There is an interesting theory about why fleas are attracted to light. Fleas use the shadows to identify their next potential host, so if they see a light source, they will quickly move toward it. Fleas can only see certain wavelengths of light, so green and yellow light are most attractive to them. Red light is not attractive to fleas, however. In addition, fleas prefer intermittent light, which simulates their host’s passing in front of a light source.
Adult fleas are attracted to green-yellow light, which has 500-530 nanometers in wavelength. The color of this light is attractive to them because they perceive it as the shadow of their potential host. Additionally, intermittent light attracts 8 times more fleas than continuous light. While bug zappers may have some effect, Colorado State University Extension and the American Mosquito Control Association concluded that they have little or no effect on flea infestations.
However, fleas prefer a green-yellow light at 500-530 nanometers (nm). They are not attracted to red light at wavelengths above 600 nanometers. Light coming from cell phones, for example, may attract fleas because of carbon dioxide produced by the device. Moreover, the lights from cellphone flashlights also simulate movement, which fleas are attracted to.
When removed from their host, fleas will die from starvation within four days. However, young fleas without a blood meal can live for as long as one week. Pre-emerged adult fleas, on the other hand, can live for as long as 155 days without feeding. It is important to remember that fleas are nocturnal insects, and they may be attracted to light when looking for food.