The FPA Blog

Exterior Population Considerations

Exterior Structural Design

Photo: While this landscape is appealing to the eye, this is creating increased pest pressure for this facility.

There is hardly any company that has not experienced the frustration of failing to get control of an insect population despite their efforts inside of the facility. The process of elimination often takes exhaustive efforts and many a blind path is taken. Many observing would have the impression we are chasing our tail in an effort to eliminated the activity.

Over the years, the frustration has led to the use of quantities of insecticides to rid a food plant or other structure of an insect issue. Frequent fogging applications, fumigations and repeated residual insecticide applications were conducted to rid the operation of the problem. Repeatedly, within a few weeks, the problem returned and in some cases at higher populations that previously encountered.

There are undoubtedly many contributing factors to why this happens. There can be failures in the applications, sanitation and structural issues that favor the insect population and their recovery as well as a constant import of insects from the supply chain being unchecked. Regardless of all of these, one area often not recognized is a population source from the exterior of the facility.

One issue we seem to have is that we tend to narrow our resources for information in the area we work in most of the time. When we specialize in structural pest control we have a tendency to limit our sight on the interior of the structure and a specific area where infestations appear to be. For the most part, this strategy can be successful and satisfy our customers but there are those cases where this just does not work.

A considerable amount of work has been done studying insect migration patterns and overwintering locations in the agricultural area. The focus has been on grain bin management and how to reduce the damage to grain being stored for long periods. In colder climates, questions were being raised about survival during the extreme cold and re-infestation of grain spring. The questions opened an entirely new look and the insect’s behavior as it related to its environment.

Research projects conducts by Dr. James Campbell and associates at the USDA research center in Manhattan, KS on the migration of Lesser Grain Beetles (Rhyzopertha dominica), opened the door to a better appreciation of these insect. The data collected indicated a high level of success is surviving cold climates in the surrounding environment and a migration to the new grain when placed in the storage bins. This provided one more important bit of information to develop changes in the approach to managing this insect.

This information opens the door to looking at several troublesome insects we encounter in the food plants. Is the same true for warehouse beetles, cigarette and red flour beetles? How about other insects such as psosids and fungus beetles? Time and evaluations of various infestations have clearly indicated this to be the case.

The things that these insects share as common traits is that they belong to groups of insects that survive outside of structures. We may become blinded to this fact because we encounter them in structures associates with a particular process. The other thing they share is their ability to be highly mobile either by flight or transfer on items moving in and out of plants.

The warehouse beetle belongs to the Family Dermestidae which contains the Species Trogoderma. Many of these insects are exterior species with a few having a fondness for living inside and feeding on grain based materials. These are extremely hardy insects and have been trapped in high numbers on the exterior of facilities in Michigan and other areas of extreme winter conditions. Since the structures in these areas provided overwintering locations for other insects such as cluster flies, Boxelder bugs and Asian beetles, the migration of the warehouse beetle into the structures to feed on these insects actually is a likely behavior pattern. Once in the facility, the adaptability of the insect allowed if to successfully establish itself as an interior infestation.

Cigarette beetles belong to a family of wood boring insects (Anobiidae) that in some parts of the more moderate climates can do very well living outside of facilities. When the opportunities present themselves either through poorly managed grounds or openings into structures, they will readily migrate in and establish populations. Areas such as Texas, Louisiana and other southern states frequently have high numbers of these insects on the exterior that go undetected and are constantly trying to gain entry.

Seldom so we think of the flour beetle being a problem outside of a facility. For the most part, you would be correct if you are thinking of Confused flour beetles. However, the Red flour beetle which meets the criteria for being highly mobile needs to be considered in some situations. It is frequently encountered on the exterior around nut processing facilities and others where foods are available on the exterior of the structure. Their flight capability and prevailing winds are often a perfect combination to deliver them the entry door or intake vent of a food plant.

As far as other insects (fungus feeding species) we seem to frequently encounter along the interior walls of food plants often are finding their way in from exterior sources. The insects gather in large numbers in the Insect Light traps installed in appropriate locations. Too often though, even after exhaustive investigations of internal sources we do not consider the exterior as the source. Often because some of the source may be beyond a distance we would consider as a source. Things to remember is that the area beneath the asphalt or concrete slabs around a plant will retain sufficient moisture to provide a breeding area for many of these species. Exiting through the expansion joints or cracks, they then migrate to the structure and gain entry.

There are many times where the efforts used inside of a facility can achieve acceptable control. Controlling the environment in a facility through proper sanitation practices conducted on a schedule times to the biology of the insects of concern are #1 in dealing with infestations. Maintaining the structure in a top-notch condition that minimizes arras where product can collect to provide a food source are also critical. However, when the infestations become persistent and are a constant challenge, there likely is another reason that needs to be considered.

Not every facility warrants an extensive exterior monitoring program. However, if your facility has a significant amount of product susceptible to infestation by the insects discussed here, it may well be worth investigation. Persistent reoccurring infestation issues would be another indication that the exterior should be evaluated for a source population. The only way to eliminate this area as a possibility would be to initiate trapping devices. 

The process for monitoring is not complicated or does it need to be extensive. In most cases, the installation of a few commercially available pheromone traps for the species you are investigating is all that is needed. Keep the devices out away from the facility rather than placing them near access doors or intake systems. Within a few days of placing the devices, you should have a good idea in you need to be concerned about exterior populations and their impact on internal populations.

The data collected is likely to open an entirely new emphasis on the condition of the structure and work needed. Some facilities found that extensive work was needed to modify the exterior of the facility to keep insects from easily entering once the population inside dropped sufficiently for them to enter. Often there is a balance established between the internal and external populations due to an availability of resources. Pest control efforts such as a fumigation can quickly crash a population and open an opportunity for significant migration of external populations Proper data collection and evaluation will provide valuable information on this issue occurring.

This is information brought to you by Al St.Cyr.  If you would like to learn more about Structural Design / Why Pests are at your facility, join us for our Sept & October 2017 Webinars or view their recordings here

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