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Nocturnal insects

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82_thumbInsects are the class with the largest number of species on the planet and represent the majority of the planet's biodiversity. They are very important pollinators of plants and an irreplaceable link in the food chain.
Insects active at night can be divided into positively phototaxic – those attracted by light, and negatively phototaxic – those running away from the light. The sensitivity of the insect eye is different to the human eye; it reaches far into the ultraviolet part of the spectrum that is not visible to humans. Therefore it is recommended to use the yellow spectrum of light in luminaires and not UV or blue light, which attract the positively phototaxic insects the most. There are several explanations of why insects fly towards the light; the most likely explanation is that they mistake street luminaires for the moon. While flying, it is possible that they orient themselves in relation to celestial bodies and fly at a constant angle in relation to the sun or the moon. In this way, they maintain the right direction. In the proximity of artificial lights, however, they start flying at a constant angle in relation to the luminaire. Because the luminaire, unlike the moon, is very close, they start approaching it and must thus constantly adjust their direction of flying. In this way, they are approaching the light in a spiral and finally fly into it. In the glow of the light, some of them start circling around it constantly, and others get numbed by the light. In both cases, they do not feed and reproduce and often die from exhaustion.

This is also problematic for negatively phototaxic insects – those that avoid light. Because there are an increasing number of surfaces now being illuminated, their living environment is getting smaller and more fragmented.


Insects approaching the luminaire in a spiral – they are trying to fly at a constant angle to the light.










Eisenbeis, G. 2006. Artificial Night Lighting and Insects: Attraction of Insects to Streetlamps in a Rural Setting in Germany. In: Ecological Consequences of Artificial Night Lighting (Rich, C. & Longcore, T., ur.), str. 281-305: Island Press.
Frank, K. 2006. Effects of Artificial Night Lighting on Moths. In: Ecological Consequences of Artificial Night Lighting (Rich, C. & Longcore, T., ur.), str. 305-345: Island Press.
Frank, K. D. 1988. Impact of outdoor lighting on moths: an assessment. Journal of Lepidopterists' Society, 42, 63-93.
Svensson, A. M. & Rydell, J. 1998. Mercury vapour lamps interfere with the bat defence of tympanate moths (Operophtera spp.; Geometridae). Animal Behaviour, 55, 223-226.

Literature in Slovenian

Trilar, T. 2001. Vpliv svetlobnega onesnaženja na žuželke. In: Svetlobno onesnaženje: javna predstavitev mnenj (Bevk S., Mikuž H. & J., P., ur.), str. 117–123. Ljubljana: Državni zbor republike Slovenije.