Exterior Rodent Management at Food Plants: A Risk-Based Approach

Why would a mouse or rat be attracted to a food plant? Perhaps it is odors emanating from open vents and doors? Maybe it is warm air produced by the cooking process, or there are harborage zones, such as low-growing shrubs, along a building’s perimeter?

Conditions vary on each side of a food plant. For example, dock doors and dumpster areas are more conducive to rodent entry and development than a concrete wall with limited entry points. Despite such differences, many food plants have rodent stations spaced evenly around all walls. What does this truly accomplish? Furthermore, how much time do boilerplate rodent management programs waste that could be utilized for proactive rodent inspections?

Unfortunately, the “why” of rodent equipment spacing is often dictated by auditing standards. Many third-party auditors require stations and equipment placed in different ways, but what they ask for is not particularly science-driven. It is more of a “let’s have a station every ‘X’ number of feet, so if a rodent randomly gets to the building it may encounter a control device.” This strategy implies rodent activity is more or less random, and not predictable.

RETHINKING PLACEMENT. In actuality, rodent management devices should be placed along food-plant perimeters based on rodent-activity data collected through visual inspections, device-maintenance services, and trend-analysis reports. This helps reduce rodenticide use, places stations where they are more effective and frees up time for the most critical part of pest prevention — Inspection.

Exterior areas of food plants typically have some level of rodent pressure. Analysis of the habitat profile on the food plant’s property and adjacent properties is key. For instance, areas with field crops or meadows are more prone to rodent populations than paved sides or parking lots. Docks and dumpsters are particularly vulnerable to rodent activity. Detailed analyses and assessments of food-plant properties provides a road map for selection, use, and placement of rodent control devices.

In addition, ongoing, proactive analysis of exterior rodent pressure through data collection is the cornerstone for deciding numbers of exterior devices needed and where they should be placed. Data-collection software platforms can expedite the data collection and analysis process through trend reports that provide valuable insights into where and when rodents are encountering the exterior areas of the food plant. However, in order for the rodent data inputs to be accurate and concise, one must remember the old saying, “Junk in equals junk out.”

SEEK THE MASSES. Rodent populations, like most other pest populations, tend to be clumped and not evenly distributed around exterior building perimeters. Doesn’t it make better sense to place exterior rodent control devices where these rodent populations “clump” for maximum effectiveness?

Exterior, tamper-resistant bait stations with rodenticide baits have been the gold standard of rodent management at food plants for decades. However, rodenticides are not necessarily the only materials that can be used inside tamper-resistant bait stations. Non-toxic monitoring blocks (Detex, NoTox) can also be used at food manufacturing facilities. Non-toxic monitoring blocks reduce non-target organism poisonings, as well as rodenticide cost and waste. Just think of the tons of rodenticide waste that could be put to better use than at the bottom of a landfill.

When non-toxic monitoring blocks are used at food plants, bait stations that exhibit rodent activity or captures must be serviced weekly until the rodent activity ceases. Some pest management companies simply place rodenticides in lieu of the non-toxic monitoring block until the rodent activity ceases; some install snap traps to catch the foraging rodent; others utilize snap traps that immediately stop the rodent activity, contain it within the station, and help identify the exact species of rodent that is feeding within the station (e.g., white-footed mouse vs. house mouse). Some companies abandon monitoring blocks altogether and use snap traps 100% of the time.

If a snap-trap strategy is employed, it is critically important that pest professionals servicing the stations be able to accurately identify and interpret rodent signs such as fecal pellets, sebum stains, and gnaw marks, and to install proper snap-trap types (e.g., rats vs. mice) inside each station.

Snap traps used inside exterior bait stations are likely to also be investigated by insects, especially ants. Insect baits can be used inside and around bait stations, according to label directions, to help reduce insect activity. The Nara Lure is a relatively new novel device that also can be used as a snap trap attractant (plastic matrix with an allergen-free, aromatic attractant) which could reduce insect contamination.

Bait-station types play a big role as well. The lock-and-load style stations or patio stone-based anchoring system that permits easy relocation are best suited for risk-based rodent management. These types of baitstations can be shifted to areas with higher rodent activity with minimal lost time for the pest professional and can be cleaned much better than unmovable bait stations. But each time bait stations are relocated, the equipment map for the food plant also must be updated to reflect changes.

Multi-catch traps also can be used outside. Powder-coated traps can withstand most weather conditions and, when used properly, can reduce interior mouse captures. At one food plant, seasonal rodent capture rates fell a whopping 90% because of exterior multiple-catch traps.

THINK AND ACT PROACTIVELY. In summary, exterior rodent management programs need to make sense and match the exterior ecology of each food plant. Cookie-cutter rodent management layouts waste time and resources because the majority of exterior bait stations or equipment will never kill or capture rodents. It’s much better to divert the labor used to check unused equipment into proactive inspections and data analysis and interpretation, and then place rodent control equipment where it will truly manage rodents. Remember, think like a pest to manage them!

Brian Beidle is technical services manager at Collins Pest Management, Evansville, Ind., and can be contacted at bbeidle@gie.net.

Article is reprinted with permission from PCT magazine, August 2015.