The battle against summer is most aggravating insect has hit an all-new, high-tech level. Raiding your world of mosquitos with magnets or vacuums may be costly but man is it worth it, writes June Fletcher in The Wall Street Journal.

As soon as visitors arrive at Alex Randall’s Caribbean hideaway, he hands them small yellow racquets. But they aren’t for tennis. They’re battery-operated bug zappers with electrified “strings,” used to whack the clouds of mosquitoes that infest his 1-acre home near St. Thomas. “If you accidentally hit yourself — youch!” says Mr. Randall, a radio announcer.

Forget the citronella candles and the flyswatter — this summer the war against mosquitoes has gone high-tech. From bug vacuums that look like laser swords to wristwatches that mimic the sound of a dragonfly’s wings, gadget makers have been rolling out the heavy artillery. Perhaps the hottest thing on the market: an $800 propane-powered gizmo called the Mosquito Magnet that supposedly emits the smell of animal breath to attract bugs. While spending on repellents is up a moderate 5.4% this year to $112.4 million, gadget makers are reporting big increases: Lentek, maker of the bug vac, for instance, says sales have quadrupled over the same period last year.

Of course, the battle of the bugs isn’t a new one. But it’s gotten so high-tech — and so expensive — for a simple reason: fear. The outbreak of the mosquito-borne West Nile virus two years ago spurred emergency spraying campaigns in the New York area. In Houston this year, in the wake of Tropical Storm Allison, as many as 100 of the bloodsuckers were landing on people per minute — raising the specter of encephalitis and other viral epidemics. Add in the wet spring in many parts of the country, which had mosquito levels at record numbers — one St. Louis park known locally as Vampire Hollow had bug counts in late June four times their usual level — and you’ve got the makings of a real scare.

Almost universally, mosquito experts say this is a classic case of overreaction. “People are panicking, looking for new things,” says Dan Kline, a U.S. government entomologist who gets 50 e-mails a day — up from that many a week — from mosquito-plagued homeowners. Most of the high-tech artillery is unnecessary, says Ulrich Bernier, a federal entomologist in Gainesville, Fla. In the U.S., he says, “mosquitoes are more of a nuisance than a real threat of disease.”

Try telling that to Tim and Bilynda Muldoon, whose mosquito-infested Harvard, Mass., yard was so bad “we couldn’t even go outside,” Mrs. Muldoon says. They tried everything — citronella candles and bracelets, even one of the devices that mimics the sound of dragonfly wings — before finally shelling out $1,300 for a “professional” model Mosquito Magnet. By the third week, when they checked the trap, they found hundreds of tiny winged corpses. And, after investing in a second magnet, they were able to go outside again. “We still get a bite or two,” Mrs. Muldoon says. “But at least I’m not the only mosquito magnet around.”

As far as most people are concerned, bug technology reached its high point with those black-light bug zappers whose zzzz … pop! has punctuated many a backyard cocktail party. But in the past few years, the bug-fighting industry has gone into overdrive. Some of its biggest sellers are refashioned older products: The chemical that’s used in smoky mosquito coils has been repackaged as the OFF! Mosquito Lamp ($9), Lentek’s $15 Tomb or Schwabel’s ThermaCELL Mosquito Repellent ($25). Then there’s S.C. Johnson & Son’s OFF!, which now comes in a goopy, soapy-scented purple “Magicolor” version. Even those bug zappers have been updated — these days, rather than frying mosquitoes, which explodes germs into the air, they drown them in water.

Dustbusters for Bugs

Also on the market: mosquito bracelets (some contain repellents, others use sound), mosquito vacuums (like Dustbusters for bugs) and Alex Randall’s racquets. At the top of the tech heap, is the Mosquito Magnet, which works by converting propane into a plume of carbon dioxide, heat and humidity that draws bugs, which then get sucked into a net inside the machine. Ray Iannetta, president of American Biophysics Corp., the East Greenwich, R.I., maker of the Magnet, says one reason his unit is so expensive is it uses 11 ounces of platinum to drive the chemical reaction.

@page_break@Mary Haley, a Vienna, Va., homemaker, is sold on the new technology. Every time she goes out, she wears a $6 lime-green plastic wristband from BugOff! whose active ingredients are that old-standby citronella, plus geraniol (a newly discovered compound that seems to make wearers invisible to mosquitoes) and lemongrass. That keeps her arms bite-free, but not her face. “As silly as it looks, I wish I could wear it around my neck,” she says.

And after various commercial repellents — as well as home remedies such as garlic and vinegar — failed to ward off the bugs on Terry Lee’s back deck, she started relying on a flyswatter powered by her husband. But then he got sick of being the family bug-killer. “My husband said if I asked him to swat one more bug, he’d swat me,” says Mrs. Lee, a retired nurse in Los Angeles. Now she swears by a $50 Bug Vacuum whenever she sits out — “it’s my magic wand,” Mrs. Lee says.

But is any of this really worth it? Mr. Bernier, the Florida entomologist, says the effectiveness of any product may depend on where you live — different mosquitoes may be more or less susceptible to different repellents and attractants. What they aren’t susceptible to, says Harold Harlan, senior entomologist at the National Pest Management Association, an industry group, are gadgets that emit electrical pulses, magnetic fields or sound, because all mosquitoes really care about is scent.

Lou Lentine, president of Lentek, maker of many such gadgets, says that the company does its own testing and that the products work. However, one outside group found in its tests that some electronic products reduced the bugs by only 35%, a “not significant” effect. “Wouldn’t you call a 35% reduction in your salary significant?” Mr. Lentine counters.

Flying From Miles Away

Meanwhile, the pricey Mosquito Magnet gets high marks from bug experts, but even it has a downside: It may be too effective, attracting mosquitoes from miles away. “If they get to you first, you’re dinner,” Mr. Harlan says. Mr. Kline, the government mosquito expert, has come up with his own low-tech version of the magnet: dirty socks (the smell is apparently nectar to mosquitoes) hung over a tank of carbon dioxide. “The neighbors looked at me strangely,” Mr. Kline says. “But the mosquitoes really love that good foot odor.”

Some people find even that a little too much. Leonard Ladin, a retired chemist, eschews chemicals as “too dangerous,” and calls the various bug zappers he’s tried “hopeless.” Mr. Ladin’s solution? A hat covered with mosquito netting that ties under his chin, which he wears with long-sleeved shirts, pants and gardening gloves while puttering around the 28 flower beds on his Copake, N.Y., estate. “People laugh, but I never get bitten anymore,” he says.