Exclusion: The Best Rodent Prevention Tactic

A truck backs into the bay and the loading dock doors roll up, exposing roughly 9-by-8 feet of wide open “welcome mat” if you’re a rodent.

From deliveries to employee locker rooms and trash receptacles, there are many ways rodents are introduced into the food processing environment. Then, you have structural invitations: cracks, crevices, coolant and utility lines, mazes of old piping — anyplace where they can hide, feed and survive.

Let’s face it. Your plant is not like a bank vault.

“Food facilities are often 24-hour operations and move at alarming rates,” said William Hoffman, president and CEO of Hoffman’s Exterminating Co. in Mantua, N.J. “You can’t stop the wheels of motion or product to see if someone shut a door or find out where the truck that backed in was yesterday. Maybe parked next to a dumpster, and now that truck is backing into your facility and you’re opening your doors.”

Exclusion is a critical aspect of rodent control and pest control in general. The entry points rodents can manipulate to access a facility are considerable. When asked where rats have been seen on site, respondents to QA magazine’s annual State of the Rodent Control Market survey pointed to interior and exterior trash cans, dock areas, incoming goods, processing areas, in and around employee lockers, breakrooms and kitchens. Every respondent reported more than one “hot spot.”

“Exclusion is the foundation,” said Emory Matts, B.C.E., North American rodent technical manager at Rentokil, Carrollton, Texas. He has used thermal cameras to identify hard-to-find holes and gaps, especially on rooftops. “We’ll open up walls, drill a little hole and use an endoscopic camera to see what’s inside.”

Eighty-three percent of respondents said preventive measures include sealing cracks and gaps, and 66% install door sweeps or air doors. Other exclusion methods (41%) include dock levelers and fabric fill.

“The key is to make sure it’s a long-lasting fix,” Matts said. For instance, sand might be an easy way to fill a hole, “but rodents are burrowing animals, so they tunnel through it.” Pea gravel is more difficult for rodents to work through and can be used to hold sand in place.

While expanding foam is a go-to for exclusion, it’s not always the best solution. “Studies show that it has fractal bubbles, so it can hold viral spores and particles that can become airborne over time as the foam degrades,” Matts explained. “So, having that foam blocked off is a good idea, especially if you’re concerned about allergens or foodborne illness.” He suggests steel wool mesh, stainless steel or a sealant to cover expanding foam.

“We actually do not prefer a big, bright light shining over an entrance door, because when it’s attached to the building, you’ll get bugs that are attracted to the light — and when you have bugs, you have a food source for rodents,” said Matts.

A better illuminating strategy is to position the fixture away from the building and shine light onto the facility. Yellowish, pink and orange lights are less attractive to insects than bright-white or bluish lights.

In a perfect world, a facility is built to keep pests out, said Shannon Sked, Ph.D., B.C.E., director of fumigation at Western Fumigation in Parsippany, N.J. “No architect or engineer is thinking about that part, but a pest control professional always is, so including pest control partners in building design is really important,” he said.

The same is true when carrying out building renovations and addressing exclusion controls. “Have the QA specialist be part of the budgeting process so these ideas are considered,” Sked suggested. “If that person is in the room during budget planning, they can say, ‘We’ve had this pest problem. Maybe this year we should put some capital money aside to get the roll doors updated so they seal correctly.’”

Ultimately, exclusion is the best pest prevention tactic.

As Hoffman said, “We realized a long time ago that keeping critters out is a better control than waiting for them to come in and then kicking them out.”