Pest behavior so critical

Why is understanding pest behavior so critical? Dr. Bobby Corrigan explains why pest professionals need to be keen observers in the field.



October 2, 2020
Bobby Corrigan, Ph.D.

© macrovector | Adobestock

“To the lazy hunter, the woods are always empty.”

— E.O. Wilson


The structural pest management industry is comprised of two major branches: science and business.

On the science side of our industry, there are about 250 pest species, give or take a few depending on where you live. The majority of the services offered across all those species occur within six pest groups: ants, cockroaches, rodents, flies, occasional invaders and termites. Among those groups, most full-service pest management companies address between 12 to 25 different pests, depending on the season, local pest populations (e.g., carpenter ants in the Northeast, scorpions in the Southwest) and periodic outbreaks (e.g., bed bugs).

© Tim Bradford

On the business side of the industry, there are the obvious components of sales, service, routing, staff, equipment, technology, safety and so on.

Of course, both branches are essential within the pest management industry. But “pest” has always been the first word in the name of our industry. The business of pest management and everything our industry is based upon is supported by one solid foundation: pest biology. From there we get to reap the benefits of a successful pest business such as profits, jobs, growth, good salaries, service and so on. But none of those good things can follow without first the knowledge of biology. In our unique industry, if we fail at the biology, we fail at the business.

So in a very real sense, every pest professional arriving at any client’s residential or commercial property is, by default, an on-the-job biologist regardless of possessing a university biology degree. This should be evident by noting that the majority of global conventions, annual state association meetings, certification exams, company trainings, correspondence courses and so on place the heaviest emphasis on the science (pest biology) side of things.

As pest professionals, we are bound by two aspects of pest biology: 1) life cycles and 2) pest behavior. Both are important. But behavior is often the more important of the two because it regularly varies from client to client on pest service routes, whereas the life cycle of the same pest species remains similar even in different parts of the world. A house mouse inside a home in Missoula, for example, can behave different than a house mouse in a Missoula convenience store only two blocks away. Yet these two mice generally will exhibit similar gestation periods, offspring, life spans, fecal output, etc.

This is because pest behavior is many times dependent on site-specific factors, such as what is on the exterior of the building (e.g., undeveloped areas, any nearby water, plants, trees, landscaping, tidy or untidy neighbors, etc.), the building’s construction (e.g., block walls or poured cement), temperatures, humidity levels, the maintenance (pest proofed, sanitation levels), to mention but a partial list. But, the bottom line here: It is the practical on-the-job observations of these factors matched to the pest’s behavior at that site that enables you to provide quality prevention and/or control of any of the previously discussed invading pests. Most clients assume this on-the-job knowledge and “best practice” is simply a “given” within the service they have purchased (although we know there will always be some who think we just have some “magical spray”).

OTJ OBSERVATIONAL BIOLOGIST. “Looking” at something is not the same as “observing” something. Looking at something is passive and doesn’t require much — or even any — energy or thought.

To observe something (e.g., an ant infestation in a house) requires concentrated thought with attention to any one or more of several factors that enter into a client’s pest problem. Being observant is like “looking on steroids,” which is a very active process.

Scientists and philosophers have long stressed how being observant is the “secret of secrets” to problem solving. The 19th Century Oxford chemist Benjamin Brodie famously advised: “In observation lies the source of genius in discovery. It was keen observation — not machines or technology — that steered Isaac Newton to explain gravity and Will Harvey to prove the circulation of the blood.”

Your client asking, “What do you see?” is very different than the client saying, “Please explain to me what is going on here.” That difference is the difference between a technician looking around for spots to “treat” with a product versus an observational biologist trying to figure out if he or she needs to treat with a product, and if so, specifically where and how.

This bait station is simply positioned next to a wall. But it would be far more effective had it been installed only several feet away within the shadowy, low-lying bushes (i.e., the natural cave-like area) that rodents prefer to hide within and explore.
Photo courtesy of Bobby Corrigan

KEEN OBSERVERS. Notice that Dr. Brodie used the phrase “keen observers.” Time and time again, this phrase is tagged to medical doctors, detectives, physical therapists, poets, scientists, naturalists and others. The word “keen” is essential in all this; in fact, “keen” drives the entire premise. Forgetting your occupation for a second, if you are “keen” on doing something, you very much want to do it. If you are keen for something to happen, you very much want it to happen.

So let’s put the power of keen observation to work on an everyday pest route using three typical jobs: 1) ants 2) exterior rodent stations and 3) German cockroaches.

Ants. As you likely already know, ants are among the most successful animals on planet earth. Some pest species can pose real challenges and profit-eating callbacks. Consider for instance, carpenter ants and odorous house ants.

I once accompanied the beloved myrmecologist Dr. John Klotz of the University of California for a nighttime ant safari while we were both working at Purdue University. John taught me that to understand ant problems around homes and yards, you should first keenly observe the specific “lines” that exist for a particular property (see image on page 38). That night John gave me a short course in what I jokingly termed “lineology.” John pointed out the linear edges of the sidewalks surrounding the house, the edge lines of mulched gardens and landscaping, driveway edge lines leading into garages, overhead utility lines connecting to attic soffits, air conditioner lines penetrating siding and the vertical edge lines of the bark of old oak trees.

