Light emitting diodes (LEDs) are slashing carbon dioxide emissions and bringing light to millions who previously could not afford anything better than kerosene lamps. But one feature of these works of genius has been overlooked, until now – they attract fewer insects to annoy you on an otherwise pleasant evening outside.
LEDs have been around since the 1960s, but initially only existed at long wavelengths. The discovery of a blue version opened up the possibility of light that approximates what we are used to seeing by, and won its inventors a Nobel Prize.
Dr Andy Wakefield (no not that Dr Andrew Wakefield) of Bristol University decided to investigate how insects responded to the different sorts of light. He found LEDs attracted a quarter of the number of insects compared to traditional lights of similar brightness, and half as much as compact fluorescents. The work was published in Ecology and Evolution.
The study was done at 18 sites across southwest England, where the insects attracted are merely a nuisance, not dangerous. However, Wakefield hopes that disease-carrying mosquitoes in tropical countries will be similarly uninterested in the new technology, and was buoyed by the observation that the difference in attraction was particularly large among Culicoides biting flies, whose relatives can carry diseases.
“White light” LEDs, actually representing a combination of several different types across the visible spectrum, are vastly more efficient than other light producers, saving enormous amounts of money and carbon dioxide emissions. Their efficiency comes from emitting only tiny amounts of heat, whereas incandescent lights turn most of the electricity they consume into heat, with only a small amount emitted as the light we actually want.
“We were surprised by the number of biting flies drawn to the traditional tungsten lights,” Wakefield said in a statement. “We do not know why this is but we know that some insects use thermal cues to find warm-blooded hosts in the night, so perhaps they were attracted to the heat given off by the filament bulb.” Both “warm-light” and “cool light” LEDs were used in the experiment, with no significant difference found between them in their attractiveness to insects.
The research was supported by an LED manufacturing company, but given the other already established advantages of LEDs, this study doesn't seem a particularly likely case of money interfering with science to get the result the sponsors want.
The authors express concern, however, that the low cost of powering LEDs could lead to their use in circumstances where they are not really necessary, interfering with the behavior of nocturnal animals.
The proverb that honey catches more flies than vinegar has come into the 21st century.