What Happened to the Mosquitoes in Fresno?

Season 1 • Episode 1

Mosquitoes are the deadliest creatures on earth; they kill 500,000 people a year—and as the planet warms, more species are spreading North from the tropics. In 2013, a nasty new type, called Aedes Aegypti, arrived in Fresno, California. But traditional tactics, like spraying insecticide and genetic modification, have ugly side effects. So one genius programmer from Google thought up a better solution—that doesn’t involve insecticide; doesn’t mess around with genes; doesn’t require irradiating; makes it impossible for the mosquitoes to develop resistance; can’t affect any other species; and costs less than what governments spend now on treating their citizens for Dengue fever. A lot was at stake in the Fresno experiment; if it worked, the technique could save lives around the world. (Spoiler: It worked.) 

Guests: Linus Upson, VP of Engineering at Verily. Leslie Vosshall, professor of neuroscience at Rockefeller University. Jodi Holeman, Fresno Consolidated Mosquito Abatement District. Peter Massaro, Google director of automation. Jacob Crawford, senior scientist, Verily.

Episode transcript

Unsung Science 1.1—The Mosquitoes of Fresno

Theme begins.

In 2013, Fresno, California, was invaded. The conqueror’s name: Aedes aegypti. 

Jodi: It is, like, the nastiest mosquito that’s out there. So it’s — it’s like the perfect evil species, really. 

You can spray insecticide, but that also kills bees and butterflies. You can try genetic engineering, but you run the risk of the mosquitoes developing resistance.

But now, there’s a third option—no chemicals, no genetic shenanigans. And it was dreamed up…by a software engineer at Google.

I’m David Pogue—and this is “Unsung Science.”


Hey there! I’m David Pogue, and this is Unsung Science: the stories behind amazing accomplishments in science and tech. 

Season 1, Episode 1…get psyched! 

The deadliest animals on earth are not snakes, scorpions, sharks, or even other people. It’s mosquitoes. They kill a million people every year—by biting us and infecting us with fun stuff like malaria, dengue fever, yellow fever, zika, West Nile, chikungunya, and so on.

You probably associate most of those afflictions with faraway, tropical climates. And that used to be a good assumption. But nowadays, in the climate-changed climate? Not so much.

Vosshall: So the milder the winters, the more favorable the neighborhood is for mosquitoes. It’s like a new housing development that’s opening, like, “Now building phase three!” Right? That’s going to just keep moving up the Eastern Seaboard, because they need to not have overly harsh winters to be able to survive. 

This is Leslie Vosshall, a professor of neuroscience at Rockefeller University. In 2015, she was elected to the National Academy of Sciences, which is a big deal. I know this, because she’s my sister-in-law.

Pogue: Sorry not to have had our annual holiday get together. 

Vosshall: I miss it. I was I was so ready for it. It’s the highlight of our year. 

For the last decade, Dr. Vosshall—oh man, so weird to call her that—Leslie—has been studying mosquitoes: how they find us and why they bite us. So before I tell you why you should care about Fresno’s mosquito problem, I’m going to let her blow your mind with three mosquito facts. 

Fact #1: Only the females bite. 

Leslie: Yeah, this is an important point. And I’m amazed that 99 percent of both the general public and Ph.D. scientists find that surprising. Most people assume that a mosquito is a mosquito, that the females and the males are both equal-opportunity blood feeders. Only females bite. 

Which is going to be very important as this story unwinds. 

Ok, Fact #2: Those little ladies don’t mean us any harm. 

Leslie They’re not doing it on purpose. They’re not doing it because they hate people and they want to kill them. The females are going about their mandate. Their mandate is to get blood. That is their one job as future mothers, is to get blood. Because without that blood, she won’t produce children. 

They’re not even the original source of the diseases:

Leslie: (cont’d) So humans just happen to be carrying these diseases, and the females spread them. In the process of eating their meal from us, they end up infecting people. 

