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An experiment to reduce the mosquito population
An experiment to reduce the mosquito populati... 06:08

The deadliest animal on Earth is not the shark, or the snake, or the scorpion, or even us. It's the mosquito. The diseases they carry kill over a million people a year, and in a warming climate they're spreading to new places.

In 2013, a particularly nasty species arrived in Fresno, California: aedes aegypti

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The aedes aegypti mosquito, which can transmit Zika, dengue and other viruses.  CBS News

"She's evil," said Jodi Holeman, who works for Fresno's mosquito-control department. "This is a female that will bite you multiple times. She's very, very aggressive. The one thing that you can say with great certainty is we don't have any very strong methods of control for this particular mosquito." 

Of course, spraying insecticide kills mosquitoes, but that kills other bugs, too. So, how do you solve a problem like aegypti? 

That's where Verily comes in. 

After nine years at Google, working on its Chrome web browser, Linus Upson wanted a bigger challenge – and Verily, a Google sister company, was willing to fund his experiment. "What I wanted to do was a variation on something called the Sterile Insect Technique," he told correspondent David Pogue. "If a sterile male mates with a fertile female, she'll still produce and lay eggs, but they won't hatch. Each generation gets smaller and smaller. And you can actually completely remove mosquitoes from an area."

So, Upson hatched a plan: Build a factory that churns out millions of special male mosquitoes, each carrying a harmless natural bacteria that makes him incapable of reproducing. Release those males to mate with the wild females (with the EPA's blessing, of course!), and presto! The mosquito population plummets.

In theory. 

Pete Massaro, Google's director of automation, gave "Sunday Morning" a rare tour of Massaro's Marvelous Male Mosquito-Making Machinery, which takes bags filled with food and L1 larvae and puts them onto trays. "Those are gonna then enter into the larval rearing robot," Massaro said. 

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Trays of mosquito larvae are developed.  CBS News

For the next six days, this robot will keep the mosquitoes warm, feed them, and keep them company.  The next step is to separate the boys from the girls using a glorified sieve. "The females are slightly bigger than the males," Massaro said. "We're able to separate 97% to 99% of the males and females."

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Manufacturing mosquitoes.  CBS News

But 99% isn't good enough! Releasing any females might make the problem worse. So, this incredible machine photographs each bug, studies the picture to determine the sex, and then blows away the females.  

"And that works?" Pogue asked.  

"That has worked so incredibly well that, you know, to our knowledge, no females have ever left this factory," Massaro replied.

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Cameras determine the sex of mosquitoes. Females are eliminated.  CBS News

Finally, vans release the sterile males into the wild. 

Senior scientist Jacob Crawford was in charge of measuring the results: "I very clearly remember a huge drop in the hatch rate," he said. "I stood up and did a dance! I mean, that was our first field data showing that this could work. This could really work." 

It really did work. "We got over 95% suppression of the wild population," Upson said. "And we hope to make it even more effective still, by releasing over larger areas for longer periods of time."

The project, Debug Fresno, ran for three summers – 2017, '18, and '19 – and that was it. It was a three-summer prototype to (ahem) work out the bugs. And the problem with the Sterile Insect Technique is that if you don't keep releasing the modified males, the mosquito population bounces right back. 

Holeman said, "In 2020, sure enough, those traps started to light up again. Those were heartbreaking conversations to have: 'I'm sorry, I know we had this really great effective program, but it can't come back'!"

But the Fresno test proved that Linus Upson's idea really works – without chemicals, genetic engineering, or affecting any other species. 

Verily is now setting up the program in places where mosquitoes actually kill people, like Puerto Rico and Singapore.

Of course, Verily is a Silicon Valley tech company. It's not doing all of this for free.  

"The goal," Upson said, "is to make this a sustainable business."

The pitch to governments: We'll get rid of your mosquitoes for less than you're spending on the diseases they spread.

It's been a strange, satisfying second act in Linus Upson's career. 

Pogue said, "I mean, it's not a web browser, right? It's nature. It's not all within your control."

"Different kinda bugs we're dealing with!" Upson laughed.


For more on the mosquito experiment, and other tantalizing scientific stories, tune in to David Pogue's new podcast, "Unsung Science," in which every week he will bring you the behind-the-scenes creation story of a breakthrough in science or tech, from the characters who did the breaking through. Available wherever you download your podcasts. From CBS News and Simon & Schuster.

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CBS News/Simon & Schuster

      
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Story produced by Gabriel Falcon. Editor: Joseph Frandino. 

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