Are we in for a very busy rodent season?

Krissie Callahan

Rodents have been making headlines across North America in recent months. Larger-than-usual populations of rats and mice have been reported across the country this spring and summer, and that could spell trouble for businesses this winter. 

Heading into Memorial Day weekend, the headline trumpeting across the New York Times was one that made even the toughest city-dwellers shiver: Rats Are Taking Over New York City

The story is similar in Los Angeles. Rats have been prevalent and several cases of bubonic plague have been confirmed, spread by fleas that feed on rats. Recently a report put together by public health experts there asked Governor Gavin Newsom to declare a rodent-related public health crisis across the entire state. 

Chicago also recently enacted new initiatives to battle rats. 

Still, other cities and towns are seeing unprecedented mouse and rodent populations. 

What is driving all of this rodent activity? Rentokil’s experts from around the country weigh in with their opinions. Find out what they are seeing to be prepared for what could be a very active rodent season this fall. 

rat on wood structure

Why rodent populations are booming

“Over the last three years, we’ve had a lot more persistent issues with rodents throughout the entire year than I’ve seen in previous years,” says Chad Gore, Ph.D. and Entomologist with Rentokil. “We’re seeing more rodents right now during the warm season – the time of year when these pests are reproducing at a normal to fast rate. So we can expect a bumper crop of rodents in the cooler months.” 

There are multiple reasons behind the uptick in activity that we can explain, says Gore. 

  • Warmer winters
  • Construction in existing urban areas 
  • Land development


Warming winters and rodent populations

In general, the average winter temperatures have been rising steadily in the United States. In 2019, the average winter (December – February) temperature in the contiguous states was 33.4°F, more than a degree above the average. That is a trend that has continued over previous years.

A warmer planet is contributing to plentiful pest issues – and rodents are just one of them.

“Without really cold winters to create a natural population-check that allows for die-off and stops some rodents from reproducing, there will be more rodents reproducing for a longer period of time – and that means population growth,” Gore reports.  “Given the opportunity to find shelter and food, they will, and that’s often in businesses and homes. There, temperatures are cozy and food sources plentiful.” 


inspecting business for pest entry

What businesses can do now to stay protected against rodents

With rodent activity so heavy in warm weather months, there’s an increased likelihood that the fall and winter will bring unprecedented issues for businesses this fall. 

“There’s a general malaise when it comes to the perception of rodents. People see them as a pest, but they don’t always do the things that need to be done to manage rodents effectively,” Gore says. “To keep a structure from falling victim to rodent invasion, buildings need to be proofed or secured against rodent entry and sanitation issues need to be kept in check.” 

That makes now a great time for businesses to inspect their buildings. Business owners should also sit down with their pest management provider to review their rodent programs. Take time to identify potential gaps in the program. Closing those gaps now, before cooler weather arrives, will minimize the chances that rodents can gain access to a property. 

  • Review any changes to the structure or operations since last winter. Any areas that have been subject to construction or renovation since last winter may be at increased risk for rodent activity. Construction projects often leave structural gaps that can allow rodents to gain entry. 
  • Before the first frost, do a thorough exterior inspection and patch up holes and cracks. Remember, mice and rats can gain access to a structure from the smallest of holes – smaller than you might imagine. Holes as small as ¼-inch can give a mouse enough room to wiggle inside; rats don’t need an opening much bigger. Pay special attention to gaps where pipes and cables enter buildings. Fill them with pest-proof material such as 1/8-inch wire mesh, flashing, hardware cloth, or silicone caulk. 

“Remember to look high and low; look for potential access points from the rooftop to the gutter line to the foundation,” Gore reminds customers. “Norway rats and house mice tend to be ground dwellers. However, they are agile climbers that can and will climb up surfaces, even a brick building face.”

  • Scheduled preventative maintenance. Preventative structure maintenance should be done on a prescribed schedule. Too often businesses leave preventative building maintenance as something that is done when it can be fit in. Unfortunately, that leaves plenty of opportunities for problems to go unchecked. Making it a scheduled task means that it takes priority, just like other important tasks.
  • Be aware of your environment. “Understanding what’s going on in your environment outside will help businesses stay on top of potential rodent issues,” says Gore. “Be aware of construction on the same block or in your neighborhood. It could create rodent activity.” Alert your pest management professional of any unusual activity so that they can institute protective measures.
  • Practice good garbage management. Trash is a primary attraction for rodent pests. Ensure that all trash is placed in bags before going into a dumpster or outdoor cans. Keep garbage and dumpster areas neat. “Secure dumpsters whenever possible – that means a locked lid,” says Gore. All exterior garbage cans should have covers or self-closing lids to prevent rodents from getting inside. And if you can avoid it, don’t leave bagged trash on curbs. Rodents can easily chew through or tear open bags to access refuse inside.  
  • For businesses that share walls and ceilings, install rodent protection in the ceiling. Rodent pests can easily travel in drop ceilings from one business to another. If you share walls or ceilings with neighboring properties, it’s a good idea to have extra protection in place. Screen vents and talk to your pest management professional about what else can be done. 
  • If your property has seen increased activity this summer, increase your rodent protection. Installing additional devices, such as Rentokil’s Dual AutoGate Connect and Multi Rodent Trap Connect, to help monitor for activity can act as an additional alert system. These internet-connected devices alert to the first sign of activity. This allows you and your Rentokil specialist to take additional needed measures in targeted areas.  
  • Trim back vegetation. This is one of the most simple rodent control measures that can be implemented, but one that often goes overlooked. Trees overhanging rooftops can provide the perfect roadway for roof rats to gain access to a structure’s roof. From there, the can easily find a quarter-sized hole to make their way inside. On the ground, ensure that there is at least an 18-inch vegetation-free zone between structures and any landscaping. Clean out under shrubbery to eliminate rodent hiding places. 

Don’t go the do-it-yourself route

While some businesses may be tempted to try to handle a rodent issue on their own, that might not be the best course of action. Rodent populations can grow quickly. If something goes overlooked for even a day or two, it could mean an even larger problem to handle. 

“I think we are going to be in for a pretty tough fall and winter with rodents,” Gore warns. “I’d caution businesses against going it alone this winter by taking the do-it-yourself approach. Developing a relationship with a pest control professional now means that your business will have a partner in keeping rodents at bay come fall and winter. ” 

For rodent prevention and control that your business can count on, contact the experts at Rentokil.

Krissie Callahan
Krissie Callahan

As the Communications Manager for Rentokil North America, Krissie specializes in writing, editing, and shaping both internal and marketing messages for the company. When she's not at work, you can usually find her taking in a live music performance in her hometown of Charlotte, NC.

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