And fact #3 is the one that fried my brain. In the warmer climate, mosquitoes are spreading northward into new regions—but not by flapping their little wings.

Leslie: They don’t really move around by their own power. They’ll move around maybe a half a mile. But it’s people that move them, absolutely you’re right about that.

That’s right: We are spreading the mosquitoes. 

Leslie: The two biggest ways that mosquitoes hitchhike around the world, those stupid floral arrangements that you get, those little bamboo things, those little sprouted bamboo things that are filled with water—where are they set up? They’re set up in the tropics. So they come from China, Thailand, Vietnam. Somebody sets them up, puts them on some big container ship and puts them into flower shops all over the country. And those things tend to be full of mosquitoes. 

The other major way that the animals hitchhike is on the global used tire trade. So, tires are heaven for mosquitoes. If you want to set up a mansion for mosquitoes, tires! Because they’re black, they end up heating up, and they are they filled with water, which just becomes like a teeming nursery for mosquitoes. 

Leslie Vosshall spends most of her time studying one mosquito species in particular: Aedes aegypti. Two Latin words: Aedes, A-E-D-E-S, and aegypti, spelled like A-Egypt-I. It’s the worst.

Jodi: Yeah, it’s probably, you know, top two most wanted mosquito in the queue. You could arguably top—most wanted mosquito in the mosquito world. So, yeah, it’s not the one that you want to be dealing with. 

Jodi Holeman is the superintendent of operations for the Consolidated Mosquito Abatement District in California—that’s Fresno and nearby Central Valley towns. She’s quiiiiite familiar with Aedes aegypti. 

Jodi: It is, like, the nastiest mosquito that’s out there. It’s super aggressive with people, difficult to find, difficult to control. A single female will bite you multiple times. I can’t tell you how many residents have shown me their legs, their arms, their extremities, and all the bites that they have. So it’s — it’s like the perfect evil species, really. 

Until a few years ago, Aedes aegypti was the rest of the world’s problem. But in 2013, as part of its master plan to move north, aegypti arrived in Fresno, California. 

Mercifully, the Fresno aegyptis are not carrying diseases, as they do in other parts of the world—at least not yet. But they are incredibly annoying. 

Jodi: People are not used to it. People in our jurisdiction in the Central Valley of California, they associate really bad mosquito problems with camping, or going up into high elevations—not going into their backyards, right? So now we have this new species that’s super aggressive. 

Now, we’re not completely helpless. We do have some anti-mosquito artillery at our disposal. For example, we can spray insecticides—and we do. A lot. 

Unfortunately, insecticides kill more than mosquitoes. They also wipe out lots of innocent-bystander bugs—like honeybees, ladybugs, and butterflies—some of which actually would have helped with the mosquito problem, if, you know, we hadn’t killed them. 

Insecticides also accumulate in the water, which kills frogs and fish, and eventually makes its way into our bodies.

And worst of all, over time, mosquitoes develop resistance to our insecticides, exactly the way certain bacteria become resistant to our antibiotics. The world’s chemical companies have to keep tinkering with the formulas so their sprays remain effective.

There are also ways to reduce the mosquito population through genetic engineering, using CRISPR gene-editing techniques. But according to Leslie, that approach has its own problems, one of which is, again, resistance.

Leslie: Once you start CRISPRing mosquitoes, I do have the concerns about, like, what is the long term strategy for having that not get you resistance in a couple of years? I think even already in the laboratory, it doesn’t take that long for mutations to arise, where the female will circumvent —the population will circumvent that. 

The other problem with genetic modification is that it involves the words “genetic modification.” Which terrifies a lot of people. You know, playing God, tinkering with nature’s delicate balance, all that kind of thing.

Leslie: People are at this unprecedented state where nobody trusts scientists. There has to be an enormous amount of public engagement. You have to convince the public that it is safe.

Out in California, Jodi Holeman’s team had tried everything to solve the mosquito problem in Fresno. Spraying. Educating people about standing water in their yards. Nothing worked.

