Rodents at Large (Norway rat, Roof rat, house mouse)

Kristen Stevens, BCE
Corporate Entomologist, Cook’s Pest Control

Cooler Weather Means Rodents Looking for Somewhere to Stay Warm

As cooler weather approaches, so do rodent issues. Rodents, like any other pest, are seeking food, water and shelter when you find them inside your facility. They are there because inside seems like a cozy, great place to seek shelter from the inclement weather. Once they are in, there is a good chance they are going to be a nuisance to get rid of. But first – which rodents are we dealing with?
There are three rodents that are major nuisances and typically encountered in pest management – the white-footed mouse, the Norway rat and the roof rat. The white-footed mouse is also considered a field mouse. They are not a commensal rodent, meaning they don’t prefer to be inside but will live indoors to survive harsh cold temperatures. Instead, they prefer a wooded or brush habitat. They are a small rodent about 16-20 cm long and only weighing in at 10-40 grams. These mice are brown-reddish in color and have white underbellies.

The second rodent we deal with is the roof rat. The roof rat is a slender rat, grayish-black to solid black in color, and their bellies range from gray to white in color. These rats are agile climbers and love to be up high, so they typically nest in high spaces. They love to eat a healthier diet of fruits and nuts if they had it their way.

Finally, the Norway rat, although not as common, presents problems for facilities as well. This rat is a much stockier rat with a course body that ranges from reddish to grayish brown with buff-white under parts. These rats tend to spend time on the ground and nest in burrows. They have a much less healthy diet and eat a lot of grease and meats.

As a source of health problems, rodents are a major pest concern. Some of the health complications that rodents can cause include allergies, hantaviruses and food-borne illnesses. Research has shown that inner-city areas with serious mice infestation issues have been known to trigger asthma and allergies in children living there. It has been found that there is a protein in their urine that triggers these reactions. In homes with numerous mice, large amounts of urine and droppings carrying these proteins would be present. Another health concern associated with rodents, specifically the white-footed mouse, is hantavirus pulmonary syndrome (HPS). It, like allergens, is spread through the urine, feces and saliva from rodents. Finally, rodents have been known to carry food-borne illnesses such as salmonellosis and campylobacteriosis, both of which can cause acute food-poisoning.

Rodents are also an economic issue. Their teeth, reportedly tougher than iron, are extremely strong. So, as you can imagine, they can chew through just about anything. Wires, cables, fences, ceilings, walls, etc. All of this can come as a cost you may have to rewire something or fix electric circuitry, for instance. They have even been known to chew through car wiring! Rodents do a lot of damage and, consequently, do damage to your wallet as well.

So how do you help your pest management professional keep the rodents away from your home or facility this winter? Here is a list to help keep your winter rodent free:

1. Exclusion: Sealing potential entry points is probably one of the most important things you can do to prevent rodents. Rodents have teeth stronger than iron and can chew through a wide variety of material. They also can squeeze through very small spaces. Mice can fit through openings as small as a ¼” and rats only need an opening as large as ½”. It is important to scan your entire building to make sure that all rodent sized openings are eliminated. Be sure to use rodent proof material for sealing any and all openings.

2. Sealing food: In commercial kitchens there are plastic containers holding large quantities of food or just open food items. These are a great source of food for rodents. It is important that these are well sealed and put in rodent proof containers.

3. Water/spills: Sanitation, not only within buildings but also around building perimeters, is vital in rodent control. If a rodent finds a feast in a greasy dumpster that is in close proximity to a building, it is likely that they will find their way into the building. Once inside, if the facility is not well sanitized and clean, a rodent is likely to find additional food sources. Water is also a sanitation concern as it provides one of the three basic needs for a rodent to be safe and secure inside a building. Any water leaks or standing water should be addressed immediately to avoid creating a welcoming environment for rodents.

4. Pest Control: In conjunction with the above tactics, pest control plays an important role in eliminating a rodent issue. Traps will often have to be set, and rodent stations may be necessary around the perimeter of the building. Be sure to call a professional before any problems arise or escalate.

Rodents have the potential to be at large this winter, so it is important that you do your part in helping them stay far away. While some rodents may look cute, they carry a number of economic and health risks. Eliminating rodents’ access to food, water, and shelter are key to preventing rodent issues this winter and year-round.