Food Safety and Insects

Stephanie Richards, PhD, Medical Entomologist

What are the primary pests in food processing?

Pests such as flies, cockroaches and rodents are considered pests of food processing and storage areas. Some beetles and moths are also pests of stored products. Pests can be more difficult to control if not monitored and targeted at the beginning of the infestation, hence integrated pest management principles should be followed to prevent economic losses and public health issues.

What are the types of food facilities to which pests are attracted?

Facilities that store dry products (e.g., flour, rice, candy, animal feed) may have pests (e.g., beetles) that do not need large amounts of water. Where wet products (e.g., dairies, wineries) are stored, pests such as cockroaches and flies are more prevalent. Food retail settings (e.g., grocery stores, restaurants) may experience a wider variety of pests, such as cockroaches, flies, ants and rodents. Food contamination can take place at any stage in the food processing and distribution cycle, and pest management professionals can help protect the health of the consumer at every stage.

What is mechanical transmission?

Mechanical transmission can occur when a pathogen (e.g., bacteria) is incidentally carried on the body (e.g., legs) of an insect, such as a fly or cockroach. When the insect lands on exposed food or a food preparation surface, the bacteria may be transferred to food. When uncooked or improperly cooked food is ingested by humans, gastrointestinal issues may occur.

Can flies and cockroaches make me sick?

Flies (e.g., house flies, filth flies) and cockroaches (e.g., American cockroach, German cockroach) can mechanically transmit bacteria such as Salmonella, Staphylococcus aureus, Escherichia coli and Listeria that can cause food-borne illnesses. These types of illnesses can result in diarrhea, gastrointestinal pain, cramping and fever.

House flies and filth flies lay eggs and develop in areas such as manure, garbage, animal bedding and decaying animal matter, hence their bodies may be covered with bacteria. They also regurgitate their food and defecate on surfaces, and this provides an additional means for bacteria transfer to food and food preparation surfaces.

Flies can be controlled by removing their food and larval development sources (e.g., manure, decaying plant/animal material, trash). Window and door screens can help exclude flies from indoor areas. Restaurants and other facilities may consider using a double door entry and/or air curtain system (i.e., fans that blow air out as customers enter) to minimize flies entering buildings. Insect light traps can also be used to attract (e.g. ultra violet light) and kill (e.g. glue board) flies. Residual insecticides are sometimes applied to outdoor surfaces where flies rest (e.g., barns, restaurants), and this can suppress fly populations.

Cockroaches lurk in cracks and crevices in dark, warm areas and they are primarily active and forage for food at night. In areas of high cockroach infestation, a buildup of fecal matter and cast exoskeletons will be present.

Sticky traps can be used to monitor cockroach populations before and after treatments. The use of a vacuum can be an effective method for removing accessible cockroaches and related debris. Subsequent sealing of entry points/hiding places and removing food and water sources from the indoor environment are important components to an integrated control approach. Clutter should be removed to prevent harborage of pests. Baits, other types of insecticides and dusts applied in cockroach habitats can also be effective means of control. In some cases, insect growth regulators are used for longer periods of control.

Are beetles and moths a threat?

In stored food facilities, moth and beetle infestations may become an issue due to food damage and buildup of cast exoskeletons and other body parts. This can indicate unsanitary conditions involved in food storage. Common treatment is disposing of the infested product and sanitizing the area. In some cases, fumigation may be required.

Do ants pose a health risk?

While ants do not necessarily transmit pathogens, they are considered a pest and are a major nuisance in food facilities. Treatment options depend on the ant species that is present as ant biology and habits vary by species. As with other pests, appropriate cleanup of waste will minimize the occurrence of ants.

What about rodents?

Rats and mice are a problem for food storage and processing facilities. Their excrement can contain harmful bacteria that can contaminate food products. They can also cause physical harm to structures via chewing through walls, packaging and even wiring. Garbage disposal areas must be kept separate from food storage and preparation areas and should be maintained properly. Potential cluttered harborage/nesting areas should be removed. An integrated management approach using cleanup, exclusion, bait stations and traps that are frequently monitored can help control a rodent issue.

Surveillance and targeted control of pests such as house flies, cockroaches and rodents are of great importance, especially in food production and preparation facilities. The recent regulations from the Food and Drug Administration’s Food Safety Modernization Act seek to prevent contamination, thereby reducing food-borne illnesses. Suppression of and/or prevention of pest issues is generally more economical than responding to a high degree of infestation. In any case, trained pest control technicians should be contracted to carry out integrated pest management.


Dr. Stephanie L. Richards is an Associate Professor of Health Education and Promotion in the Environmental Health Sciences program at East Carolina University. She received a B.S. in Biology and M.S. in Environmental Health from East Carolina University. She completed her Ph.D. in Entomology with a minor in geographic information science at North Carolina State University. She completed her post-doctoral work in Arbovirology at University of Florida, Florida Medical Entomology Laboratory. Learn more.


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