[Tech Talk] Surprising Food Plant Pests

Columns - Technically Speaking

The novelty factor of food plant service is what makes this type of work challenging and interesting. The diverse environmental conditions, variety of incoming materials (including global imports) and facility locations can all add to the uniqueness of pest problems.

November 21, 2011
Pat Hottel

Although the name of this article is "Surprising Food Plant Pests," there shouldn't be any real surprises when an "odd" pest shows up in a food plant. Food plant service pest professionals quickly learn to expect the unexpected. The novelty factor of food plant service is what makes this type of work challenging and interesting. The diverse environmental conditions, variety of incoming materials (including global imports) and facility locations can all add to the uniqueness of pest problems.

Diverse Environments. Food plants may include wet processing areas, dry processing areas or a combination of both in one site. Wet processing areas, as the name implies, involve a lot of water or liquids as part of the processing and clean-up. There also can be high temperatures involved as part of the process. Multiple micro-habitats of varying moisture and temperature ranges can be present in an area. Bottling and canning plants are examples of wet processing facilities.

Dry processing areas are facilities where grains and other solids are processed and made into food products. Flour mills and grain processing plants are considered dry processing facilities. Dry processing areas of plants typically support traditional stored product pests like flour beetles, Indian meal moths and cigarette beetles.

On the other hand, wet processing areas are more likely to support ideal habitats for some unique pests. In wet processing areas, the "usual suspects" are German cockroaches, American cockroaches, small fruit flies, springtails and other moisture-loving pests. Some examples of the more unusual pests found due to high moisture include the Cuban cockroach, ants of the genus Hypoponera, lesser earwig and rove beetles.

I observed rove beetles on the inside of food plants on several occasions. In most situations, they are accidental invaders attracted to lights on buildings. But they have been tied to moisture leaks and sub-slab moisture conditions. Rove beetles are typically predaceous on other insects but some are mold-feeders. A pest that can be mistaken for rove beetles but is easily separated by the forceps on the end of the abdomen is the earwig. I recently visited a food plant where lesser earwig populations were residing underneath the slab and coming up through cracks around columns. This earwig is normally associated with decaying vegetation and manure but has been reported as a pest of food plants. It's much smaller than common structural earwigs. It was found in insect light traps in this particular facility and had been an ongoing issue in the building for years.

Cuban cockroaches are typically found outdoors. However, Copesan partner McCall Service discovered a Cuban cockroach infestation in a food plant in the southeastern United States. Moisture leaking onto insulation supported the ideal conditions for this pest to live and breed indoors.

Hypoponera ants have been an issue in several food plants and are often associated with sub-slab problems with phorid flies. It is suspected these ants are predaceous on phorid flies breeding in moist organic materials under the slab. Most often the plant has had a sub-slab pipe break (e.g., sewer pipe).

Incoming Goods and Materials. During a typical week, a food plant might receive millions of pounds of food ingredients and other materials. These incoming shipments may come from other regions of the country or from across the globe. A plant may receive anything from wood-destroying organisms on pallets, a pest in a raw agricultural food commodity or a post-harvest pest of food products. Some of the more unusual pests reported include Asian long-horned borer beetles in food warehouses and auger beetles on pallets. As the number and variety of imports increases, the potential for the unusual increases. Recent media reports indicate that government interceptions of quarantine pests like Khapra beetles at the ports have risen dramatically this year.

In addition to ingredients and other materials coming into the facility, employees can bring pests into the facility. The German cockroach is the most commonly introduced pest via employees. However, in recent years, employees have brought bed bugs into food plants.

Locations. The location of the plant can impact the types of pests that may enter the site, whether it is in an urban, suburban or rural area. The food plant pest provider needs to be aware of bordering resource sites for pests. Of particular concern can be neighbors with a high potential for pest breeding like farms, heavily forested areas, bodies of water, vacant buildings and landfills. Some unusual food plant pests found by Copesan partner companies have included:

  • Red tailed hawks
  • Pennsylvania wood roaches in roof
  • Fungus gnats in roof
  • Turkestan cockroaches
  • Harlequin cockroaches
  • Raccoons, opossums and bats
  • Black fungus beetles
  • Asian cockroaches (in Illinois on a trailer)
  • Springtails
  • Feral cats

When inspecting food plants, keep the possibility of an unusual pest in mind. Having a keen eye and open mind can help you identify pests in uncommon situations, and address conducive conditions. Remember to consider the environmental conditions, types of incoming materials and facility location when servicing these facilities.


Pat Hottel, a member of the Copesan Technical Committee, has almost 40 years of experience in the pest management industry. She's been with McCloud Services in Hoffman Estates, Ill., since 1980 and serves as technical director. Hottel holds a bachelor's degree in entomology from the University of Georgia and is a BCE. She was one of the first women in the industry to hold a technical director position when she worked for Bermuda Pest Control in 1976.

Copesan is an alliance of pest management companies with locations throughout North America. To learn more, visit www.copesan.com.