High-Tech Rodent Control

If you’ve experienced the challenge of a difficult pest control situation that you successfully resolved, then you understand the personal reward of knowing you’ve provided valuable help when your client and colleague may have needed it most. We might argue that vertebrate pest control situations are much more interesting and challenging than typical "bug" situations for a variety of reasons, including the higher intelligence and capabilities of the target pest animal. Of these, rodent control situations offer many degrees of difficulty and these situations can be a stringent test of your pest control skills.

GUESTIMATING POPULATIONS. The Norway rat (Rattus norvegicus) and roof rat (Rattus rattus) are significant adversaries that man has been battling for centuries. In some U.S. cities, there are those who would say it appears we are losing the rodent war. Despite the many weapons within our rodent control arsenal, rats remain some of the most serious pest problems we deal with as an industry. And, often times, we may find ourselves called in to deal with an "out of control," hopeless or severe rat control situation with no positive resolution in sight (rather, not in sight to the naked eye).

The time-proven methodology of performing a thorough inspection, assessing the situation and formulating your action plan is a sound approach to any pest situation and rodent control is no exception. However, experts agree that accurately estimating the number of rodents present at an account can be a tricky business.

The one thing that may be universal in pest control is that pest professionals continue to be confounded by pests and their ability to ignore various published maxims regarding their abilities and normal behaviors. For example, if we plugged in the aforementioned estimation formula, we would have estimated that some of the areas at a rat-infested account held about 24 rats (we later found out this estimate was off by more than 100 percent…keep reading to see what I mean).

Of course, local conditions at any account play a significant role in the accuracy, or lack thereof, of the above-mentioned formula. Field conditions at an account may dictate that the number of burrows present may be drastically different that one might expect under "normal" or "typical" conditions as found in industry references. After all, pests don’t read this magazine.

COUNTING RODENTS ACCURATELY? Is there a viable way to accurately estimate or count the number of rodents present at an account or in an infestation? Is there an easier way to get a better estimate than using a formula or simply guessing? Can we count the number of droppings found and divide by the "average" number of droppings a rodent produces per day to yield a number of rodents that is anywhere close to the actual number? Is there a method we can use to give us a reasonably accurate estimate of a rodent population? Well, thanks to technological advances, there is a simple way — via thermal imaging (or infrared) technology.

Researchers in many disciplines may use various measurement and counting tools. Some of these tools may be as simple as digital "clicker" counters where each individual item counted is recorded by pressing a button (much like golf stroke counters). Logically, we might agree that we could accurately count the number of rats in a given infestation by discretely setting up in a suitable observation location and counting each rat seen after dark. It would work if you could see every rat and they would stand still long enough to be counted. Therein lies the trouble — they don’t stand still and rats can be difficult to see after dark, even with night vision equipment.

HOW DO THEY WORK? Simply stated, infrared cameras are instruments that are capable of measuring temperature. Specifically, they detect and measure heat. They work by being able to detect slight temperature differences between surfaces and converting these differences into electronic signals that are then transferred to a viewing device, such as a computer monitor or LCD screen, creating a viewable thermal image. The temperature differentials these devices can detect are slight, with higher temperature items appearing brighter.

Infrared technology has many uses today. Many units available are intended for use in "predictive maintenance" where engineers and equipment maintenance personnel inspect various forms of equipment with thermal imaging devices. Equipment found to be operating at a higher than normal temperature is further inspected and repaired prior to failure. Such "predictive maintenance" applications produce significant savings in repairs and lost production time.

Thermal imaging is also used by firefighters, search and rescue personnel, police, security, agriculture and the military. Infrared allows firefighters to see through smoke to rescue victims and other firefighters. Firefighters also can use infrared to spot hot spots in large-scale brush and forest fires while also being able to identify safe routes of travel and other information that helps them plot their fire control strategies.

Through the use of infrared, search and rescue teams can spot victims at great distances over vast terrains. Police use thermal imaging to help spot perpetrators. High-tech infrared can see various targets — where they are and where they’ve been as well. Versions of such technology now are available to the pest control industry.

PEST CONTROL APPLICATIONS. Although infrared equipment may be expensive, its value and utility for pest control applications offers great and significant potential. As previously mentioned, all things emit infrared energy and the hotter an item is, the brighter it appears as a viewable infrared or thermal image. When viewing an infrared image you are able to see vegetation, trees, buildings, telephone poles, etc. These objects appear as various shades of gray, similar to a black and white television. But a live animal, such as a person or a rat, appears bright white and is easily seen on an infrared view screen (computer-enhanced color thermal imaging is available at an additional cost). In fact, it is difficult for a rat to hide from infrared at all. Remember, infrared "sees" heat and as long as the rat’s body temperature is above its surroundings then it is plainly visible to an infrared camera.

SEE LIKE SUPERMAN. Yes, in many ways infrared allows you to see like Superman. But even the "man of steel" had his limitations. Infrared detects heat and even though it can "see" through smoke, clear or black plastic, foliage and other materials, it cannot see through any material through which heat will not pass, such as glass. (Hey, what do you want? Even Superman couldn’t see through lead!)

But do not discount the value of thermal imaging devices to detect or see differences in heat or "heat signature" and the temperature differential or sensitivity of these devices can be amazing. Even though active rodent burrow openings appear to glow in the dark due to the heat, you’re actually seeing heat where the rodent was. Additionally, rodent nesting areas may be detected behind, beneath or through various materials and substrates. Rodent burrows behind concrete block, above drop ceiling tiles and beneath leaf litter and landscape debris may be detected because of the heat (infrared) energy they emit.

