Top pests in hotel and commercial kitchens

Pests are a public health and business risk. They can cause damage to buildings, fittings, furnishings and food products, transmit disease, cause unsightly marks and smells.

They affect customers in several ways, including causing illnesses, irritating bites, bad feeling, which can be expressed in many social media platforms and review sites, and loss of custom.

On this page you can find detailed information on these pests that affect hotels and commercial kitchens:

• Cockroaches
• Flies
• Stored product insects
• Rodents

Pest infestations impart costs to businesses from:

• treatment to eradicate pests;
• replacement of contaminated stock or defaced items;
• loss of reputation;
• loss of business; and
• potential litigation from the public and regulatory authorities.

Businesses providing products and services to the public are expected to give pest control a high priority. Hotels and restaurants have a responsibility for protecting public health by preventing contamination of food and transmission of pest-borne diseases inside their premises.

Food safety legislation (in the EU Regulation (EC) 852/2004) mandates that food handling businesses exclude pests and prevent food contamination by taking effective measures.

Rodents

Rats and mice are attracted by food supplies and do not venture far from their shelter or nesting sites, so in a large facility will nest close to accessible food stores.

Rats and mice are capable of a rapid increase in population given an abundant food supply, due to the number of litters they are capable of producing and the time to maturity, shelter from predators and benign environmental conditions inside a building.

Hazards from rodents

The hazards from rats and mice include:

• damage to buildings and fixtures; the most common problem with the brown rat is damage to electrical equipment, but they can also cause extensive damage to sewer systems by burrowing;
• contamination along access routes with urine, droppings, and filth picked up from the environment;
• damage to food containers and packaging;
• eating the food in stores and packages;
• contamination of food with droppings, urine, filth;
• transmission of a large number of diseases, including Salmonellosis, Leptospirosis, Toxoplasmosis, Lyme disease, rat-bite fever;
• rodents carry ectoparasites, including ticks, fleas, lice and mites and are therefore also vectors for the diseases that these carry.

Signs of rodents

Rats and mice leave distinctive signs that show which pest is present:

• droppings, which have a different size and shape for each species;
• sightings of live or dead animals;
• noises: squeeks, gnawing sounds, scurrying sounds;
• smudge marks along runs caused by their oily fur;
• tracks in dust or powder put down to indicate their presence;
• gnawing of building materials, wiring, food and packaging: the gnaw marks are different;
• urine stains are left along trails by both rats and mice and can be detected using UV light;
• urine pillars form where mice infest an area over a long period — and would show a serious failure in pest control.

Rodent control

Control of rodents involves the elimination of harbourage in and around buildings and preventing access to food, water and shelter. There may be many points of entry to a building, such as cracks, vents, pipes, cabling, drains, doorways, windows, screens, where measures can be taken to prevent access.

Any rodents present must be controlled using traps or poison according to acceptable practices and legislation, including food law, health and safety, environmental and wildlife laws.

Use of rodenticides

Rodenticides used must be registered products, placed in secure bait stations and restricted to areas where food is not handled. If stored on site they must also be stored in suitable conditions that prevent contamination from the poison in food products and the environment.

Expertise is needed to determine the type of bait used, where it should be placed and the frequency, the monitoring regime and the documentation, which is best done using an outside contractor. If done in-house, staff will need to be certified to handle the chemicals and carry out the rodent control activities.

There are specific requirements for documentation in food standards and legislation, such as maintaining maps of all bait stations, records of sightings, records of training of staff, and the monitoring regime, therefore it is important to have trained personnel responsible for this.

The Campaign for Responsible Rodenticide Use (CRRU) promotes the safe use of rodenticides to ensure they are used correctly and in ways that minimise exposure of wildlife and other non target animals. It promotes safe and responsible use through a seven-point Code of Practice:

• always have a planned approach;
• always record quantity of bait used and where it is placed;
• always use enough baiting points;
• always collect and dispose of rodent bodies;
• never leave bait exposed to non-target animals and birds;
• never fail to inspect bait regularly;
• never leave bait down at the end of the treatment.

Rentokil’s technicians are trained in the safest and most effective use of second generation anticoagulant rodenticides (SGARs) that meet the strict requirements of the CRRU stewardship scheme. In the UK our technicians are British Pest Control Association (BPCA) certified.

As a professional organisation we ensure our front line staff are fully aware of the risks professional products can pose to wildlife and apply this knowledge to reduce any risks to non-target species.

Cockroaches

Cockroaches are the most common type of crawling insect that infests food handling businesses. They cause particular problems because of their size, giving them the ability to hide in small places, their varied diet, rapid reproduction and the diseases they can carry.

Cockroaches are primarily nocturnal, sheltering in the daytime and coming out at night to find food and other sites for shelter. They shelter in dark places such as cracks, crevices, drains, sewers, inside equipment and furnishings and hidden spaces that provide the right temperature and humidity. These places are also hard to reach using normal cleaning and sanitation methods.

