RE: Moths and Light

Deborah:

Great question. I am going to answer it in parts.

One is the not all moths are attracted to light, some don't care for it, some like ultra-violet light, some don1t care if they have light or not. So, we will start with SOME moths are attracted to light. SOME of those moths are attracted to artificial light. SOME of those moths are attracted to different types of artificial light.

But generally speaking moths that prefer the day are attracted towards light. Moths that are active at night prefer darkness.

Life was probably not as complicated for light seeking animals before artificial light. Insects just worked with light from the sun or the moon, or large fires. Animals may have been attracted to moon light, however, it is probably not likely they would try to fly to the moon. They were probably more attracted by the illumination given off by night blooming flowers which had a reward at the end, food. As humankind learned how to control fire, then animals had to deal with a new source of light. A child sitting by a campfire 1,000 years ago may have wondered why insects were drawn by the light from the fire.

Moths that are attracted to light are phototropic. Generally, light coming from the sun and from an artificial light have very much the same properties. That is what SOME insects are attracted to - light. But others are attracted by light that has short bandwidths like blue or violet light than they are those with longer bandwidths like yellow or red light, SOME insects prefer light that emits ultra-violet light.

Light is a way in which insects find food. Moths at night are probably seeking night blooming flowers that reflect ultra violet light or certain light colors from the moon. The moths recognize the reflected light as a food source. That means the light may be the way the recognize food; it is difficult for them to distinguish the light from a bulb from that of a plant. Others may be active at night to avoid predators. If you are to look under leaves at night, you will find some moths who prefer daylight waiting for the sun to return so they can find food.

For a science fair project you may want to set out different types of light to see which light attracts which kind of insect. Try a standard household light as a control. Then use a blue light, a yellow light, and a red light. Place them far enough apart so insects will be able to choose which they like. Observe the insects that are attracted to each and compare your results.

Moths that are attracted to artificial light may be on a disaster path. Bug zappers use light to kill insects, car lights attract insects, lights that attract insects bring them close to humans armed with insecticides. This is all disastrous to an insect.

These are some websites you may want to visit.

http://insects.ummz.lsa.umich.edu/MES/notes/entnotes7.html
http://gears.tucson.ars.ag.gov/gears/nx/night-shift/night-shift.html
http://www.umassd.edu/specialprograms/lloyd/leps.html