Just now, a housefly was bugging me a lot and I wanted to get rid of it. My mother suggested me to turn off the lightbulb and off it went. However a small flame was burning in my room. Why didn't the housefly get attracted to the flame (although it was a luminous flame)?

My first guess is because of the high temperature a flame produces. This Wikipedia article states that:

A 300 watt tubular halogen bulb operated at full power quickly reaches a temperature of about 540 °C (1,004 °F)

And a charcoal fire can produce temperatures between 750–1,200 °C (1382-2192 °F). Source.

I've seen small bugs getting attracted to large halogen lights in sports complexes. Although these two temperature ranges are a sizable difference apart, 540 °C doesn't seem cool at all. Is it really due to temperature, or is there some other reason?

  • 3
    $\begingroup$ It could be something to do with them learning to avoid flames over many years. Fire is more of a natural occurrence than halogen bulbs. It could biologically coded within them to avoid flames. The same way the average human would run at the sight of a tarantula, but doesn't get hugely scared if they just saw a plastic model of a spider, insects may know innately that fire is harmful, but newer man-made sources of light may not invoke the same biologically-driven behavioral response. $\endgroup$
    – Reece M
    May 2, 2017 at 16:03
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    $\begingroup$ Not all animals are attracted to light but those that are are motivated by mating behavior. Some female moths will seek a light source and release pheromones drawing the males to the light. The old stories about a moth flying into a flame is a myth $\endgroup$
    – waltjh
    Jul 9, 2017 at 17:21

1 Answer 1


It has nothing to do with temperature, but with the color of the light. Insects are especially attracted to lights with short wavelenghts, especially Ultraviolet (UV) light. Yellow and red light attract far less insects. (Rich & Longcore 2006). PDF

White light, like the one emitted by an average light bulb, consists of a broad spectrum, that includes UV. Halogen lights also emit UV. Flames on the other hand emit mostly red and yellow light.

Unless the flames burn at a very high temperature, then the flames turn blue. To illustrate this, my parents used to have a candlelight on gas they used during camping. This light burnt at a very high temperature, and hence the flame had a bluish color. And it did attract insects, especially moths.


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