Three most common cockroach species:

• German Cockroach (Blatella germanica): the adult is about 12-15mm long and light brown. It prefers wet, humid conditions and is especially associated with infestations of kitchens and food storage areas, but also infests bathrooms, vehicles, offices and administrative areas. It is thought to have originated in East and Southeast Asia and is now the most common cockroach pest in buildings worldwide, maintained by heating systems in cooler climates — it is rarely found outdoors. Its temperature preference is 20–27°C.
• American cockroach (Periplaneta americana): the largest cockroach, with adults 35-40mm long and reddish brown. It requires warm, humid environments to survive. They are found in drains, sewers, basements, storage rooms and waste storage areas. Temperature preference is 24–31°C.
• Oriental cockroach (Blatta orientalis): the adult is 20-25mm long, intermediate between the other two and has a dark brown or black body. It prefers cooler, dark and damp places to shelter, such as basements and drains, and can be found in storage rooms and waste storage areas. Temperature preference is 20–29°C.

Hazards from cockroaches

• Diseases and allergens: cockroaches can carry a large number of disease-causing bacteria, including Salmonella, Staphylococcus, Listeria, E. coli, and also fungi, viruses and parasitic worms;
• they feed on decaying matter, mould, faecal matter in sewers, from rodents and birds, and animal carcasses, which can then be transmitted into the food production and serving environment on their bodies or from excreta;
• they defecate along their pathways and frequently expel saliva on surfaces to ‘taste’ their environment;
• droppings and bodily secretions stain and leave a foul odour that can permeate infestation areas, food and packaging;
• cast skins and egg cases contaminate products and food packaging;
• droppings and shed skins contain allergens, and heavy cockroach populations can trigger asthma attacks in both guests and staff.

Cockroach prevention

Good sanitation practices prevent infestations and pick up the presence of cockroaches:

• cockroaches can feed on small residues of food left from spills or in food preparation areas, so good cleaning practices which eliminate the residues quickly will deny them a food supply;
• store food in cockroach-proof containers: they eat cardboard so this should not be used for storage;
• maintain drains in good condition to prevent accumulation of food debris and means of access and shelter;
• remove waste from food production areas;
• use a garbage container design that denies access to all pests,
• position garbage containers away from the food storage and processing areas, empty and clean them frequently;
• good building design and maintenance can reduce the risk of cockroach access eg through spaces around pipe and cable ways, vents, screens, windows, doorways, sewers; and harbourage in small spaces such as junction boxes;
• a good inspection regime for equipment, buildings and deliveries will pick up infestations and identify risks quickly.

Cockroach lifecycle

The German cockroach is the most widespread and reproduces more rapidly than the other common cockroaches. After mating, the female produces an egg case containing about 30 eggs and carries it at the tip of its abdomen for about 30 days while the juveniles mature, until 1–2 days before hatching. The juveniles hatch looking like small adults, but without fully developed wings.

The other species deposit the ootheca in a suitable location to incubate for several weeks or months. Young immature cockroaches undergo gradual metamorphosis. They resemble adults and have similar feeding habits, but they do not have fully developed wings and are not reproductively active. Immediately after molting, cockroaches are white, but their outer covering darkens as it hardens, usually within hours.

Cockroach control

A number of treatments are available for control of cockroaches, including sprays, aerosols, dusts and bait. There are stricter regulations for control near food handling and storage areas, to prevent contamination of foods with poisons.

The insecticides used must be permitted for use by the relevant local or national authority and will require competent, trained personnel to apply them.

Rentokil also has chemical-free control methods suitable for sensitive business environments and Insect Monitor Units to detect signs of activity.

Flies

A number of fly species are attracted to food odours generated by kitchens: fruit flies, drain flies and filth flies, which includes house flies. Different fly species are attracted to different food products, including fermenting sugars, oils and fats, carbohydrates, and decaying proteins and vegetable matter. For pest control it is important to identify which species is present as each has different attractants and breeding habits.

Fruit flies are attracted to fermenting sugary liquids, in which they can feed and breed in very small amounts — in bars, kitchens and restaurants. The liquid can accumulate in:

• garbage containers;
• over-ripe fruit, and some vegetables;
• old drink bottles;
• in drains;
• in spills;
• in cracks in wet floors.

Drain flies are attracted to rotting food, sewage and other organic waste material. They lay eggs in organic waste that can build up in drains or polluted shallow water. They can breed in the gelatinous bacterial films — biofilms — that form on surfaces in drains, septic tanks, compost, and are resistant to cleaning and pest-control chemicals.

House flies breed in decomposing waste such as rotting food and animal faeces.

Blow flies lay eggs in rotting meat, including kitchen and restaurant waste, and dead rats, mice and pigeons.

Risk from flies

In warm conditions and with food supplies flies can multiply rapidly. They feed on faecal matter, garbage, rotting materials as well as stored and processed foods that will be present around commercial kitchens. They will regularly move between the contaminated food sources and clean areas, carrying contaminated filth on their bodies as well as microorganisms internally.

Flies can carry many microorganisms that cause disease in humans, including Salmonella, cholera, Campylobacter spp, E. coli, Cryptosporidium, parasitic worms and fungi.

