundation.
The product formulation is another important factor for pest control technicians to consider. Granules applied to the soil can provide long-term control but in the absence of water they are relatively ineffective;  whereas liquid applications are less durable but provide immediate results, particularly on direct contact.
All too often our initial inclination is to go after most pests from inside the structure.  Undoubtedly this provides some degree of success,  but rarely does it solve the problem.  Attacking the perimeter provides what you and your customer want – a longer term solution to their pest problem.

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.