Using an example of the often onerous odorous house ant, John explained that one secret for minimizing callbacks of OHA was to carefully observe and pinpoint all the honeydew sources nearby the home and connect those sources to the structures via any of the structural lines I observed. He taught me how carpenter ants from nearby trees can send out scouts that travel hundreds of feet along various structural orientation guidelines to enter any number of places into a home.

My John Klotz course in lineology was a game changer in my life. I never dreamt there could be so much to observe around what until then was to me just an “ordinary” suburban house. Years later, I realized those same behavioral principles of lineology applied equally well to my own science of structural rodentology. Rats (especially roof rats!) and mice also take advantage of the efficiency of structural lines to commute to and from resources (see image on page 38).

The practical “take home” is this: A fundamental key for the most effective applications of sprays, baits, rodent stations and other equipment begins with keen observation.

Exterior Rodent Bait Stations. Our industry commonly installs bait/trap/monitor stations on building exteriors. These stations are important tools to protect structures from rodents. But whether or not these exterior rodent stations actually offer that promised protection (versus merely looking like some magical “ring of protection”) primarily depends on the observations of the pest professional. He or she needs to first observe those specific spots along the exterior that we know from rodent biology research to be rodent-attractive versus blindly adhering to the old myth that rodents must “hug walls” because they can’t see well and as a result always enter any “wall hugging stations” encountered.

In actuality, rodents typically explore areas along building exteriors that provide protective covers, shadows, overhead touch feedback, warmth or coolness, areas in close proximity to some food or water resource, pheromone trails from other rodents and more. In other words, rodent equipment installments depend almost entirely on the observational biology foundation. Frankly, anyone without any rodent training can follow an instruction sheet out of the box to “drop” a rodent station every 25, 50 or 75 feet around a building’s exterior foundation walls. The only training one needs for such a service is a tape measure. (EPA rodenticide labels and some food plant auditors certainly have a way to go in updating such non-scientific application directions.)

German Cockroaches. Over the past several years, some extraordinarily effective German cockroach baits have emerged. But similar to the rodent equipment installment principles just mentioned, a great roach bait applied into an “amateur’s spot” will be, in fact, a poor-performance bait.

To achieve the quickest and most sustainable control of roaches with baits, they need to be placed as close as possible to the cockroaches’ harborages. The science of cockroach behavior has taught us that German cockroaches seek out available narrow/tight cracks and crevices (3-9mm height/width) in locations that are warm, humid and nearby a water source (all simulating their tropical jungle origins). If those crevices also occur within a wooden element (the walls of a sink cabinet) or within the corrugation of a forgotten piece of cardboard on top of a cooler, all the better for a prime harborage. So standing in some commercial client’s kitchen holding a bait applicator of a great bait and equipped with that modicum of cockroach biology, coupled with some keen observations, renders a good chance of success versus “caulking the bait” into any easy-to-reach crevices and hoping the roaches will eventually “find it.”

A keen pest observer also would take note that when they spot small roach nymphs, they need not go further than their arm’s reach to where the harborage associated with that cockroach is likely to be. Such an observation provides a handy “GPS pin drop” for the next few minutes of baiting.

OTJ TIPS. We are born to be able to see and look at things with our eyes. But we are not necessarily born with good observational skills. Becoming a keen observer requires practice (not only in pest management, but also in our everyday lives).

When on the job, constantly remind yourself to be active, not passive. Are you merely looking around with your flashlight, or do you actively concentrate on being observant? The fact of the matter is that on any given pest route, very few things are “easily seen.”

For any of the 250 pests or just among the “Big 6” discussed earlier, ask yourself: “What key biology words define the behaviors of this animal?” Those words can serve as concentration points for making keen observations. Using our three pests for examples (and you should be able to add your own based upon field experience):

  • Ants: Structural guidelines, food honeydew resources, water drips or pooling horizontal and vertical trails, edge lines.
  • Rodents: Shadows, corners, lines, warmth, sebum smears, tight spaces (12mm and less) below and between objects, low-lying hard-to-reach spaces.
  • German Cockroaches: Warmth, humid, wood, 3-9mm crevices, water sources, hard-to-reach areas, overlooked stationary cardboard.
Regardless of how good any cockroach bait may be, proper placement based on keen observation will determine a bait’s success.
photo Courtesy of Bayer

Being a keen observer is not defined by equipment. The brightest, coolest flashlight — although a very important inspection tool — will not teach you the lessons or the power of observation. Easily 90 percent or more of being keenly observant occurs without any equipment whatsoever. But equipment can often help to provide that crucial 10 percent confirmation that your observations were spot on.

SUMMARY. We can surmise that pest professionals who are keen observers can be described as those who very much want to discover via skilled observations the sources and reasons for a specific client’s pests, which in turn will provide sustainable control. Since that is what our clients expect, are paying for and will be 100 percent satisfied when provided, it reveals the essential components of our pest management industry: the partnering of good science with good business.

In closing, let’s return to the legendary observational biologist E.O. Wilson and his overriding daily question: “So what are you discovering in your client’s woods?”

Author’s note: This article is in honor of John Stellberger of Environmental Health Services of Norwood, Mass., who built his highly successful IPM company based on his dedication to the principles and practices of observational biology.

The author is an urban rodentologist based in New York City.