Attraction effect of LED luminaires and lamps on nocturnal insects
Today, electric lighting is indispensable for working at night, security in traffic, and the well-being of people. It has also been shown, however, that the significantly increased light emission experienced since the introduction of electric lighting has undesirable effects on the natural flora and fauna. Today, electric lighting is indispensable for working at night, security in traffic, and the well-being of people. It has also been shown, however, that the significantly increased light emission experienced since the introduction of electric lighting has undesirable effects on the natural flora and fauna.
Just like almost the entire animal kingdom on earth, nocturnal insects also use celestial bodies such as moonlight and starlight for their orientation. Their compound eyes perceive light in the UV range, that is, in the wavelength range below 420 nm. The human eye, on the other hand, can perceive light up to around 400 nm, as can be seen in the comparative graphic.
Nocturnal insects always fly at the same angle to the moon. If a light source with similar wavelengths is present on the natural flight route of an insect, this becomes the point of reference. The insect then stays at a certain angle to the new light source. As this light source is much closer than the celestial body, though, the insect will inevitably keep on flying around the new light source in an ever tighter spiral. When insects bump into the hot lamp housing, they burn their wings and can no longer fly as a result, which makes them easy prey for insectivores. This results in a depletion in the existence of nocturnal insects of approx. 150 animals per luminaire and night, which in turn impacts on the entire eco-system and thus on the food web of the animal kingdom. Even if this complex, ecological connection has not yet been fully researched, the effects of synthetic light emission should be reduced to maintain the natural equilibrium of fauna and flora.
For this reason, studies have been performed to research the visibility, and consequently the attraction effect of various lamps on nocturnal insects. The results of a study from Tirol shows clear differences in the flight approach behaviour, depending on the type and frequency spectrum of the light of different lamp types. This is clearly illustrated in the following overview, which perfectly demonstrates that under the same conditions LED lamps attracted less than half as many insects as the sodium lamp, which to date has been the most insect-friendly lamp.
Based on studies such as these, institutions involved in nature conservation specify a wavelength of 380 nm as the lower limit of the light spectrum. The lower limit recommended by entomologists is already at 420 nm, however. This is exactly in the blue range of the spectrum of many light-emitting diodes. The spectra of Helecta retrofit lamps as a comparison. For both light colours – 3500K and 5000K – the spectrum contains virtually no units under 420 nm wavelengths. 
Helecta LED retrofit lamps can therefore be considered particularly insect-friendly, both from a general technological aspect and as regards the light-emitting diodes used. They comply with and exceed the recommendations of environmental associations.