Jodi: Even with literally throwing every tool we had in the toolbox at this particular species when we first identified it in our district, it continued to spread. It was a—pretty colossal failure. 

OK. So how do you solve a problem like aegypti?

With Silicon Valley software engineers, of course. You’ve probably heard that cliché about how they just want to make the world a better place—but sometimes, they actually do it. 

Linus: After working at Google a number of years, I managed to get the freedom to have, to go try crazy things. And I was able to get permission to go and try this crazy thing. 

Linus Upson no longer works at Google. Now he works at Verily Life Sciences, Google’s sister company—part of the Alphabet family. Verily is dedicated to solving public-health problems.

Linus: (cont’d) And at the beginning, I gave ourselves maybe a 20 percent chance of success. There’s a lot of things in biology and in health care that fail. It’s much less reliable than computer science. But I thought the payoff was big enough in terms of the impact you could have on global health, that it was worth trying. 

That payoff would be wiping out mosquito-borne diseases by drastically reducing the mosquito population. But not by spraying, and not with genetic tampering.

His big idea—the one he gave a 1 in 5 chance of success—was the sterile insect technique, or S.I.T. 

I hope you’re sitting down.

Linus: So the sterile insect technique was developed by a couple of very clever entomologists. If a sterile male mates with a fertile female, she’ll still get the insect equivalent of pregnant. She’ll still produce and lay eggs, but the eggs won’t hatch. You can make each generation smaller and smaller. 

The sterile insect technique debuted in the 1950s, when it was used to tackle the New World Screwworm Fly, a nasty little parasite that was killing thousands upon thousands of cattle, and costing ranchers billions of dollars.

Linus: They chew their way through the animal, killing and maiming it in the process. And this was costing cattle ranchers billions of dollars. 

And so they reared billions and billions of screwworm fly, dropped them from airplanes across the United States, and over a 10 year period, completely removed screwworm fly from the United States. 

So here, at last, is the big reveal: Linus Upson’s master plan. 

His mosquito-control idea doesn’t involve insecticides; doesn’t mess around with genes; doesn’t require irradiating the males; making it impossible for the mosquitoes to develop resistance; can’t affect any other species; and costs less than what governments spend now on treating their citizens for Dengue fever.

The experts rave. Jodi Holeman, Consolidated Mosquito Abatement District:  

Jodi A beautiful system. It really is. 

Leslie Vosshall, Rockefeller University: 

Leslie: Very clever, very effective, kind of more cost effective because they don’t have to deal with a few animals escaping, still being fertile.So I think that that’s highly effective. 

The key to the whole thing is another Latin-named critter: Wolbachia.

Linus: Instead of irradiating the mosquitoes to make them sterile, we actually take advantage of a naturally occurring bacterium that exists in more than half of the world’s insects, called Wolbachia. 

That’s W-O-L, b-a-c-h, I-A. Wolbachia. A very common, very widespread, harmless kind of bacteria. It’s found naturally in 60% of all insect species—but not Aedes aegypti. 

And here’s a lucky break: If a male mosquito does get Wolbachia, it can go right ahead and have sex with a female in the wild that doesn’t have Wolbachia. She’ll lay her eggs—but they’ll never hatch. 

Linus: And if the male has Wolbachia and the female doesn’t, she’ll still produce and lay eggs. But the Wolbachia will arrange for those eggs to die. 

David: Wow! So the male doesn’t know that anything’s wrong, the female doesn’t know that anything is wrong. She—she goes ahead and lays her eggs. It’s just that the next generation doesn’t come along. 

Linus: That’s right. 

It sounded very cool in principle. All he had to do to get started… was build the world’s largest, airlock-controlled, robotically governed mosquito-raising factory—and then invent a machine that could separate the boy mosquitoes from the girl mosquitoes without making a single mistake.

Last month, I got to see the place. After the break—I’ll take you on a tour.


