6 Signs of Rodent Infestations at Food Processing Facilities

Many parts of the United States are in for a blistery cold winter season this year, which brings new challenges for pest management in food processing facilities. One of the most notable challenges these facilities face is increased pressure from rodents who seek out food and shelter in extreme weather. These issues are amplified by erratic weather and extreme snow, to which many areas have become accustomed. A rodent infestation could shut down a food processing facility and lead to a loss of product and profit. Additionally, these pests can transmit diseases to employees.

Rodent infestations are extremely dangerous to the health and safety of employees who work in the facilities, as these pests can transmit Salmonella, which can also contaminate food manufactured in the facility. In fact, rodents are known to contaminate or consume about 20% of the world’s food supply.

To prevent infestations, it’s very important for facility managers and their employees to have some baseline knowledge of the different rodent species they could be facing. The most frequent invaders found in the U.S. are deer mice, house mice, Norway rats, and roof rats.

• House mice. These are the most commonly encountered rodent in the U.S. and, despite their name, they are the most common invader of commercial facilities. They usually nest in dark, secluded areas such as storage rooms and basements. These pests can cause serious property damage by chewing through drywall and wires, which can then spark electrical fires. House mice also pose a significant threat to food processing facilities, contaminating food products and spreading disease. House mice have been implicated in the spread of Salmonella through their feces.
• Deer mice. These mice typically live in rural, outdoor areas and are less common in urban areas; however, this does not reduce the risk they pose to food processing facilities located in more rural settings. They will often prepare their nests in old fence posts, tree hollows and log piles but will also seek shelter in commercial buildings, storage areas or vehicles. Deer mice present serious medical concerns as they can be carriers of hantavirus, a characteristically influenza-like illness which can be accompanied by kidney, blood, or respiratory ailments and is potentially fatal.
• Norway rats. Similar to house mice, Norway rats often nest in basements, in piles of debris, and in other undisturbed areas and materials. They especially like burrowing into soil underneath sidewalks, slabs, or low-growing shrubs. Norway rats have a propensity to gnaw through almost everything, including plastic and lead pipes, which can damage food processing machinery and spark dangerous electrical fires. Norway rats are also carriers of serious diseases including rat-bite fever, leptospirosis, trichinosis, and salmonellosis.
• Roof rats. Named for their tendency to find shelter in the upper parts of buildings, roof rats not only damage materials by gnawing through them, but they also contaminate stored food and serve as vectors of dangerous diseases. Roof rats are willing to eat practically anything available to them; however, their preference to feed on seeds, nuts, fruits, and berries which may draw them to food processing facilities. Roof rats secured their place in history by spreading the highly dangerous bubonic plague. Though transmission is rare today, there are still a handful of cases in the U.S. each year.

Signs of an Infestation

To keep their facilities safe, food processing facility managers need to regularly inspect the building and machinery for signs of an infestation. Here are the top signs of a rodent infestation facility managers should keep an eye out for:

• Droppings: Mouse or rat droppings found around the facility are some of the most common signs of rodent infestation. These pellets are often left behind in places where food is stored, as well as under sinks, inside chewed cardboard boxes, along baseboards, and on top of wall beams.
• Gnaw marks: Rodents can cause serious property damage by chewing through almost any type of material—including plastic and lead pipes—to obtain food or water. House mice and Norway rats are also known to gnaw on wires behind walls, sometimes causing fires.
• Nests: Rodents prefer to nest in dark, secluded areas where there is little chance of disturbance. House mice, specifically, like to build their nests out of shredded paper products, cotton, packing materials, wall insulation, and fabrics. If facility managers find these materials scattered around guest rooms or common areas, it might be a sign that rodents are nearby. Norway rats typically nest in underground burrows, often near building foundations, while roof rats may nest in ceilings or attics.
• Tracks or rub marks: Rats tend to leave dark grease or dirt marks along walls and floorboards as they follow a trail through the building between their nest and food sources. Facility managers should keep an eye out for these rub marks, which are caused by the rat’s oily fur.
• Strange noises: Getting complaints that employees are hearing strange noises in the walls? Chances are these sounds can be attributed to rodents scurrying about the facility, between the walls and up in attics. Rodents are especially fond of storage spaces because they prefer dark, secluded spots.
• An actual rodent: Mice can breed rapidly, so if a facility manager or a customer spot one mouse in the building, it’s likely there are others playing hide and seek. In fact, a female house mouse can give birth to a half dozen babies every three weeks, producing up to 35 young per year.

Rodent Prevention

Food processing facilities are likely required to work with a licensed pest control company for ongoing pest inspections, routine maintenance visits, and treatments as needed. Working with a qualified pest control company is essential to ensuring your food processing facility remains pest-free. Your pest control partner will work with you to implement an integrated pest management (IPM) plan. An IPM plan is a comprehensive pest control method that that focuses on three basic techniques: inspection, identification, and treatment by a pest control professional. This method will help to ensure that pests are properly controlled and deterred as well as to ensure that your facility is clean and compliant.

In addition to working regularly with your pest control partner, facility managers should implement these prevention tips to avoid unwanted rodent run-ins:

• Trim back trees and foliage close to the foundation;
• Seal any cracks or holes on the outside of the building;
• Repair any broken vent covers, loose siding, or shingles;
• Keep storage areas clean and organized to eliminate any potential nesting grounds;
• Properly ventilate storage areas and machinery to prevent moisture buildup that can attract pests;
• Keep food products sealed and stored properly in air-tight containers;
• Clean high-volume areas often, including employee break rooms, bathrooms, and lobby areas where crumbs and trash accumulate daily; and
• Dispose of garbage regularly and store in sealed receptacles placed at a distance from building entrances.

Rodents will be a continued threat to food processing facilities, but facility managers can ensure they’re prepared through proper education, prevention, and—most importantly—a partnership with a reliable pest control professional.