When prebaiting for rats, don’t limit the bait to just one choice for the rats. Expect a picky eater to be in the bunch; you don’t want to miss trapping the rat that continues to reproduce.

In the city of New Orleans, rats face a formidable opponent. Timmy Madere, special projects coordinator for the City of New Orleans Mosquito & Termite Board, is an expert in urban pest issues and rodents. When the call for help goes out, he relies on tracking, trapping and technology to rid buildings of rats and mice. In PCT’s Rodent Control Virtual Conference hosted late last year, Madere shared techniques that pest management technicians can use, guided by old school Sherlock Holmes observation skills and technology tools.

DETECTIVE WORK. Madere has learned through extensive field and research experience that successfully tracking and trapping rats begins with detailed detective work and an open mind. Sherlock Holmes inspires many throughout the pest management industry and is famous for his detective approach, emphasizing thorough inspections using observation, reason and logic. Looking closely at all the evidence before making assumptions — the difference between simply seeing and observing — also is key to helping technicians determine the source of rodent activity and set the course for an effective rodent control program.

A recently encountered trash can reinforced this point for Madere. The can had become a convenient food source for rats and it would have been easy to assume rodents chewed their way into the trash can through the bottom. However, after close inspection, small scratch marks were discovered in the sides of the plastic trash bag leading out the top of the receptacle. They revealed the rat was entering and exiting through the top of the trash can, not the bottom, and it was found sitting inside. Had the scratch marks gone unnoticed, traps placed underneath the can may have never solved the issue.

In another case, similar observation techniques were combined with technology to gather detailed evidence used in solving a basement rat problem. Droppings found around a sewer pipe suggested rats were traveling into the building through the open pipe. Building engineers resisted, not believing rats would use a pipe connecting to sewer water as the entrance or escape route. Madere installed a camera and with video footage of a rat poised on top of the open pipe, he quickly made the case to the client to plug the hole.

TRACKING. Madere stressed that tracking rodents requires paying close attention to detail. Rats and mice leave behind many clues through odor, urine, droppings and rub marks that help technicians determine their presence, the species of rodent and the best placement for traps or stations.

Rodent odor is often the first clue to reach our senses. Madere suggests getting familiar with the unique scents of roof rats and Norway rats by putting their bedding into jars and using the jars as a training tool. He says this technique is effective for cockroaches and bed bugs too; he often will know the pest he is dealing with by walking into a room and taking a whiff.

Rodent species also can be narrowed down by taking a closer look at the shape of the droppings. Norway rats have droppings the size of raisins; roof rats are smaller and have a distinct hook. Even smaller — about the size of rice — are house mouse droppings, which are characterized by hairs that can be seen using a hand lens.

Wherever they go, rodents mark their routes with droppings, urine and rub marks (sebum) as evidence. Before placing traps along these routes, knowing if the route is still in use can save technicians time and frustration. One trick Madere finds useful is leaving his own mark by scratching into sebum rub marks. If the scratches are rubbed over a week or two later, he knows rats are still using the run. He also appreciates advancements in products like monitoring blocks that give droppings a fluorescent color, alerting him to fresh droppings. Non-toxic fluorescent dyes dusted inside rat burrows help Madere understand foraging routes. He also uses different dye colors to detect colonies with shared food sources.

Through experience, Madere says it is not uncommon for species to share paths, contrary to some thinking. He has observed rodents intermingling when the food source is abundant.

“We’ve seen evidence of mice, roof rats and Norway rats in the same area and it even appeared that they were eating in shifts,” he said.

Technicians expect to see rats traveling along lines, shadows and walls. Madere cautions PMPs to watch for exceptions. Sometimes rats come away from the wall, perhaps for no obvious reason.
Janet Hurley, Bugwood.org

Another rodent behavior technicians expect to see sometimes is for rats to generally travel along lines, shadows and walls. Madere cautions trackers to watch for exceptions. Studying rodent urine trails identifies places where rats are coming away from the wall, perhaps to avoid a gap or for no obvious reason. In those situations, it may not make sense to follow traditional best practices of placing equipment against the wall. Moving traps or stations into the path away from the wall may be the best strategy for getting contact with the rat.

Tracking rodent trails through dust and sand can literally mean following their tracks. A close look at prints in the dust can point in the direction the rodents are traveling, the route they are following and where to continue your tracking efforts. When he can, Madere shows footprints to customers and points out the telltale outline of four toes on the front feet and five toes on the back feet.

Once rodents have been thoroughly tracked, information gathered about their habits and travel patterns can be used to develop a strategy for trapping.

TRAP PLACEMENT TIPS. Why wait for a rat to discover the trap when success can be achieved faster by bringing the trap to the rat? Using observation skills or technology such as video or sensors, PMPs can locate lines, shadows and other paths rats use to move around an account. It may take creativity to find ways of placing traps in their route. If rats are climbing on a roof to feed on pigeons, try attaching traps to tree trunks. Modern plastic traps or classic wooden Victor traps can be anchored to pipes or beams in almost any angle or direction using zip-ties.