Verily Life Sciences is dedicated to developing cool moon-shot human-health inventions like battery-powered, glucose-sensing contact lenses, or a spoon that holds steady even if you have a severe tremor. Its headquarters are a pair of huge, sleek, four-story office buildings in South San Francisco. 

If you pass through a courtyard, through security, and down a couple of hallways, you arrive at the mosquito-rearing facility. Our tour guide is Pete Massaro, Google’s director of automation. He designed a lot of the machines you’re about to meet.

The first stop… is the airlock. 

Peter: Remember—leave the mosquitoes in.

(airlock noise)

David: You have an airlock!? Oh wow.

(Leave the audio up, so that DP has to raise his voice.)

It’s just like the one on a spaceship, except here, they’re not worried about losing air to outer space; they’re—

(end of the blowing sounds—DP must compensate his volume)

—they’re worried about stray mosquitoes getting out of the building. Big fans blow air inward into the facility. 

Next, you enter… the insectary. 

Sound of the mosquitoes throughout:

It’s a plain white room, dominated by four gigantic mosquito cages, each a cube about four feet square. That sound you hear? That’s not fans. 

POGUE: I– I have to comment on the sound. (LAUGH) This is, like–

PETER: 600,000 mosquitoes flying sounds like– (LAUGH)

POGUE: A nightmare. (LAUGHTER)

PETER: It should make you itchy. 

It took me days to get that sound out of my brain.

Verily gets these mosquitoes, pre-infected with Wolbachia, from a company in Kentucky. Their eggs hatch into larvae, which look like minuscule white specks. They’re poured into clear plastic pouches, along with food and water, and loaded by robot into this—oh man, how can I describe it?

Begin robot audio

Imagine a grocery-store aisle, except that it’s only 2 feet wide. And the shelves on either side of you are made of stainless steel, and only a few inches tall each. So there’s like 35 shelves on each side. Each shelf contains those plastic bags full of developing mosquitoes. 

And running back and forth between the shelves is Pete Massaro’s masterpiece: a robot. An eight-foot-tall, faceless, shiny silver storage-and-retrieval robot. 

PETER: They’re now in here with the food and water. / 16:43:07  It’s also insectary conditions in there. So it’s 80 degrees. We feed those with that same robot– four times during the six days. 

All day long, the robot zooms back and forth through these skinny aisles, raising generation after generation of mosquitoes. It loads new trays into the shelves, tends them and gives them food pills, and then, after six days of growing, pulls the finished trays out.

The robot doesn’t have a name, but as far as those mosquitoes are concerned, it’s, “Mom.”

POGUE: And I see barcodes on those trays. Are you able to track these–

PETER: Every single– every location is tracked. Every mosquito has a name and a number. And every single mosquito has an image that’s stored on Google Drive.

POGUE: Its picture?

PETER: Every single one of ‘em. (LAUGH) Every one from the very first mosquito we ever made. 

POGUE: Have you ever thought about running the Department of Motor Vehicles? (LAUGHTER) It’s the same problem.

PETER: It would be fun. (LAUGH) 

After six days, the larvae have grown into pupae. At this stage, the females are slightly bigger than the males, which works out nicely for the next step: Separating the boys from the girls.

PETER: So in order to do the– sterile insect technique, using Wolbachia, you need to release only the males. So you wanna be very careful not to have females released. We have a very carefully designed sieve that separates about 97% to 99% of the females from males. 

Yes, a sieve. Yet another robot slices open each pouch and dumps its watery contents through a sieve. 

PETER: The males will– fall through the sieve. And females go to their destiny. Which is the municipal waste water treatment plant. (LAUGH) But actually– we actually, first we– we cook them. So that they’re not live.

And now comes… the really cool part.

The sieve is 99% accurate at separating the bugs by sex. But in this context, 99 percent isn’t good enough. If you release any Wolbachia females into the wild, they could wind up mating with your Wolbachia males, and the whole beautiful system of population control would fall apart. 

