No flies on us!
There’s a fly buzzing around the office as I’m trying to write this blog post. It’s batting against the window and trying to dive-bomb me. In short, it’s being a complete nuisance.

Flies are annoying in an office environment, but in a food manufacturing and processing environment, they can cause far greater upset. I’ve just Googled the number of fly species in the UK and, according to Buglife, The Invertebrate Conservation Trust, there are over 7,000! Some, obviously, are much more prolific than others.

Did you realise, for example, that those termed ‘filth flies’ can carry over 100 pathogens that can cause disease in humans, such as Salmonella, cholera, Shigella, Campylobacter, E. coli, Cryptosporidium, parasitic worms and fungi?

Types of fly you’re likely to encounter

Filth flies include drain flies, flesh flies and house flies. As their name suggests they move from filth to food indiscriminately. They feed on decaying and rotten food, carcasses of animals and faecal matter as well as on fresh and stored food and ingredients.

The common and lesser house fly aren’t fussy where their food comes from. Blowflies lay their eggs on rotting animal remains such as the carcasses of birds and rodents as well as dung, all of which are used as food sources for the larvae when they hatch.

Fruit flies are attracted to alcohol, fermenting sugary liquids and waste fruit, and can build up to very large numbers when these foods/breeding materials are present. You’re more likely to find them in restaurants and food preparation areas. But look out for them in bins and cracked, damp floors.

Moth flies are found in abundance in sewage works but, because the females like to lay their eggs in the type of wet, organic matter found in drains, they can also be found breeding in the layer of slime found in the floor traps of food manufacturing sites. Phorid flies, also known as Scuttle flies, frequent unsanitary conditions like blocked drains, too.

How flies contaminate food and spread disease

Flies have to convert solid matter into liquid in order to ingest it, so they deposit saliva and regurgitate juices packed with digestive enzymes to break the food down. To make room for the new food, and to lighten their bodies for flight, they will often defecate during this process. As well as this pretty revolting practice, they will also be depositing contaminated filth that they’ve picked up on their bodies as they move from place to place. There’s also the danger that a fly could land in food being processed and end up in the finished product.

Since they are so mobile, it’s easy for flies to spread disease from contaminated food sources to clean areas. They could be transmitting any number of pathogens which have the potential to lead to gastroenteritis, dysentery, tuberculosis or internal worms in humans.

Prevention is better than cure

Keeping flies out of food manufacturing, storage and preparation areas can be a challenge, but, as we’ve been told so many times before: prevention is always better than cure. There are a number of measures you can take to avoid attracting them in the first place:

Rubbish and waste

We know flies are attracted to rotting material, so always ensure that bins are not overflowing, they have lids that close and they are emptied and cleaned regularly. Additionally, refuse should be collected at least twice per week in hot weather and any equipment used to handle garbage should be cleaned thoroughly after use.

Drains
To avoid the build-up of slime where flies like to breed, drains need to be kept clear and flushed out on a regular basis with appropriate drain cleaner.

Food preparation and production areas

Food preparation and production areas need to be kept clean – including equipment, surfaces, floors and utensils. They also need to be inspected regularly to make sure that there are no breeding and feeding grounds available. Flies will be attracted to the smallest accumulation of liquid or food, so it’s important to avoid this by checking any cracks, hidden spaces or crevices. The same applies to any canteen or storage areas.

Other areas

Of course, you’ll also need to check for signs of infestation in delivery and storage areas, where spills can occur, or there might be the odd ‘bad’ apple within a delivery, so to speak.

Many features of a production facility are designed to keep flies and other pests out. Vinyl strip or automatic doors, air curtains and roll-up doors, for example do go some way to keeping them at bay. Remembering to close doors behind you and keep them closed and fitting screens on windows and vents are all good preventative measures. They allow air to circulate without letting in unwanted guests.

Keeping up with building maintenance

This is another essential element of pest control. You need to be vigilant of any gaps appearing in the fabric of the building. These could provide the potential for flies and other pests to enter. Any flies that do enter can be controlled by the use of UV light or pheromone traps.

Pest control is just one element of a longest of pre-requisites to food safety