Fly screens and insect exclusion: keeping flies out of kitchens

Warm weather brings flies, and in a kitchen they are more than a nuisance. Flies feed on waste and decaying food, then land on work surfaces, utensils and uncovered food. Keeping them out is far easier than dealing with them once they are inside and breeding. Here is how.

01Why flies matter

House flies, bluebottles and other filth flies breed in rotting food, waste and animal matter. When they land, they leave behind whatever they picked up last, and they feed by regurgitating onto food. Fruit flies breed in overripe fruit, spilled drinks and food residue, and drain flies breed in the film that builds up inside drains and gullies. Each of them points back to a source, and dealing with the source is the first step.

02Everyday steps that keep flies down

• Cover the bins. Use bins with well-fitting lids, keep them closed, and empty them regularly. Keep external bin stores clean and away from doors.
• Seal and store food. Keep food and ingredients in sealed containers or in the fridge, and never leave food out on surfaces.
• Clean up straight away. Wipe up spills, especially sugary drinks, and clear food residue from under and behind equipment.
• Watch the fruit. Throw out overripe fruit and vegetables, or keep them chilled.
• Keep drains clean. Clean drains and gullies regularly so there is no organic build-up for drain flies to breed in.
• Keep doors and windows shut where they open onto food areas, unless they are screened.

At home, the same rules apply, along with one more: do not leave pet food down once your pet has finished.

03Fly screens and insect exclusion

Kitchens need ventilation, and staff need doors they can get through. Fly screens let air in while keeping flies out. Insect exclusion covers the other routes in as well:

• Window screens, fixed or removable, so windows can be opened for ventilation.
• Door screens and strip curtains on doors that are often open, such as back doors and delivery doors.
• Mesh over vents and openings, including roof and extract vents, without restricting the airflow they are there for.
• Proofing gaps around pipes, ducts and frames that flies and other insects can use.

The right combination depends on the building, how the doors are used and where the flies are coming from. That comes from looking at the premises, not from a catalogue.

04Screens and fly control units together

Screens stop most flies getting in. Flying insect control units catch the ones that still manage it, and what they catch shows whether there is a source on site. In food areas the two work best together. Our guide to flying insect control units covers the units in more detail.

05When flies are already breeding

If flies are breeding inside, with maggots in waste, a build-up in a drain or a carcass in a void, screens alone will not solve it. The source has to be found and dealt with first. A sudden cluster of flies in one room with no obvious cause often means something has died nearby.