Pest Trends in 2019

They may not seem like the trendiest of creatures but pests continue to evolve as their behavior and reproduction patterns change, and new invasive species emerge. What pest trends can food manufacturers and commercial facilities expect to see in 2019?
Sprague’s resident technical experts, Jeff Weier and Ashley Roden, peered into their entomological crystal ball and identified increased pest pressure from roof rats, the spread of brown marmorated stink bugs and Turkestan cockroaches, and possible behavioral resistance in rodents.

Roof Rats

“We are seeing the spread of roof rats to areas they have not historically occurred before,” says Weier. “This will cause challenges for clients.”
Roof rat population has grown in recent years up and down the West Coast, and they have done so unnoticed by most QA and property managers. They remain hidden in high, out of the way locations within a structure, and, unlike the more visible Norway rat, a roof rat may never touch the ground its entire life.
Roof rats are excellent climbers and can access and fit into more places within a facility.  They are more neophobic than Norway rats and will avoid any ‘new’ items including bait stations and snap traps. They are opportunistic eaters and will consume seeds, nuts, fruits, berries, insects, seafood and pet food.
Common roof rat nesting areas inside a structure include:
  • Hidden pipe chases and utility lines
  • Wall voids and drop ceilings
  • Concrete cinder blocks
  • On top of shelving units
  • Overhead electrical junction boxes
  • On top of or inside equipment (they have been found inside large ovens in commercial bakeries)
  • Raised and false floors 

On the exterior of a structure, roof rats can establish nests in the dead fronds of unmanaged palm trees, on fence ledges behind thick overgrown vines and vegetation, within dense overgrown trees and vegetation, and in wood piles, lumber stacks or shipping pallets stacked outside loading docks.
Their preferences, or the lack thereof for living accommodations makes roof rats difficult to manage. Roden recommends inspections and treatments done using lifts and ladders. These  are more time and labor intensive.

Behavioral Resistance in Rodents  

Weier and Roden also see the spread of ‘behavioral resistance’ in rodents. Data collected from monitoring and control devices revealed groups and populations of rodents not interacting with the devices (i.e. bait stations, traps, etc.) any more.
What is behind this trend? Roden blames control devices that have been installed and forgotten by the pest management service provider. This has led to the capture of curious, aggressively foraging rodents but left timid ones to reproduce, and allow colony populations to grow unchecked. 

Brown Marmorated Stink Bugs and Turkestan Cockroaches

Sprague has also trended progress of invasive pests such as the brown marmorated stink bugs and Turkestan cockroaches into the western States. It is likely both were introduced to the geographic region stowed in product shipments and bulk freight containers. 
The stink bug is a nuisance to commercial facilities (it can be a significant pest for farmers too) since they gather in large numbers and their presence, while not threatening to people or food, can alarm tenants, guests and employees.
Why are they called stink bugs? Because they release a chemical alerting their brethren to an area they’ve settled in and secrete a bad-smelling, bad-tasting fluid when disturbed or crushed. 
Stink bugs overwinter inside a facility and ‘wake up’ on unseasonably warm winter days streaming out of wall voids or drop ceilings. They typically gather near windows, lights, TVs or computer monitors that radiate light and warmth.
The key to preventing a problem with stink bugs is to exclude them from your facility in the first place. Follow these maintenance procedures to block stink bugs:
  • Seal cracks around windows, doors, electrical outlets, ceiling fans and light switches. Pay close attention to areas including around siding and utility pipes, underneath the wood fascia or other openings. 
  • Keep branches and shrubbery well-trimmed so they do not come in contact with the roof. 
  • Replace exterior lighting with yellow bulbs, which are less attractive to stink bugs.
  • If you do find stink bugs inside your facility, use a vacuum to accumulate them, empty the contents in to a plastic bag and dispose it immediately. 

First introduced in late 1970s on an Army base in California, Turkestan cockroaches were considered an exterior pest that did best in warmer climates. Sprague has seen a recent uptick in reports from clients in Oregon and Washington experiencing issues with Turkestan cockroaches.
“We have discovered they can withstand colder temperatures than was previously thought and we are seeing them survive inside large commercial coolers,” says Roden.
What makes Turkestan a challenge to manage is their ability to breed rapidly and in large numbers. Following good sanitation protocols and sealing entry points into a structure are two important steps to effective control.

Where Do Turkestan Cockroaches Live?

On the exterior:

  • Utility (water and electrical) meter boxes
  • Stored pallets
  • Center block walls
  • Compost piles and landscape litter
  • Potted plants
  • Sewer systems

On the interior:

  • Coolers in bar and food storage areas
  • Behind baseboards and door frames
  • Wall voids
  • Around hot water tanks and sinks
  • Floor drains
  • Drop ceilings
Commercial Properties