Fly Killers - in depth

Flykiller info

To protect against The possible disease transmission risk electric fly killers were introduced into the food processing industry over forty years ago. It is important at this stage to point out that the installation of electric fly killers is not a substitute for good hygiene, however a good installation of well maintained electric fly killers is an important aspect of a good hygiene regime.

Electric fly killers have three basic functions, all of which must be present if we are to have an effective fly control system they are to attract, to kill and to collect. Attraction is achieved using lamps that emit Ultra Violet light. As UV light is invisible to the human eye traditional UV lamps had phosphors added which produce visible blue light enabling us to see when they are switched on. This blue colour has no attractant power and is purely an indicator.

Probably the most significant advance in fly killer technology in the last ten years has been the introduction of the Synergetic green / UV lamps. A review of the published scientific papers on the attraction of insects to sources of light reveals that many scientists have reported two types of light to which insects are particularly responsive. These are "near" Ultra Violet (wavelengths between 350 - 370nm) and green (wavelengths between 490 - 550nm). This information was put to practical use with the development of the Synergetic green / UV lamps, and in 1994 independent tests were carried out by an entomologist from Cambridge University using Cambridge bred flies. The results of these tests showed a consistently greater number of flies caught with the Synergetic green / UV lamps and were published in the International Journal of Environmental Health Research in 1995. Not only does the addition of green light make the lamps significantly more attractive to flies, but many stored product pests particularly moths demonstrate a greater response to green light than to Ultra Violet. This explains why fly killers fitted with Synergetic green / UV lamps are the products of choice of the leading food manufacturing companies around the world.

Whilst on the subject of lamps it is important to ensure that in food production areas fly killers are fitted with shatterproof lamps. This will ensure that should a lamp become damaged then all glass fragments will be contained and no contamination can result. One has to be sure however that the film used to make lamps shatterproof will not be degraded by Ultra Violet light and also that it will allow the maximum UV light to pass through. Another reason to purchase only quality replacement lamps. Ultra Violet light has had a particularly bad press in recent times and this has led to nervousness about the use of UV light in the proximity of humans. Fly killer lamps should emit only safe "near" UV or UV-A, as it is also known (wavelengths between 350 - 370 nm). This light is absolutely harmless to humans and the Synergetic lamps have been tested and a certificate of safety issued. The second myth about fly killer lamps involves the frequency of lamp changes. Just because a lamp is glowing we cannot assume that adequate UV is being emitted. As a lamp is used the UV output diminishes, unfortunately as UV light is invisible to humans we cannot detect this with the naked eye. It is possible to demonstrate this with sophisticated equipment in a laboratory but there is no simple method for use in every day situations and so we have to rely on well-documented maintenance procedures. High quality lamps will have a useful life of one year, however there are many cheap lamps available in the market place and most of these will last little more than sixty to eighty days! Companies that rely on price alone when choosing lamps or ignore lamp changes altogether run the risk of serious fly contamination problems. Having attracted the insects to the fly killer we then have to kill them. This is done either by electrocution or by catching the insects on a glue board. A glue board unit will frequently have a lower initial cost than an equivalent electrocution unit but will require glue boards to be changed monthly adding to the running costs. They also offer the advantage of being silent but insects actually have to land on the glue surface to be caught and larger insects can crawl off some glue boards and escape. A quality electrocution unit will kill any flying insect from the tiniest fruit fly to quite large moths without causing them to explode or stick to the killing grid.

The material and dimensions of the killing grid, the voltage across the grid and the method by which it is charged are critical to the effectiveness of such units. Too low a voltage and the smaller insects will fly right through the unit, too high and any insect entering can be exploded. The optimum is four thousand volts and this should be achieved using a quality transformer that will give a continuous flow of electricity across the killing grid. Units using capacitors that store up electricity and then discharge it as required should be avoided as the pulse of electricity that results can also cause insects to explode. Once the insects have been killed the final function of a fly killer is to collect the dead insects safely. Obviously in the glue board units killing and collection are achieved using a sticky glue board. In an electric unit collection is achieved using a catch tray. The catch tray should be of adequate capacity, and should be high sided to prevent dead insects from being blown out if there were a draught. It should be simple to remove and clean and should be robust.

Placement of electric fly killers is also an area that is frequently misunderstood and there are a few simple points to observe. Firstly the height at which fly killers are to be installed is important in terms of efficiency. As a general rule the higher up they are the less effective. In a working environment the ideal height would be between two and two and a half metres from the ground. At this height the risk of the units being damaged by moving trolleys or forklift trucks is reduced whilst maintaining maximum efficiency, they will also be easier to clean and maintain. Do not rely on area of coverage of a particular unit as the only criteria for choosing and installing fly killers. There are several factors that need to be considered before deciding on the appropriate number and size of units to be installed. These would include the number of entry points including doors, windows and any other openings for instance for pipe work or extractor fans. What is the volume of human traffic through the area to be protected? What would be the normal flying insect population? What is being produced? And where is the facility located? If it is close by a lake or a rubbish tip then there will be a greater risk than if the facility is in the middle of an industrial estate.

Fly killer units should not be installed in areas where they can be affected by air currents. Avoid areas close to air conditioning vents or where draughts may be a problem. This is because flying insects on the whole do not like moving air and units placed in these areas may be less efficient. Fly killer units are often placed directly in front of doorways the logic of the installer being that this is where the insects enter and so they will be more easily caught. In fact this will only encourage insects to enter and make the problem worse. It is better to install units off to the side of doorways ensuring as much as possible that the light does not shine out of the open door. Never ever install fly killers of any description directly above a processing line or food preparation area. The Ultra Violet lamps are highly attractive to flying insects and will attract the insects to those areas. Better to install the units away from sensitive areas to attract the insects and kill them away from the critical areas to be protected.

Finally a few points to note when considering or auditing an installation of electric fly killers:

• Are units sited correctly, check for height from the ground, and that units are not shining directly out of doors or being affected by air currents?
• Are units sited away from critical or sensitive areas?
• Are lamp changes being carried out and is a log kept of the date of changes?
• Is routine maintenance being completed including the emptying of catch trays
• and glue board changes as appropriate?
• If electric units are being used is the killing grid clean and working?
• Are the units fitted with shatterproof lamps?

To discuss the installation and/or maintenance of Flykillers, please contact Aderyn