So how do you eliminate the last one percent of females? This is how Linus Upson explains it:

Linus We had to develop machines that can separate male and female mosquitoes at near perfection. 

David Come on. That sounds like a bad science fiction movie. How can you create a machine that separates male from female mosquitoes by the millions?

Linus There’s an engineer in our team who is an automation expert by training, named Victor Criswell. He spent about two and a half years trying to figure out how to get mosquitoes to march single file in front of a camera, so that we could take their picture and use jets of air to sort the males and females apart. Because the males and females actually look quite different from each other, if you can get a good picture of them. 

And these bugs just don’t want to do what you want them to do! If you want them to fly, they walk; if you want them to walk, they’re going to fly. If you want them to go one way, they’ll go the other way.

David: Was it ever in doubt that you’d be able to get these machines working? 

Linus: Oh, yeah! It was in doubt for about two and a half years! We tried dozens of different configurations, different ideas. Can we tell the difference between males and females by wing beat frequency? Do we want them flying? Do we want them walking? 

Yeah, it was lots and lots of things were tried before we were able to get to the point where we developed confidence of like, “OK, we don’t have it perfect yet, but we see a path where this could work.”

And believe it or not, it actually works. I witnessed it! The factory has over 150 of these sex-sorting machines, row after row of ‘em.

In each machine, you can see the mosquitoes walk one by one into a narrow, white, illuminated tunnel. A gate snaps shut behind it. That clicking you hear is all the little gates opening and closing.

PETER: It’s almost like ant trails or something. We don’t exactly know why they do this. They just get in there and walk right through. It’s, like, “Yeah, this is where I belong.” Right? 

Now, a camera takes the mosquito’s picture. Software identifies it as either male or female, and then clicks open one of two gates. A little puff of air blows the bug out of the tunnel.

PETER: And so if it’s a male, it will send it up into the container. If it’s a female or unidentified, it will send it to its doom.

POGUE: And– and that works?

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

POGUE: Well, Pete, would you go so far as to say that what is before us is the world’s most advanced mosquito sex-sorting machine?

PETER: I would definitely say that. (LAUGHTER) 

By the summer of 2017, the whole thing was ready to launch. The Verily team had worked out the bugs—sorry—and built themselves a rip-roaring, well-oiled mosquito factory, capable of churning out millions of males a week, every single one infected with Wolbachia bacteria. They had even gotten approval from the EPA to perform this experiment in the wild. 

Now all they had to do was convince the residents of Fresno that this was going to be a good idea. The pitch was basically this: 

“Hello there, neighbor! Say—a bunch of Silicon Valley engineers are going to be driving around in weird white cannon vans, shooting out millions more mosquitoes into your front yards. Ok, sound good?” What could possibly go wrong?

JODI: When you get out of the laboratory and you start to get into people’s neighborhoods and into their lives, you’ve got to have a stronnnng communication program. 

David: You mean, you think that ordinary citizens might not immediately love the idea of you guys air-dropping millions more mosquitoes

Jodi: I know. It’s just a—It boggles the mind that people just aren’t like, “oh, yeah, sure, whatever you want to do.”

Representatives from Jodi’s team and the Verily team held a series of community gatherings and movie nights, offering free Jamba Juice cards to anyone who’d show up.

Jodi: You had people that were either, “I don’t—I don’t care what you guys are doing. Especially if you’re going to do something about this mosquito because it’s driving me nuts.” 

And then you had the other side of— the other extreme, which is I mean, it just ended up being like a list of conspiracy theories, really. People that had all these thoughts as to what we were doing, that — that we were trying to do population control, that we were releasing insects that carried something that would make people sick and die. 

David: Wow.

Jodi: It’s—it’s disheartening. It’s hard to hear somebody say to you that they genuinely think you’re out to kill them. And so I try to —while I can’t validate that, I try to acknowledge it and say, I just—I just will not give up in trying to find common ground. It was it was a— it was a battle. 

