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Floral-Scented Pesticide Lures Mosquitoes to Their Death

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There are those who argue that mosquitoes serve a purpose, that their droning, blood-gorging presence represents an important link in a fragile food chain. Then there's Agenor Mafra-Neto, who mostly just wants them to die. The chemical ecologist and his colleagues presented their new strategy for mosquito control at the 254th National Meeting & Exposition of the American Chemical Society.

Irritating though they are, mosquitoes are much more than just pests; they're also vectors of deadly diseases that claim millions of lives every year. While some scientists race to develop and administer vaccines against these viruses, others are tackling the problem from the other end, hoping to block the bloodsuckers before they ever pierce a person's skin.

Today's most common chemical mosquito-protection measures are effective, but nonspecific. The same insecticide that takes out a mosquito can kill a bee or poison a dog or a baby. Pesticide runoff can contaminate the water supply. It also can't eliminate all the mosquitoes, and the survivors reproduce, thereby increasing their resistance to the chemicals.

In other words: There's room for improvement. So Mafra-Neto, founder of the pest management laboratory ISCA Technologies, teamed up with researchers from other universities to create something better.

First, they gathered piles of mosquitoes' favorite nectar-producing plants and analyzed the chemical makeup of each flower's fragrance. They exposed mosquitoes to individual elements of each fragrance to find out which ones got their attention, then eliminated any scent that also brought bees to the yard. The final result was an intoxicating perfume of sugars and proteins that no mosquito could refuse.

The researchers mixed this special blend with a highly concentrated, slow-release pesticide called Vectrax, which can be sprayed or spread onto plants and buildings. The pesticide solidifies in teeny droplets and will not spread to other surfaces, but it will spread in the bodies of the mosquitoes who come to taste it.

And taste it they do.

"The blend of chemicals that we use to attract mosquitoes is so powerful that they will ignore natural plant odors and attractants in order to get to our formulation," Mafra-Neto said in a statement. "From a mosquito's point of view, it's like having an irresistible chocolate shop on every corner. The product is so seductive that they will feed on it almost exclusively, even when it contains lethal doses of insecticide."

Mafra-Neto and his colleagues are currently conducting field tests in malaria-vulnerable villages of Tanzania. Their early results suggest that their product can cut mosquito populations by two-thirds in the first two weeks alone, and may be able to eliminate the pests entirely. Mafra-Neto wouldn't be sorry to see them go.

"I truly hate mosquitoes and ticks," he says. "Imagine: Maybe one day we will be able to go into our backyards or parks and not have to worry about being bothered by either of them."

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The Surprising Reason Why Pen Caps Have Tiny Holes at the Top
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If you’re an avid pen chewer, or even just a diehard fan of writing by hand, you’re probably well acquainted with the small hole that tops off most ballpoint pen caps, particularly those classic Bic Cristal pens. The reason it’s there has nothing to do with pen function, it turns out. As Science Alert recently reported, it’s actually designed to counter human carelessness.

Though it’s arguably unwise—not to mention unhygienic—to chomp or suck on a plastic pen cap all day, plenty of people do it, especially kids. And inevitably, that means some people end up swallowing their pen caps. Companies like Bic know this well—so they make pen caps that won’t impede breathing if they’re accidentally swallowed.

This isn’t only a Bic requirement, though the company’s Cristal pens do have particularly obvious holes. The International Organization for Standardization, a federation that sets industrial standards for 161 countries, requires it. ISO 11540 specifies that if pens must have caps, they should be designed to reduce the risk of asphyxiation if they’re swallowed.

It applies to writing instruments “which in normal or foreseeable circumstances are likely to be used by children up to the age of 14 years.” Fancy fountain pens and other writing instruments that are clearly designed for adult use don’t need to have holes in them, nor do caps that are large enough that you can’t swallow them. Any pen that could conceivably make its way into the hands of a child needs to have an air hole in the cap that provides a minimum flow of 8 liters (about 2 gallons) of air per minute, according to the standard [PDF].

Pen cap inhalation is a real danger, albeit a rare one, especially for primary school kids. A 2012 study [PDF] reported that pen caps account for somewhere between 3 and 8 percent of “foreign body aspiration,” the official term for inhaling something you’re not supposed to. Another study found that of 1280 kids (ages 6 to 14) treated between 1997 and 2007 for foreign body inhalation in Beijing, 34 had inhaled pen caps.

But the standards help keep kids alive. In that Beijing study, none of the 34 kids died, and the caps were successfully removed by doctors. That wasn’t always the case. In the UK, nine children asphyxiated due to swallowing pen caps between 1970 and 1984. After the UK adopted the international standard for air holes in pen caps, the number of deaths dropped precipitously [PDF]. Unfortunately, it’s not foolproof; in 2007, a 13-year-old in the UK died after accidentally swallowing his pen cap.

Even if you can still breathe through that little air hole, getting a smooth plastic pen cap out of your throat is no easy task for doctors. The graspers they normally use to take foreign bodies out of airways don’t always work, as that 2012 case report found, and hospitals sometimes have to employ different tools to get the stubbornly slippery caps out (in that study, they used a catheter that could work through the hole in the cap, then inflated a small balloon at the end of the catheter to pull the cap out). The procedure doesn’t exactly sound pleasant. So maybe resist the urge to put your pen cap in your mouth.

[h/t Science Alert]

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Big Questions
What Causes Sinkholes?
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Mark Ralston/AFP/Getty Images

This week, a sinkhole opened up on the White House lawn—likely the result of excess rainfall on the "legitimate swamp" surrounding the storied building, a geologist told The New York Times. While the event had some suggesting we call for Buffy's help, sinkholes are pretty common. In the past few days alone, cavernous maws in the earth have appeared in Maryland, North Carolina, Tennessee, and of course Florida, home to more sinkholes than any other state.

Sinkholes have gulped down suburban homes, cars, and entire fields in the past. How does the ground just open up like that?

Sinkholes are a simple matter of cause and effect. Urban sinkholes may be directly traced to underground water main breaks or collapsed sewer pipelines, into which city sidewalks crumple in the absence of any structural support. In more rural areas, such catastrophes might be attributed to abandoned mine shafts or salt caverns that can't take the weight anymore. These types of sinkholes are heavily influenced by human action, but most sinkholes are unpredictable, inevitable natural occurrences.

Florida is so prone to sinkholes because it has the misfortune of being built upon a foundation of limestone—solid rock, but the kind that is easily dissolved by acidic rain or groundwater. The karst process, in which the mildly acidic water wears away at fractures in the limestone, leaves empty space where there used to be stone, and even the residue is washed away. Any loose soil, grass, or—for example—luxury condominiums perched atop the hole in the ground aren't left with much support. Just as a house built on a weak foundation is more likely to collapse, the same is true of the ground itself. Gravity eventually takes its toll, aided by natural erosion, and so the hole begins to sink.

About 10 percent of the world's landscape is composed of karst regions. Despite being common, sinkholes' unforeseeable nature serves as proof that the ground beneath our feet may not be as solid as we think.

A version of this story originally ran in 2014.

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