Whether or not you see the evidence of a rodent infestation, don’t assume that they aren’t present. “Rodents are an on-going challenge for every swine producer and feed mill manager in the business,” according to Mike Stringham, North Carolina State University Extension entomologist.

With effective, ongoing rodent-control management, you can actually eliminate rats from a facility and control mouse infestations, he says. But you must keep up the vigil.

Effective rodent management requires monitoring, sanitation, exclusion efforts and the appropriate control for the specific rodent. 

It all starts with monitoring, which requires regular checks. Remind managers and workers to look for rodent activity while on their rounds. Inspect a dozen random locations through a facility once a month, and use a bright flashlight for the darker areas.

Look for gnawing damage or tracks in the dust. Check closely for droppings. Look for bits of debris such as insulation on the floor or beneath slats. Look for evidence of rodent activity such as holes or burrows in loose insulation, especially along water lines. Don’t forget to examine overhead spaces and eave vents, Stringham says.

With fall weather approaching, rodents will be more aggressive about moving inside. Walk the building perimeter and look for potential entries such as holes in damaged siding, and gaps around pipes, conduits and feed lines where they go through the wall. Close any gaps around fan housings. Keep all entries in good condition with tight fits.

Keep a bare, gravel or mowed perimeter around all facilities. Remove feed spills immediately. Keep the storage rooms clear of debris. 

The most effective rodenticides are brodifacoum, difethialone, bromadiolone, cholecalciferol, bromethalin and zinc phosphide, he points out. The last two are best suited for the rapid reduction of severe infestations. “But always read and observe label directions first,” Stringham adds.

Bait stations placed along the inside and outside walls of the hog building can help intercept rodents where they enter. Bait stations spaced at a minimum of 40 feet apart provide plenty of opportunity for rats to find baits. Mouse control may require shorter spacing. Don’t neglect storage rooms, labs, locker rooms and break rooms, he says.

Also, don’t forget about roof rats.Block baits can be nailed to rafters that both roof rats and mice patrol. They can be wired in place along water lines or conduits. Attach block baits as close as possible to rodent entry points from attic or wall voids. 

Several strategically spaced bait stations in attic spaces are an effective approach to control roof rats. “However, success requires that each station must be easily accessible so that rodenticide-laced water and pellets or blocks can be replenished as needed,” Stringham says.

Norway rats are more easily controlled. Well-placed bait stations at the building’s perimeter and interior will intercept many, but not all. Place bait outside the burrows to make Norway rat control complete. “A couple consecutive days of baiting each active burrow with a single-dose rodenticide is often sufficient to eliminate the problem,” he says. “If rodents remain, baiting may be required for several more days.”

While you may think of fall and winter as the time to step up rodent control, you know they don’t watch the calendar and once they set up house, they stick around.