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FLY KILLER LAMPS

Traditionally lamps used in fly killers appear blue and emit light only in the UVA spectrum. The intensity of the light, the UVA output and the exact spectral peak varies between different lamp manufacturers. UVA output can vary significantly with a good quality lamp emitting around 10% UVA (measured as a percentage of total lamp output) down to half that for a poor quality low cost lamp. There are heated debates between the manufacturers as to the effective merits of their lamps but what is not in question is the degradation of the UVA phosphor in all lamps.

Even a good quality lamp will lose 15% of its UVA initial output in the first 100 hours of use and a further 20% in the next 900 hours i.e. after 6 weeks the lamp is 65% effective. After 30 weeks the UVA output is down to 50% and declines steadily thereafter.

Green light output, or any other light in the visible spectrum, is virtually unaffected with time. Degradation of the phosphors that make up the green spectral peak is under 2% in the course of the year.

These facts about phosphor degradation might suggest that the effectiveness of Synergetic lamps in attracting insects should increase in time relative to UVA lamps. This is because whilst the UVA output in both the Synergetic and UVA lamps decreases by 60% over the course of a year, the Synergetic lamps maintain over 98% of the output of the green attractant phosphors and it is known that many insects have an attractant peak in the green spectrum.

To test this Insect-O-Matic scientists looked at catch ratios with 12 month old UVA versus Synergetic lamps against houseflies. Insect-O-Matic units fitted with the Synergetic lamps caught on average 82% more flies than those with the UVA lamps (Figure 1).

Figure 1.

This result confirms the hypothesis that Synergetic lamps become more attractive to house flies over time relative to UVA lamps.

Some major lamp manufacturers try to promote their version of green light to the industry. These lamps emit highly intense green light with no UVA and are more commonly used in discos and chicken rearing pens. In-house tests found these lamps to be no more effective than common white fluorescent lamps in attracting flies.

Figure 2.

Figure 2 shows the spectral output from a Synergetic lamp.

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