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Storage-free inspection aisles and sanitation lines are important “non-chemical” strategies for minimizing rodent (and other pest) problems inside food plants and warehouses. From a scientific perspective, there are several reasons for this including:

1 Direct Connection to Exterior Areas. When supplies are stored directly on the inside perimeter walls, without any inspection aisle, this situation becomes highly conducive to pest problems. Such walls are often connected to the immediate building exterior via utility lines entering through the walls or from the various wall and floor expansion joints and seams. Many times, these structural spaces and lines are not properly sealed or the seals separate over time, providing ample space for pests to gain entry. Mice require only about 6 mm to gain entry, while rats need about 12 mm. (For many insect pests [e.g. ants, grain beetles] entry space is measured by just one to two millimeters.)

2 Harborage-Seeking Behavior. Mice and rats are “thigmophilic” and phototropic-negative animals. These fancy terms basically mean “touch-loving” and “light avoiding.” Once rodents gain entry inside buildings, they gravitate toward dark and shadowy areas as created by supplies stored directly next to walls or where cracks and crevices formed by wall/floor junctions provide them harborage. Such areas help rodents avoid their predators.

3 Decreased Airflow is Attractive to Pests. Many insects and rodents prefer areas of low airflow. Insects lose body moisture rapidly when exposed to constant air currents passing over them. Rodents may lose precious body heat in these environments as well. Areas congested with supplies have low airflow and are therefore attractive to pests.

4 Food Spillage Remains Unnoticed. Because wall and corner areas are often where products get squeezed into available spaces, product breakage and food spillage are common. Eventually these areas become “out-of-sight/out-of-mind,” and they remain cluttered and uncleaned for prolonged periods. Rodents living or hiding in such areas discover that food can be consumed in the total protection of the clutter and darkness. When mice are present in these situations, they have an abundance of nooks and crannies among the cluttered boxes and pallets in which to explore and hide. As a result, the need is lessened for the mice to explore new holes (i.e. curiosity traps) in “uncluttered” areas.

5 Pest Control Efforts Are Hampered. Certainly, when inspection aisles and access spaces are not maintained, pest management efforts are hampered or even totally wasted. These spaces inside our buildings that are so vulnerable to rodents and other pests cannot receive proper inspection or the possible installation of rodent traps and monitoring stations (or any other pesticide treatments needed to control pests). Or, once rodent control equipment has been installed, the equipment cannot be serviced properly.

6 Structural Damage. Finally, when an inspection aisle program is not established or respected, walls are repeatedly damaged from stored products and supplies being constantly shoved into them or heavy loads falling onto them. Holes, depressions, and the many resulting cracks and crevices create ideal rodent and insect pest harborages.

Dr. Robert Corrigan is author of Rodent Control: A Practical Guide for Pest Management Professionals. To order a copy of this reference book, visit www.pctonline.com/store.