Rethinking Rodent Control: A Roof Rat Reality Check
As rodent pressure continues to evolve across the West Coast, so must the approach to control and prevention.
Sprague Entomologist Dan Scott, BCE, says one trend is especially concerning: the expansion of the roof rat’s (Rattus rattus) range.
“We’re seeing roof rats spread beyond the traditional Interstate-5 corridor,” says Scott. “They’re moving inland and north into new territory where property and facility managers haven’t historically had to think about them. That means it’s time to rethink our inspection habits and prevention strategies.”
Roof rats don’t play by the ground rules that other rodents follow. They are agile, aerial, and opportunistic preferring to travel and live in elevated spaces like trees, rafters, overhead pipes, and drop ceilings.
As a result, Scott notes, rodent management needs to be a 360-degree plan in commercial properties.
“If you’re only looking down or at eye level for activity or damage, you’re missing a whole world of risk above your head.”
The Challenge
When a long-time Sprague client – a large food processor – began receiving complaints from a major grocery retailer about rodent droppings inside the center of shrink-wrapped pallets of applesauce and fruit cups, the culprit wasn’t obvious.
Forklift drivers on both ends of the supply chain reported no signs of gnawing or torn shrink wrap on the pallets, leaving the source of damage a complete mystery.
Sprague’s Quality Assurance and Technical teams mobilized immediately, inspecting the 500,000-square-foot facility; one that had never logged a single rat capture in more than three decades of operation. Hundreds of snap traps were strategically installed, and non-toxic tracking powder was used around rack legs and posts to pinpoint potential rodent activity. Yet, the team found nothing.
When a second customer reported similar findings, the urgency grew. These “ghost” rodents were damaging product but leaving no trace of how they entered the pallets.
Solutions and Results
Based on the droppings and feeding patterns, Sprague’s experts identified the likely suspect: a roof rat. That insight prompted a shift in perspective – literally. The team began looking up.
They purchased motion-activated trail cameras and mounted them high atop the pallet racks to monitor what was happening in the shadows above the warehouse floor.
On the very first night, the cameras captured clear footage of a roof rat. The rodent had entered the building through a narrow gap – less than an inch wide – around a roof support post near a storm drain. Once inside, it climbed onto unwrapped pallets, slipped through the rounded corners of the packaging, and burrowed deep inside to feed, leaving no visible exterior damage.
With visual confirmation, the team installed snap traps on the upper racks near the camera site. The next night, the intruder was captured. The Sprague team then sealed the roof opening to prevent future access, and the facility has remained rodent-free since.
Lessons Learned
Roof rats remind us that pest threats aren’t always where we expect them to be. In this case, the solution required aerial thinking, creative problem-solving, and the strategic use of technology to uncover what traditional ground-level inspections missed.
Sprague’s approach reinforced a critical lesson for property and facility managers:
Never assume the rodent threat is at ground level. True prevention requires looking at your facility from every angle – inside, outside, and overhead.
Seeing What’s Hidden: The Growing Role of Cameras in Rodent Control
Technology is playing an increasingly important role in how pest management professionals monitor and manage rodents especially in complex commercial environments. Sprague’s Technical team has ramped up its use of cameras to identify rodent behavior patterns that traditional inspections can miss.
“Cameras are becoming a vital tool for large facilities like warehouses and processing plants,” says Scott. “They give us eyes in places that are difficult or impossible to access such as drop ceilings, overhead beams, and wall voids, and provide valuable insight into rodent movement.”
By capturing video footage over several days or weeks, Sprague Route Managers can identify alpha males, track travel routes, and pinpoint harborage areas inside and around structures. This data helps determine the most strategic placement of traps and bait stations, and where exclusion efforts are needed, improving both speed and effectiveness of control.
Cameras not only help confirm the presence of rodents, but they also eliminate guesswork and provide data that allows Sprague and their clients to maintain cleaner, safer, and more rodent-resilient facilities.
Where Roof Rats Hide
Since roof rats can spend their entire lives above ground, inspections must include elevated and concealed spaces such as:
- Exposed beams and pipes
- Hidden pipe chases and utility lines
- Wall voids and drop ceilings
- Concrete cinder blocks
- Top of shelving units and storage racks
- Overhead junction boxes
- On or inside large equipment (including ovens and mixers)
- Raised or false floors
With roof rats expanding their range, Sprague continues to lead with science-driven strategies, proactive inspections, and the mindset that effective pest management requires looking up, down, and all around.