And even once the Fresnonians were convinced that the project had value, she had to prepare them for—the vans. 

(Horror-movie chord sound)

JODI: Because it’s not an ice cream truck. They designed these vans that have these ginormous tubes that are really, really cool. And these tubes have literally thousands and thousands and thousands of mosquitoes, male mosquitoes inside of them. That is connected to basically an apparatus that sort of pulsates them out. It kind of blows these mosquitoes out of the side of the van.

In the summer of 2017, the Verily mosquito vans made their first runs, blasting millions of male mosquitoes into the sunny Fresno air. 

All they had to do now was wait to see the results.

Jacob: So we were actually able to see the results within about a week and a half or two weeks. Not— not to say that that was the end point, but we could see the impact of our releases. 

Jacob Crawford is a senior scientist at Verily—a mosquito biologist on the Debug team. To monitor the experiment’s results, his crew put out mosquito traps all over Fresno, and counted how many adult mosquitoes wound up in them. But he could also collect mosquito eggs around town.

Jacob: All we have to do is, is kind of cure them a little bit back in the lab, and then flood them as if it was raining, which is what they’re waiting for. And if they have mated with one of our males, then they’ll never hatch. 

Debug Fresno got a late start in the 2017 skeeter season; all that EPA paperwork had held them up. But when 2018 rolled around, they were ready. 

Linus: In 2018, we sort of had everything dialed in and everything ran really smoothly. Because it was our second time doing it and we got gotten a lot better at it. 

It didn’t take long for the team—and the town—to learn the results. 

David: And what were the numbers? 

Jacob: So the previous week we were seeing that something on the order of 70 to 80 percent of the eggs would hatch? And in the span of about a week or two, that —we took that down to zero. I did a dance at my desk. That was the strongest results I had seen and many, many moons. 

Jodi Holeman flipped through the binders of data that revealed how many female mosquitoes were showing up in the traps.

Jodi: Suddenly it’s like, zero zero zero zero zero, indicating no females and no females in the trap, no females in the trap. So that was very exciting. 

It was the biggest mosquito SIT experiment ever run in the U.S., and it was a grand slam.

Jacob: We managed to reduce the mosquito population by 95 percent… in the areas where we are treating compared to the areas where we weren’t treating. 

David: I would call that a success. 

Jacob: All that is a massive impact. Absolutely. 

David Do you think residents would notice? 

Jacob: Absolutely. Yeah. They went from not being able to use their backyards because the mosquito was so aggressive, to having a summer where they weren’t getting bitten. They were all saying the same thing: “Thank you. This has been a great, a much better summer for us.” 

Verily debugged Fresno one more time, in 2019—again, with spectacular results—but then that was it. From the beginning, Debug Fresno had been designed as a three-year test, a proof of concept for bigger and needier areas—like Singapore, an island nation with record-breaking waves of dengue fever. Last year, 35,000 Singaporians were diagnosed with this awful mosquito-borne disease, which brings extreme fever, internal bleeding, shock, and sometimes death—the highest number ever recorded in a year. 

Linus Upson’s team has partnered with Singapore’s government to develop a program called—Debug Singapore.

Linus: And so we’re in the process of building our first dedicated factory, to make mosquitoes in Singapore. It has the floor space to be capable of running a program for the entire country. 

Verily is also laying the groundwork for Debug Puerto Rico. 

Linus: The other place we’re working right now is, we’re partnering with the CDC in Puerto Rico. So we’ve been producing mosquitoes and shipping them to Puerto Rico throughout the entire pandemic. 

Pogue: Shipping them to Puerto Rico? From here?

Linus: Yes. It was easier to ship them from here than to build a factory in Puerto Rico.

Pogue: I see. How do you do that?

Linus: There was a lot of engineering work in figuring out how to safely transport mosquitoes in airplanes, at lower pressure, and sitting on tarmacs in the heat, and getting them out there. We have a special container they go in, and we control oxygen, and carbon dioxide, temperature, humidity, so they can all get there safely.

