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The pest risks to buildings during the COVID-19 lockdown

During the coronavirus crisis, governments around the world have ordered the shutdown of non-critical businesses and services to reduce the transmission of the virus to protect the population. Other buildings that are classed under essential services may have reduced staff as only essential workers are regularly on site. For infection control, businesses may also restrict staff of external contractors from accessing their premises.

This has left many buildings lying empty or with much reduced human presence, resulting in greater risk of pest and maintenance problems. If pest control technicians can’t access a site, there’s a risk of infestations occurring and pest numbers multiplying in an uncontrolled manner.

Buildings in multiple sectors are affected, including commercial, hotels and restaurants, education, industrial and residential, where homeowners will be reluctant to allow people in to protect themselves from infection. With no or few people and little activity, these buildings have become a perfect habitat for many types of pest. An additional problem is that if a building is left empty for a long period the insurance policy may not provide cover.

When food’s also nearby, pest numbers can grow rapidly, which can result in:

  •       physical damage to the buildings and fittings
  •       a large pest infestation that’s much harder to eradicate
  •       contamination of the site with debris from, for example, nesting material and droppings
  •       contaminated surfaces carrying health risks from the many diseases that pests can carry
  •       infestations of other pests carried as ectoparasites, including ticks, fleas, mites, lice and also beetles and weevils that infest nests but are also stored product insects

Pest infestations cost businesses an estimated £11.8 billion across five countries, according to a Rentokil commissioned survey. Over a quarter of businesses reported damage to electrical equipment during a rat infestation and 15% of businesses reported loss of revenue due to customer trust following an infestation.

The main pest threats to buildings


Rats and mice are capable of an exponential increase in population when there’s an abundant food supply. They produce multiple litters in a year and several generations of young mature and produce their own young within a year. In addition, the shelter from predators and benign environmental conditions inside a building produce a higher survival rate than in the wild.

During the pandemic many food businesses such as restaurants and cafés have been shut down, resulting in local rat populations suddenly having their regular food supplies disappearing. This can lead to starvation, which drives them to leave their normal territory to look for new food supplies. Rats even change their normally nocturnal habits to find food during daytime – this unusual behaviour has already been reported in New Orleans.

These starving rats are an increased risk to nearby buildings where food’s still present, including, hospitals, care homes, food retail stores, food stores and warehouses, and homes. Food waste bins that have not been emptied will also attract rats.

Risks from rodents

The hazards from rats and mice include the following.

  • Damage to buildings and fixtures by gnawing: the most common problem with the brown rat is damage to electrical equipment and a risk of fire caused by wires shorting. Rats 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 food in stores and packages
  • Contamination of surfaces 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


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

Cockroaches 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 basic cleaning and sanitation methods.

Risks 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 any decaying organic matter, mould and faecal matter in sewers, which can then be carried into buildings on their bodies and in excreta
  • They defecate wherever they crawl and frequently expel saliva on surfaces to ‘taste’ their environment
  • Droppings and bodily secretions stain and leave a foul odour that can permeate infested areas and goods
  • Cast skins and egg cases contaminate food products and packaging
  • Asthma caused by allergens in the droppings and shed skins


A number of fly species can be pests around buildings, breeding in decaying organic matter such as food waste, droppings, dead animals and drains. These species include fruit flies, drain flies, house flies and bluebottles. Buildings also provide sites for some species to overwinter. Different fly species are attracted to different food products, including fermenting sugars, oils and fats, carbohydrates, and decaying proteins and vegetable matter.

Risks from flies

In warm conditions and with food supplies, flies can multiply quickly. They feed on faecal matter, rubbish, rotting materials and stored and processed foods. They will regularly move between the contaminated food sources and clean areas, carrying contaminated filth on their bodies and microorganisms internally.

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 can also carry spoilage microorganisms and diseases.

Flies can carry many microorganisms that cause disease in humans, including Salmonella, cholera, Campylobacter sppE. coliCryptosporidium, parasitic worms and fungi.


A few species of birds are able to thrive in urban areas. They’re adapted to the nesting and roosting sites in the ledges, sills, roofs and gutters of buildings and the ready sources of food provided by human food supply activities in the vicinity. They can exploit gaps in the roof, walls, and open or broken doors and windows for entry and take shelter in spaces such as under roofs. The most common bird pests are pigeons, house sparrows, seagulls and starlings.

Risks from birds

Birds can cause the following type of damage.

  • Fouling: droppings accumulate around roosting sites, fouling the outside and inside of the building if they gain entry, surrounding areas, vehicles and produce
  • Physical damage: birds can dislodge roof tiles, damaging insulation in roof spaces, and corrosion caused by chemical action of the droppings attacks stone, metal, paintwork and other building materials
  • Water damage: nests block guttering and drain pipes, causing flooding on the roof, internal leaks, rotten timbers, metal corrosion, damaged plaster and other wall coverings and flooring inside the building. Wet areas can then become breeding sites for flying and biting insects and sources of fungi and mould
  • Spread of diseases: bird droppings can contain many types of pathogens that create a health risk by contaminating surfaces. Pathogens include SalmonellaE. coliHistoplasmaChlamydia psittaci (which causes psittacosis)
  • Spread of insects and parasites: ticks, fleas, lice and mites are carried by birds and can infest their nests and spread around the building. Various beetles, moths, flies and mites that feed on nest detritus can infest nests, including carpet beetle, fur beetle, biscuit beetle, clothes moth, dust mite and other stored product insects

How to protect buildings from pests during the coronavirus lockdown

It’s essential to continue maintaining buildings and pest control services to prevent pests accessing buildings and to prevent infestations becoming a greater financial risk. Pest infestations also lead to reputational damage and may delay the return of a building to normal use when the coronavirus lockdown restrictions are lifted.

A professional pest control service can provide an integrated pest-management plan that controls pests efficiently and discreetly to protect the building, stock, equipment and provides a safe place for staff. 

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