As Autumn approaches we are coming into Cluster Fly Season (weather dependent but approximately October to April).

Location: Numerous locations, but usually in lofts and roof spaces. South-facing windows and walls often favoured.

Detection: Visual sightings of large numbers of adults.

There are three main species of fly collectively known as cluster flies. They are Musca autumalis, a small fly of about the same size and colour as the house fly, Pollenia rudis, a larger fly dull brown/grey in colour, and lastly Dasyhora caynella which is about house fly size and shiny green/blue in colour.

Biology:

Cluster flies, particularly Pollenia rudis are very common occurring throughout Great Britain. The adult flies during the summer months, lay their eggs in the earth or in animal dung. Permanent areas of grassland are favourite sites e.g. permanent grazed pasture or parkland as solid cultivation such as ploughing disrupts the flies breeding cycle. The larval stage is parasitic, entering earthworms and feeding upon them until emerging as an adult fly.

Cluster flies migrate from outdoors into the lofts of houses and farm buildings during the autumn months causing a nuisance to householders. Obvious signs of an infestation is a roof space containing a large quantity of lethargic flies and a quantity of dead flies. Unless the loft is used for storage purposes or is accessed regularly the flies will hibernate successfully leaving in early spring dependent on the weather.

Reasons for control:

Cluster flies are not damaging to property when they enter buildings in the autumn purely to hibernate over the cold winter months. As mentioned above they feed on decaying vegetation and earthworms. Cluster flies are not to be associated with dead animal bodies, faeces and the resulting maggots. Fibre glass insulation material in lofts can look unsightly if covered with the bodies of flies that have not hibernated successfully although its insulation properties will not be altered and no damage to the roof structure will occur.

If the loft is home to a hibernating colony of flies, first floor lighting diffusers or sunken spot light lenses can become full of dead or dying flies. This often occurs in houses where the loft area has been converted into a living room. In most buildings built after 1950, the external roof covering has an under felt layer. Cluster flies can successfully hibernate undetected between these two layers. Often cluster flies can be seen basking on sunny grassland or resting on south facing walls of buildings. Cluster flies, like birds, return to roof spaces previously occupied so re-infestation is almost inevitable.

Control/Treatment:

Unfortunately the only option available is to try and control the number of flies by either:-

Insecticidal space spray by us or another pest control company (N.B. if bats are present in your loft/attic this will not be possible). If you are not in our area please see the BPCA’s web site to locate a pest control company near you search BPCA member. Number of visits required will depend on the time of year the treatment is carried out and also on weather conditions (mild autumn) as to when flies come in to hibernate.

The use of fly control units also works well (N.B. it is not recommended that electric grid machines are used in loft areas/roof voids, however if you wish to use this type of machine it is important that these are used with an extra deep cluster tray and checked on a regular basis). Please see our online eshop www.hygieneshop.co.uk for fly killer units which are suitable for controlling cluster flies.

Below photo shows a glueboard covered in cluster flies:-

N.B. If bats are present in the roof space, then it is not recommended that any sort of fly control is used.

When a fly lands on your food, as flies cannot chew they have to suck up their food, in order to soften it up they vomit on it, the digestive juices, enzymes, and saliva in the vomit begin to break down and dissolve the food. The fly can then suck up the liquid food with its sponge-like mouth parts and its proboscis. The fly’s feeding technique underlies, the main mode of food contamination with disease pathogens and spoilage organisms.

The fly is a highly mobile pest, able to fly from filth to food carrying with it a wide range of disease-causing organisms on its body. There are many thousands of species of flies; however, relatively few interact with humans. Those that do are among the most destructive of pest species, spreading diseases to man and domesticated animals as well as contaminating food and packaging.

It is every company’s responsibility to ensure adequate measures are being taken to avoid infestations by flying insects, especially where food is being prepared, packed or stored. At the same time home owners are becoming more aware of the risks and also want to offer the same high standards of care to their families.

Fly control is integrated; this means that no one specific method of control will control flying insects 100% of the time. As a result of this, flying insect control has to be integrated for example with fly screens on open windows or fly screen doors.

HACCP House Rules in relation to Flyscreens

• Windows opening directly into food preparation areas must be fitted with screens capable of resisting common flying insects (ideally apertures should be of 2mm2 or less)
• Screens must be removable to allow for cleaning
• Kitchen doors which open to the outside air and which are opened for lengthy periods must also be suitably screened using a close-fitting insect-proof screen door

Vermatech supply and install bespoke flyscreens for commercial customers only such as schools, restaurants, public houses. Please contact us to arrange a survey of your premises either by using our online contact form or by telephoning us on 0800 781 4059.

When should you change the ultra violet bulb in your fly killer?

Ultraviolet light is invisible to humans and deteriorates over a short period of time, usually around 12 months. Blue light will still be emitted from the tube, but this will not attract the insects. Just because a tube lights up that does not mean that it is producing enough of the correct range of UV to attract flying insects. It is therefore important to change tubes at least every 12 months, preferably at the onset of warmer weather. We sell a wide range of ultra violet tubes please see our online Internet shop at www.hygieneshop.co.uk or phone us on 0800 781 4059 to ensure you are ready for the fly season.

Fly Control Units

We also sell a wide range of British made fly control units both electric grid and glueboard. Please see our Internet shop at www.hygieneshop.co.uk or phone us on 0800 781 4059.