Electric bug zappers have been around a lot longer than you might think -- the first was patented back in 1934. Commercially, they're very successful and have even spawned handheld variants like The Executioner. But scientifically speaking, they're not so hot. Studies show that, on average, only a tiny percentage of bugs killed by the average backyard zapper are pests. Meanwhile, billions of harmless or even beneficial insects are killed by zappers each summer.