Fly Control - Urban Myths

The results of our testing so far have revealed a number of urban myths about EFKs, a few of which should certainly be laid to rest:

Higher wattage EFK units catch more flies

Not true. The wattage of a fluorescent lamp is a measure of the power it draws from the supply, not the quantity of light it produces. For example: the same quantity of light (around 750 lumens) is produced by a 60W incandescent bulb, a 42W halogen bulb and a 15W compact fluorescent lamp.

Equally, the light produced must be of the correct wavelength (350 or 365 nm) to influence the behaviour of house flies. Producing more light at other wavelengths can have no affect on the behaviour of flies.

The more UV-A an EFK emits, the more flies it will catch

It certainly helps, but maximising UV-A output can lead to other unintended outcomes. For example: tests conducted at Rentokil’s European Technical Centre in Horsham have found that fitting reflectors behind the bulbs in a unit will increase the amount of UV-A emitted into the room, but also provide a landing site for flies where they can perch without capture. Therefore the unit’s catch rate is reduced despite the reflectors attracting more flies to the unit.

Green light / pheromone lures / yellow glueboards / glueboards with spots on are most effective at attracting flies

Probably true, but not that relevant. There are scientific studies on the behaviour of flies in laboratories that show the fly’s behaviour is influenced by a number of different sensory cues including glueboard colour and contrast, pheromone lures and green light. Equally there are also scientific studies that show no significant attraction to any of these cues when they are used in the field. The reasons for these different findings are likely due to the range of different sensory information the flies experience outside the uniform environment of the laboratory.

Different insects are attracted to different wavelengths of light though, and it is important to keep in mind what it is you are hoping to catch. In addition, an end user may prefer a black glueboard that disguises the appearance of captured flies.

Tests conducted at the European Technical Centre found no significant difference in catch rates when glueboards of different colours and contrast were compared in the same units. A range of different units from different manufacturers were tested in this way.

The larger the EFK’s stated coverage area, the better it is at catching flies

Not true. Coverage figures quoted by EFK manufacturers have very little application in the field. For example: a wall-mounted unit covers half the area that would be covered by a suspended unit with the same number of lamps. The area covered is

The area covered by a wall-mounted unit is a 2:1 rectangle of 4d2/2 = 2d2 = 12.5n m2

Where: d = distance in metres from unit to minimum effective level = √6.25n
n = no. of 15W lamps

One assumption is that there is no significant reflection of UV-A by the back-plate or chassis.
A second assumption is that the area in front of the unit is completely unobstructed
A third assumption is that the power (W) of the bulbs is generating the same amount of UV-A per 15W bulb

In the field coverage depends almost entirely on what the surroundings are. In a store house with pallets stacked floor to ceiling, you are going to need more EFKs than in a perfectly empty room, and if there is a lot of ambient light you will need more than in a pitch-black roof space.

The catch rate of an EFK in the field is going to depend upon the environment it is in and the placement of the unit. A high-powered EFK is no substitute for the experience of a trained field biologist.

The bigger the EFK’s catch area, the more flies it will catch

Not true. If flies are not attracted to the unit, they will not be caught on its glueboards. The worst performing unit tested at the European Technical centre had one of the largest catch areas: equally, it had one of the lowest UV-A output readings.

All EFKs are much the same

Not true at all. There are a multitude of factors that influence EFK catch rate including:

• Size, position and orientation of the glue board(s)
• Amount of sites within the unit where a fly can perch without capture
• Cover design
• Distance between glue board(s) and lamps
• Colour of unit.
• Degree of contrast between the unit and its surroundings
• Type of adhesive used on the glue board(s)

Optimising catch rate may also be a lower priority to an end user to factors such as aesthetics, ease of servicing and the environment the unit will be used in. The Rentokil Luminos range has been designed to maximise catch in all market segments.