HOW IT WORKED FOR ME. This article began by raising a few questions about accurately estimating rodent (specifically Norway rat) populations. We made arrangements to visit a client’s facility after dark and use an infrared camera to observe the rodent infestation. The purpose was to get a better idea of what we were facing and learn as much information as possible about the habits of the resident rat population that might be used to prepare a sound control program.

A few key pieces of information were gained as a result of this process. Note the following:

1. Rats are totally unaware of infrared technology. As silly as it may seem for me to write and for you to read, rats don’t know beans about infrared, thermal imaging, the visible or invisible light spectrum. This is readily evident because I found that rats think you can’t see them in the dark. In actuality, you can see them easily as they virtually "glow in the dark" with the aid of the IR camera. It’s surprising how close you can walk up to a rat that thinks he is well hidden under the veil of darkness. How close you might ask? You better have good work boots on and your pants tucked in tight.

Additionally, because it’s a reasonable assumption that the rats think they are well hidden by darkness, they go about their nocturnal business as usual. This means you can see where they travel, identify food preferences and determine how many rodents are infesting a particular area. These are all good bits of information that will help you piece your pest puzzle together, and plan and implement a successful rat control program.

2. The estimate formula may be a tad off. In the left-hand photo on this page, you’ll see about 48 rats (you’ll have to trust me, I was there). However, we only counted nine burrow openings in this area. Had we depended upon the previously mentioned formula, the math would have been: (9 burrows / 3 openings per burrow) x (8 rats per family) = 24 rats. That’s half of what we actually counted. Further, we can assume that only those rats mature enough to leave the burrows were seen. As such, it may be fair to state the actual population, inclusive of pups, was significantly more than the 48 counted.

3. Are rodenticide labels correct? If we look at item #2, we learned there were many more rats than the number of burrows would seem to indicate as per the estimation math model. However, rodenticide bait product labels may limit the amount of rodenticide that can be placed within a burrow. (Perhaps the amount is insufficient to control the number of rats actually present?) This is an interesting topic that may warrant further investigation.

4. Rats might move right in close to the food resource. At the situation in question, there were several animal enclosures that were being invaded by rats. The original thinking was that the rats were marauding from outside and adjacent areas, waiting for the cover of darkness to hide their midnight raids on surplus animal feed and remnants present within the various animal enclosures. The IR observation revealed that this was not the case. In fact, it was estimated that more than 90 percent of the rodent population had established residence within the animal habitats and seldom left the protection of these enclosures.

Why would they? They had every resource they needed within the habitat: food, water, shelter and they were protected by the very enclosure bars and fences they invaded. The remaining rat population that lived outside these habitats were likely either "omega" or surplus population members. Think of the significance of this factor alone. Prior to this observation, numerous control devices were placed outside and along the exterior edges of the habitats and few rodents were effectively controlled simply because there were few rats present outside the habitat boundaries. The control measures were placed in the wrong place.

5. If you can’t count, you have the tape. Even though you have a hand-held counter, you may find that you miscounted or are unsure about your counts. It’s difficult to count rats accurately as they scurry about at night. However, if you have the videotape from the IR camera then you can review it to become more comfortable with your counts and estimates. The tape may be paused and counts made if necessary.

6. Norway and roof rats co-habitating. One account location was in a region of the country where both Norway and roof rats are found and we observed them co-habitating in harmony. Aggressive behavior may normally manifest itself when resources become limited relative to the rodent population. Rodent resources at this account were not limited and this may have been one of the contributing factors why these rats were observed together with no aggressive behavior demonstrated.

7. You can see where they live. As mentioned earlier, areas where rats travel and nest may be visible due to the heat residues detected by the infrared camera. Rodent nesting areas are able to be seen behind concrete, ceiling tiles and foliage. A rat well hidden behind thick weeds or grass is invisible at night with the aid of the best flashlight but is readily seen as a glowing white figure in the thermal imaging view screen. Roof rats may be seen foraging in trees as well.

8. Let’s go to the video tape. Just like NBC’s Len Berman, you have the tape and there’s little arguing with the videotape. That’s a huge advantage. You can be the smartest and most educated person in pest management but seeing is believing. Even though you’ve correctly informed your client about the extent of their rodent problem and the necessary measures needed to bring their problem under control, the tape will go a lot further in helping you successfully educate them about their problem than you can alone.

9. Let’s go to the video tape, again! That’s right, you have the tape and once you’ve used the tape to demonstrate the severity of the problem, you can also use your follow-up tape to show them how well your control program has succeeded.

PRACTICAL ISSUES. There are a number of pest professionals successfully using IR technology for termite, pest and structural inspections and it appears this use will become more widespread as the industry embraces new technologies.

Interested in becoming a high-tech rodent sleuth? Well, bring your checkbook and pack a lunch ’cause it’ll cost you to play in the infrared game. Infrared cameras or thermal imaging devices can be costly. The current model used to create the photos in this article goes for approximately $14,500 (yes, that’s for one) and other units are available for as much as $70,000.

Editor’s note: Visit www.pctonline.com for additional information about various infrared camera manufacturers.

The author would like to thank Doug Mills of Liphatech and Mike Larson of IR Cameras for making this project possible. At the time of this writing IR Cameras was the sole developer of the equipment with combined capabilities of thermal image viewing, still photos and digital video taping in an affordable unit. For additional information visit www.ircameras.com or www.liphatech.com.

The author is owner of PJB Pest Management Consulting, Alpharetta, Ga. He can be reached at pbello@giemedia.com.