Myths of Mosquito Control

Bug Zappers

Electrocuting devices, also known as bug zappers, rely on ultraviolet light to draw insects through an electrified wire grid. Studies show that bug zappers do not reduce the number of biting mosquitoes. One concern is the high number of non-pest insects such as beetles and moths that are killed by these devices. Some of these insects are beneficial as a natural biological control against mosquitoes and other pests. The continued popularity of these traps is most likely due to the never-ending sound effects, which remind owners that their investment is working, but not necessarily against mosquitoes.

An article in Entomological News (107(2): 77-82), a publication of the American Entomological Society, states: "Our survey of insects electrocuted during routine use of electric insect traps revealed only 31 biting flies, a minute proportion (0.22%) of the 13,789 total insects counted... The heavy toll on non-target insects and the near absence of biting flies in catches suggests that electric insect traps are worthless for biting fly reduction -- and probably are counterproductive -- to homeowners and other consumers."

Ultrasonic Devices

Hand-held electronic devices that rely on high frequency sound to repel mosquitoes have become surprisingly popular. Some claim to mimic the wing beat frequency of a male mosquito. Others claim they mimic the sound of a dragonfly, causing mosquitoes to flee the area to avoid becoming the predator's next meal.

Most of the ultrasonic devices on the market hum on a single frequency. Scientific studies have repeatedly shown that electronic mosquito repellers do not prevent host seeking mosquitoes from biting. Mated females mosquitoes do not flee from infatuated males, and mosquitoes do not vacate an area hunted by dragonflies. Ultrasonic repellers do little in the way of reducing mosquito annoyance. Review the research

Bats and Bat Houses

Bats feed on the same insects that turn up in bug zappers and are no more effective for controlling mosquitoes than their electronic equivalent. Bats feed primarily on beetles, wasps, ants, flies, stoneflies, mayflies, moths, and grasshoppers. Mosquitoes consits of less than 1% of a bat's diet.

The evidence from stomach analysis and feces examinations show that bats who prey on insects do help regulate insect populations, but not mosquitoes. Providing habitat to enhance bat populations is an admirable activity for conservation purposes. Using mosquito control as the reason to initiate public interest is misleading at best. Review the research

Purple Martins

Purple martins are wonderful birds and having a colony nearby is educational and aesthetic. Martins, like all swallows, are aerial insectivores. They eat only flying insects, which they catch in flight. Their diet is diverse, including dragonflies, damselflies, flies, midges, mayflies, stinkbugs, leafhoppers, Japanese beetles, June bugs, butterflies, moths, grasshoppers, cicadas, bees, wasps, flying ants, and ballooning spiders.

Martins are not, however, prodigious consumers of mosquitoes as is so often claimed by companies that manufacture martin housing. An intensive 3-year diet study conducted at Purple Martin Conservation Association headquarters in Edinboro, PA, failed to find a single mosquito among the 350 diet samples collected from parent martins bringing beakfuls of insects to their young. The samples were collected from martins during all hours of the day, all season long, and in numerous habitats, including mosquito-infested ones.

Purple Martins and freshwater mosquitoes rarely ever cross paths. Martins are daytime feeders, and feed high in the sky; mosquitoes, on the other hand, stay low in damp places during daylight hours, or only come out at night. Since Purple Martins feed only on flying insects, they are extremely vulnerable to starvation during extended periods of cool and/or rainy weather. Review the research

For more information about Purple Martins and WNV, click here.

Citronella Candles

Citronella is the active ingredient commonly found in natural or herbal insect repellents marketed in the United States. Studies show that citronella candles can be useful as a repellent, but they provide shorter protection time than most mosquito repellents containing DEET. When near the candle, it will provide more protection than if no precaution measures are taken. However, citronella plants provide no protection from biting mosquitoes. Review the research

Plant-Derived Repellents

Thousands of plants have been tested as potential sources of insect repellents. However, none of the plant-derived chemicals tested to date demonstrate the broad effectiveness of DEET.

A few plants whose essential oils have been reported to have insect repellent activitiy (not all include mosquito repellent activity) include: citronella, cedar, verbena, pennyroyal, geranium, lavender, pine, cajeput, cinnamon, rosemary, basil, thyme, allspice, garlic, and peppermint. Unlike synthetic insect repellents, plant-derived repellents have been poorly studied. When tested, most of these essential oils tended to give short-lasting protection. Review the research