Flies can pick up contaminated materials on their bodies, feet and mouth parts. Some regurgitate digestive juices and defecate while feeding and resting, contaminating foods and surfaces with microorganisms that can cause disease or decay. Fruit flies are not generally considered to be as great a health risk as other flies. However, they can also carry spoilage microorganisms and diseases.

Controlling flies

The application of standard hygiene practices are particularly important for controlling flies to reduce the attractive odours, feeding material and breeding sites.

These include:

• adequate food hygiene practices in kitchen and restaurant areas;
• food preparation areas, including floors, walls and equipment are cleaned and inspected regularly, including in cracks, crevices and hidden spaces where traces of food and liquid can accumulate;
• supplies are not brought in or stored in a rotting state;
• garbage is disposed of regularly — at least twice a week in hotter climates;
• garbage containers are cleaned and can shut properly;
• drains are kept free of accumulating organic matter and cleaned with appropriate cleaner.

Maintaining barriers to flies, including:

• use of screens on windows and vents in kitchen areas, maintained in good condition;
• doors are kept shut when not in use;
• the building is maintained to prevent gaps appearing in any part of the building fabric that would allow insects to enter;
• UV light traps to catch flies hygienically in food preparation and storage areas.

Elimination

As a last resort pesticide is applied using approved products applied by trained personnel following accepted practice.

Stored product insects

Stored product insects (SPIs), also called pantry pests, include beetles, weevils, moths and mites (which are arachnids) that can infest food in storage. Most dried food products are susceptible to pest infestation, including cereal products, seeds, nuts, dried fruit, spices, powdered milk, tea and preserved meats. All stages of the pest can be present simultaneously in the food: egg, larva, pupa, adult.

SPIs are more likely to infest products that have been opened but can also enter packaging made of paper, cardboard, plastic, cellophane and foil, chewing through the packaging material or crawling through folds and seams. Larvae, especially, can make very small entrance holes that are difficult to detect.

Insects and can contaminate large quantities through physical damage, faeces, cocoons, etc and the introduction of microorganisms that cause further degradation, making food unfit or unacceptable for human consumption or for use in food preparation.

Food can become infested at any point in the supply chain, but is more likely to be infested in stores or when kept on shelves for long periods.

Common pests

The common stored product pests and the foods they infest are:

Moths

• Indian meal moth: nuts, dried fruit and grain.
• Mill moth: flour.
• Tropical warehouse moth: stored cereal, nuts, dried fruit, oil seeds and oil cakes.
• Warehouse moth: cocoa beans, chocolate confectionery, dried fruit and nuts.

Beetles & weevils

There is a very large number of species of beetle and weevil that feed on dried foods such as: cereals/grains, flour, seeds, nuts, pulses, dried fruit, chocolate, spices and processed products including pasta.

Mites

• Cheese mite: cheese, nuts, dried eggs, fruit, flour, tobacco.
• Flour or grain mites: cereals, dried vegetable materials, cheese, corn and dried fruits.

Stored product pest control

Signs of stored product pests include:

• damage to stored products, such as small holes in nuts or grain;
• live or dead insects (small beetles and moths), larvae, pupae or silken webbing on food storage bins;
• infestation, holes, larvae or webbing on the outside of packets or bags;
• larvae, pupae or silken webbing in food harbourages in cracks and crevices around shelves or on machinery;
• larvae, pupae or silken webbing in food spillages;
• larvae, pupae or silken webbing on beams and window sills; and
• pests caught in insects traps.

Following basic practices can minimise the risk of infestation:

• throw away food that is infested with pests;
• buy foods in quantities appropriate for the amount used, so they are not kept in storage for long periods;
• use older products first and use up opened packets first;
• dispose of old products;
• inspect food and packages on delivery: for unbroken packaging, freshness, packaged/use-by date;
• store foods in tight closing containers or in a fridge or freezer where appropriate;
• keep food storage areas clean, including shelves and cupboards, and remove spilled foods such as flour and crumbs; vacuum the area thoroughly, especially in corners, internal edges and cracks; and
• do not use pesticide sprays: they may contaminate food and are unlikely to be effective for pests in packaging.

Bibliography

• UC IPM. Cockroaches. University of California Agriculture and Natural Resources, Integrated Pest Management Program. (link)
• Keener, K. Safe food guidelines for small meat and poultry processors. A Pest Control Program. Purdue Extension, Purdue University.
• Lupo L. Control of small flies. Quality Assurance Magazine. 31 March 2015.
• Lupo L. Controlling Flies: Large and Small. Quality Assurance Magazine. 13 August, 2013.
• Lupo L. Cockroach FAQs. Quality Assurance Magazine. June 3, 2014.
• Sela, S et al. Mediterranean Fruit Fly as a Potential Vector of Bacterial Pathogens. Appl Environ Microbiol. 2005 Jul; 71(7): 4052–4056. doi: 10.1128/AEM.71.7.4052-4056.2005
• UNIDO. Good Manufacturing Practices: Pest Control. Paper 9. (link)
• WHO. Public Health Significance of Urban Pests. Copenhagen, 2008. ISBN 978-92-890-7188-8. (link)