How To Put A Halt On Trojan Horses

In a large food plant recently, the warehouse received and signed off on a pallet of food ingredients. Unbeknownst to plant personnel, the pallet contained a nest of mice within one of the boxes. To the concern of the employees, when they moved and disturbed the pallet the next day, the mice emerged and ran in all directions, disappearing inside the plant.

As most of us know, this scenario and ones similar to it are not uncommon. Infested goods, supplies and equipment are admitted into our stores, warehouses, restaurants, schools, hospitals, homes and many other everyday accounts on a regular basis. I refer to these infested goods as “Trojan horses.” That is, we often allow infested items into buildings and operations. Over time, the pests “sneak out” of the supplies and hide within our buildings. These Trojan horse events can change the pest profile of an account from being pest-free to pest-infested overnight. What’s more, recipients of Trojan horses assume “ownership” of the pests once they have signed off on the delivery.

LOCATING TROJAN HORSES. Pest Trojan horses typically involve infestations of rodents or arthropods hidden inside boxes, bulk food, equipment or furniture. Certainly, live mice (and less frequently, rats) are perhaps the most serious concern as they can quickly disperse deep into facilities. But rodent carcasses and droppings within boxes, or on pallets, are also of concern as these contaminants can potentially find their way into production areas as the contaminated product is transferred.

Pallets themselves can also be Trojan horses. Pallets are frequently stored outside and on the ground until they are needed. Wood is a natural and attractive material for many insects and small mammals. Thus, wooden pallets sitting on the ground for days or weeks at a time are regularly invaded by pests.

I am constantly amazed how many commercial accounts that are otherwise pest-free and clean accept and sign off on deliveries placed upon filthy and dilapidated pallets, which are prime Trojan horse candidates. But even “clean” pallets may deliver pests into buildings. Carpenter ants and powder post beetles occasionally occur within pallets. Psocids, spiders and various other small arthropods are also routinely introduced within the crevices of wooden pallets.

Semi-trailer trucks can also serve as Trojan horses. Trailers used to transport food goods are usually kept clean and thus do not pose much of a Trojan horse threat. But food plants and warehouses routinely allow “cardboard/trash trailers” to dock directly to open shipping and receiving bays for prolonged periods. These trailers are often dirty and frequently contain pests or pest droppings within the trailer walls and floors. Pests living within these trailers docked at open bay doors can detect the warmth or food odors from the warehouse or food plant and invade.

Trojan horses are not only a concern for the food manufacturing and warehousing industry. Commercial accounts, such as restaurants, supermarkets, hospitals, hotels and schools receive hundreds to thousands of boxes of various supplies on a monthly basis, year-round. Yet, for the most part, these accounts usually do not inspect incoming deliveries. Cardboard boxes serve as one of the most universal German cockroach and pharaoh ant Trojan horses.

PREVENTING TROJAN HORSE EVENTS. No one can prevent Trojan horses completely. It is not very practical to inspect every box or item of the thousands that are delivered each year to commercial accounts. But as pest management professionals, we should educate our clients as to the possibility of Trojan horses, and thus the need for regular incoming inspection programs. Such programs will help to limit the frequency and severity of new infestations.

Additional suggestions:

1) Incoming product on trucks and railcars should be visually inspected prior to unloading, and again halfway through unloading for signs of pest activity.

2) Random inspections of the contents of boxes and goods (e.g., 10% of product) should be conducted periodically. The frequency of inspections might range from weekly to monthly or longer depending on the amount and diversity of material received.

3) For large commercial accounts, pallets can be selected randomly and visually inspected, as well as blacklighted for rodent urine and droppings.

4) For many food and pharmaceutical plants, it is a wise policy to notify vendors that deliveries will not be accepted if products are placed on dirty pallets and pallets will be inspected and rejected if they are not clean.

5) For grain processing facilities and warehouses, pheromone traps can be installed in receiving areas to provide an early warning of possible grain pest infestation within incoming materials.

6) Of course, infested incoming products should be rejected. But if the infestation is discovered after the delivery is accepted, the product should be isolated and contained (e.g., on a trailer). The vendors from whom Trojan horses were received should be notified and all future deliveries from these vendors should be carefully monitored.

7) Sometimes employees in restaurants and commercial kitchens panic when, upon opening a box of supplies, they discover it is infested with cockroaches or ants. Trying to spray or kill the pests in some fashion may cause the pests to quickly disperse. The best strategy is to carefully close the box and isolate the box from the area. Providing the box isn’t too large, it can be installed and sealed inside a black plastic bag. The bag can then be either placed into a freezer, or if it is during the summer, the bag can be placed out in the sun. After the insects are “frozen or fried” the supplies can be removed from the box.

Pest Trojan horses are something every commercial and residential account certainly wants to avoid. Still, when they do occur, these events serve as a salient reminder to the public and to our commercial clients as to the need of having pest management professionals nearby to quickly respond to these emergencies. In other words, we are Trojan horse insurance policies.

Dr. Robert Corrigan, a contributing editor to PCT magazine, is president of RMC Pest Management Consulting, 5114 Turner Road, Richmond IN 47374, 765/939-2829.