Urban Pest News
Electric Insect Traps Get Good Bugs, Miss Mosquitoes
Homeowners often buy fancy electric insect traps to keep the mosquitoes and other biting
flies at bay. The snap, crackle and pop of fried arthropods seems to confirm their effectiveness,
but are these traps really doing much good? The traps in question use ultraviolet light to lure in
flying insects, but many species of mosquitoes are not attracted to light. However, many other
nontarget insects are attracted to lights and are inadvertently destroyed.
Researchers in Delaware tracked the insects caught in the electric traps of six homeowners in
suburban Newark on a weekly basis throughout the summer. All the homes were in or near
lowland, wooded sites rich in aquatic breeding habitats, so they were close to lots of mosquitoes
Of the 13,789 insects counted, only 31 were biting flies (a mere 0.22%!). Nearly half of
the insects collected were nonbiting aquatic insects such as caddisflies and midges. More
importantly, 1,868 predators and parasites (13.5%) were destroyed within 27 families of
predators and nine families of parasitoids. Ground beetles, rove beetles, and braconid wasps were
particularly common vicitms.
By their calculations, 71 to 350 billion nontarget insects are needlessly destroyed in the
U.S. each year by misinformed homeowners, without any real control of nuisance insects. The
heavy toll on nontarget insects, including beneficial insects, suggests that electrified traps may
actually be counterproductive for insect control.
Frick, T. B. and D. W. Tallamy. 1996. Density and diversity of nontarget insects killed by suburban electric
insect traps. Ent. News 107(2): 77-82.
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