Specialty Pest Management Inspecting Shelves in Commercial Food Facilities

Editor’s Note: This article was reprinted with permission from Pinto & Associates.

Poor shelving design is a main reason that shelved food products become infested with stored product pests. The standard shelving that holds raw ingredients and finished food products in warehouses and retail stores has a flaw. Warehouse shelving is engineered to be sturdy but its design also allows food to accumulate at the base of the shelving in an area called the "boot." Store shelving, called gondolas, often have a "kick plate" that hides a void at the bottom.

One way to determine if food insects are living in shelf boots is to use a flashlight to look for spiders or spider webbing. Old webbing will have an accumulation of dust on it while new webbing will have a clean, bright, thin appearance. New webbing means a spider is active in the area, which means it has a food source in the area, which often means that there are stored product pests nearby.

Cleaning shelf boots is not easy. The time is takes to go through a large warehouse and vacuum all the boots is considerable, even with a special attachment. One control method is to spray the boots with an approved insecticide. This is faster than cleaning but the residual effect of the pesticide lasts only so long.

Shelving in the "back rooms" of a retail store is often overlooked since it is not seen by the public. The back rooms are holding areas for products to be stocked on store shelves, or sometimes for damaged or dated products to be returned to the manufacturer. These areas don't receive the same level of cleaning as the front of the store. Products fall from shelves and may be kicked under the shelves where they can remain forever. The code dates on some products found under back room shelves have been seven years prior to the time they were discovered! Most sales floor infestations begin in the back room. When a food product is taken from the back room and placed on store shelves, it may already be infested with stored product pests, or it may become infested soon after.

The construction of retail store shelving and aisles give insect (and rodent) pests an advantage. The shelves are seldom removed to be cleaned or areas underneath swept. The accumulation of food debris and trash under shelving can be impressive. The pet food, bird food, grass seed, and cereal aisles are the worst. The small pieces that fall from the broken bags and boxes can fall through the holes in the shelves and accumulate beneath.

Because this area beneath the shelves is out of sight, store personnel are unaware (or choose to be) that this is happening until it is too late. Another area often overlooked is the area behind each bank of shelves. The void between two back-to-back gondolas can be 6 to 12 inches, and between gondola and refrigerated case as much as 2 to 3 feet. A whole lot of product can fall into these gaps over the years. Each gondola unit should be broken down occasionally and the area vacuumed.

In retail food stores, shelving may have an enclosed base or "kick plates," metal plates (false fronts) that cover the gap between the bottom shelf and the floor. All kinds of food debris falls from the shelves or is swept or mopped into this hidden space. Without access to this important void space, pest management is nearly impossible. Make sure you have the tools necessary to remove kick plates. In some cases, to inspect the area under the shelves, you will have to remove the items on the bottom shelf, then lift the shelf up and out. An organic or non-organic pesticide can be placed in this area. Diatomaceous earth (DE) is certified organic and works well to create a dry environment that prevents insects, and especially mold mites, from infesting this area under shelves.

Pet food is probably the most likely product to be infested in a food store, especially by Indian meal moths. Two changes in this area of the store can help manage stored product pests. (1) If you can get the store to agree, it's a good idea to remove shelves in the pet food aisle completely and replace them with bagged pet food on pallets. When a pallet is empty, it is removed and the area is swept clean before another pallet is moved in. (2) Peg board is often utilized in the pet food aisle for the display of small, high price items. This peg board is ideal for wandering Indian meal moth larvae looking for a place to pupate. The round holes are a perfect place to protect the defenseless pupa and also provide a perch from which to take its first flight as a moth. Eliminating peg board (at least in the pet food aisle) is an advisable step in a pest management program.

The authors are well-known industry consultants and co-owners of Pinto & Associates.