After Singapore and Puerto Rico, well, the world’s the limit.

Linus: We’re talking with a number of other places in the Caribbean and a number of other places around the world. We’re just now getting to the stage where we can take on multiple projects at the same time. 

Now, Verily is part of Alphabet, and Alphabet is a for-profit corporation; and ultimately, Linus Upson says that the Debug program has a business model.

David: So someday the governments will, in theory, pay the company to run these programs. 

Linus: That’s the plan.

If all goes well, Verily’s government customers will be able to save lives and save money.

Linus: So the way we’re approaching this from a business perspective, is we want to make the cost of this intervention substantially less than governments’ direct health care spend on dengue. 

David: OK, so if you can get rid of the mosquitoes in a certain region more cheaply than what a government is now spending to treat the disease, the government will say, well, then that’s worth it. 

Linus: Correct. 

I gotta say, I love this story. I love that a software engineer with a goal to save millions of lives might actually do it. I love that Verily’s approach doesn’t involve chemicals or genetic tampering. I love that this crazy program actually works. 

It all just sounds a little too perfect. Surely there’s some unwanted side effect. Surely these Silicon Valley geniuses have overlooked something.

David: What is there to be afraid of if this becomes a common technique? You know, are you depriving birds of their meals? 

Linus: So Aedes aegypti mosquitoes are invasive in most of the world. Humans spread them around the globe starting about 400 years ago. We’re the ones who are building all the habitat for them. We build gutters and storm drains and great places for mosquito larvae to breed. And so we have dramatically amplified their population all over the world. 

We’re the ones who, who created that population of mosquitoes to begin with. So from an environmental standpoint, we’re just cleaning up the mess we made in the process. 

David: It just it seems too good to be true. 

Linus: Unlike chemical pesticides, which, you know, are broad spectrum and kill a wide range of insects, one of the wonderful parts of the sterile insect technique is that is exquisitely species specific. You’re targeting just the one thing that you’re going after. And the sterile insect technique, we’ve been doing now for 70 years. It’s been one of the most successful interventions for crops and livestock. And now we just want to be able to also apply it to human health. 

David: So is there anything to worry about? 

Linus: We haven’t been able to come up with one. 

But if you live in Fresno, you might have one concern. What makes this sterile insect technique so safe and so controllable is that it affects only one generation of bugs. The males that you infect with Wolbachia don’t pass on Wolbachia, because, remember, they can’t make babies. So—no unintended consequences. 

Unfortunately, that SIT affects only one generation is also the bad news. Because if you don’t keep shooting Wolbachia males out of your vans, the wild mosquito population will bounce back. 

There was no Debug Fresno program in 2020, and there won’t be one in 2021. So for now, the era of Fresno’s beautiful, bite-free backyard barbecues is over.

Jodi: Basically yes, the population will rebound really quickly once you stop releases. Mosquitoes from outside neighborhoods, they’re going to move back in really, really quickly. 

Still, Jodi Holeman holds out hope that a Wolbachia project could return, or expand. Maybe Fresno, or maybe California, could become one of Verily’s paying customers.

Jodi: Can you imagine if you could roll out a program that started from, like, Southern California and just released slow and just— just gradually, knock this population out as it went up the state? 

Of course, it’s a massive effort. It’s an expensive effort, it has to be a coordinated effort. But I feel like, you know, there are some things that residents are willing to pay for. And when they’re being terrorized by mosquitoes, if you have something that you can tell them, “Hey, it’s 95 percent,” I think you’ll have strong support for funding a program like that. 

Now we’re going to send you out into the sunset with a special treat. Jodi Holeman’s
boss, Steve Mulligan, has a hobby. He writes song parodies about, if you can believe it, the sterile mosquito technique you’ve just been hearing about. With tremendous apologies to Nirvana and it’s song “Smells Like Teen Spirit”, take it away Steve!

(Steve sings parody mosquito song)