Types

• Most of the bugs drawn to porch lights are moths of one type or another, but you may sometimes see other bugs around lights. Light does not normally attract pests, including biting insects, according to the O. Orkin Insect Zoo. That is why bug zappers kill more harmless bugs than pests.
  
  

Theories/Speculation

• Entomologists believe that some bugs navigate by the moon. They keep a certain angle between themselves and the light source. Porch lights confuse bugs because they provide an unknown source of light.
  
  

Trapping

• If you want to collect bugs, you can exploit their attraction to light. Hanging a white piece of cloth outside near a porch light invites bugs to land, so you can collect them off the piece of cloth.