Another effective placement technique leverages rats’ instinct to run and follow the trail of pheromones left by other rats. Madere sets traps perpendicular across runs to catch rats as they run by. Their body passes over the trigger mechanism to be caught by the bar rather than just a head or foot when they are stopped reaching for the bait to feed.

PREBAITING. “If you’re not doing prebaiting, then you’re not doing trapping right,” Madere said. He explained that investing a few nights of prebaiting before active trapping dramatically improves catch results. “Otherwise you’re only pulling out one or two animals at a time.”

Rodents are weary of new food and objects, a behavior called neophobia, causing them to shy away from traps initially. Prebaiting is a way of overcoming neophobia by rewarding rodents with food. Madere makes note of what rodents are eating at the account and prebaits using the food they prefer. He offers eight tips to ensure a successful prebaiting strategy:

  1. Eliminate or at least limit all other food sources.
  2. Use four to five kinds of bait. If you plan to use 100 traps, try 25 traps of peanut butter, 25 traps with apples, 25 with tuna fish and 25 with dog food or beef jerky.
  3. Be generous with the amount of bait to feed as many rodents as possible.4. Add additional traps in areas with a lot of feeding.
  4. Narrow the choices to the best performing baits.
  5. Don’t limit the bait to just one choice for the rats. Expect a picky eater to be in the bunch. Chances are that picky eater may be a pregnant female or dominant male and you don’t want to miss trapping the rat that continues to reproduce.
  6. Don’t forget to empty and rebait the traps with fresh food.
  7. Plan to prebait traps for three to four days. Madere continues prebaiting until 75 percent of the traps are cleaned out.

When it’s time to start active trapping, use the opposite approach with bait. Madere recommends loading up the trap with generous amounts of bait when prebaiting. For active trapping, use a small dab of bait placed at the back of the trip plate. The scent of the bait will attract the rat but because it’s only a small dab, the rat will need to lean far into the trap to reach it. The less food on the trap, the more the rodent has to interact with the trigger mechanism, he says. slow and steady wins. Madere says applying technology in rodent tracking and trapping strategies may not solve problems faster, but it does provide notable benefits.

Technology enables technicians to continue monitoring for activity, even when they are servicing other accounts. Cameras and sensors capture activity for review at a later date, often in less time than it takes to observe the activity firsthand. In just one photo, Madere identified the species of rat, the pipe it was climbing to the ceiling, and the exclusion work necessary to close the hole and prevent the rat from entering the room again.

“I can’t be in the alley or in a kitchen 24 hours a day so these things are helping me put forth less effort but still do a better job,” Madere said.

Technology also helps technicians see rodents that may be difficult to find with the naked eye. There are some infrared cameras that attach to mobile phones and an app helps technicians see hot and cold spots, like rodents running through ground cover in landscaping. This is particularly useful at night when they are the most active.

House mice leave behind many clues through odor, urine, droppings and rub marks that help technicians determine their presence.
Wikimedia

“This will help you follow the rodent back to where they’re entering and exiting so you know where to focus exclusion work and where to place your traps, sensors or cameras,” Madere said.

Like traps and bait stations, cameras and sensors require planning to be effective. Using good tracking skills to identify where rodent activity is occurring is key to using cameras and sensors effectively. They need to be installed in the right location and PMPs should expect that it may take some practice.

Madere learned enough that he shifted his approach to using cameras before putting out traps or stations. The cameras provide information he didn’t have access to before through observation. When evidence points to active rodent activity, the cameras sometimes tell a different story.

“We are putting out cameras before anything else so we know exactly where our hot spots are. Droppings are not going to tell you how long they’ve been there or if this is still an active trail. Maybe the food source was taken away or the water source went away. Maybe they just decided to quit walking in that direction. Everything told us rats were there but once we put cameras on watch for a few weeks, we saw the threat never traveled that way anymore.”

Another technology benefit is the ability to provide concrete evidence that a rodent program will be or was effective. As a selling tool, prospective customers may be more willing to buy knowing you have technology tools to validate the service. After the sale and after the infestation is resolved, even the most experienced technician may have trouble convincing a customer their approach worked to end the rodent infestation. Video or data collected by sensors showing the absence of activity can be an effective means of providing proof.

FINAL THOUGHTS. Training technicians to be keen observers during trapping can help them investigate small details and be more efficient managing their routes. “We’re looking for trifle things other people would overlook, such as a red drop of blood,” he said.

Madere shared the story of finding a drop of blood on a trap. Knowing the rat was injured prompted the technician to look around the trap area and find the dead rodent, avoiding a return trip back to the account later. Finding whiskers caught in a trap or glueboard also can signal trouble. If the whiskers go unnoticed, the technician may not understand why the trap isn’t getting activity or think to start over with prebaiting to coax the rodents back.

Carrie Thibodeaux is a Tacoma, Wash.-based freelance author who has been writing about the pest management industry for 20 years.