TECHNOLOGY.... TODAY ,TOMMORROW.....

   After sunset, just turn on your porch light and soon you will be treated to a hundreds of, thousands of bugs. And more interestingly frogs and other predators takes advantage of their easy catchings.... But always remember not all insects get attracted to those impulses. Unfortunately this is a cruel trick played by our innovation moving faster than their evolution.
   A well accepted theory about this is that some insects use these light source as a navigational aid. Consider the example below:
An insect flying towards north, for its navigation may keep sun or moon as a reference source as far as the source of light remain constant  and at a distance. However the insect get confused with the source of radiation from an incandescent bulb in the porch as the flies the light to be at either of its sides for navigation.
   Actually the phenomenon which explains why some insects are attracted towards light and why some show repulsion is  "Photoaxis". This photoaxis can be of two types; positive and negative. Some insects like cockroaches or earthworm show repulsion and hence have negative photoaxis while others like moth,flies have positive photoaxis. Some scientists also argue that these flies are not attracted towards the light but the darker regions surrounding the light source, that is why insects are attracted towards artificial light even if the natural light becomes available.