This one may have gotten started with a study in which bats were released into a room full of bats while researchers counted how many they ate. The bats consumed about 10 per minute, or 600 per hour. But mosquitoes were the only insects in the room for the hungry bats to eat. Since then, studies have found that mosquitoes make up less than 1 percent of bat diets.

While zappers do kill a large number of insects, studies have found that most of them are moths and beetles, and less than 7 percents are mosquitoes. In fact, yards with zappers typically have no fewer mosquitoes than yards without zappers.

Researchers have consistently found that these devices have absolutely no effect on mosquitoes at all. They don't repel, attract or in any way change mosquito behavior or effect the number in a given area.

Several other household items are also supposed to be repellents, including banana peels and Vicks VapoRub. But repeated studies have shown that DEET is the only one that is consistently effective in blocking mosquito bites over extended periods of time. While picaridin and oil of lemon eucalyptus also been shown to repel mosquitoes, neither provides the same level of protection as DEET.