Does It Feel Like Mosquitoes Are Getting Worse?

Mosquitoes are the deadliest animal on the planet, and some of them may be on the rise. At least in listener Abigail Krich-Starr's area, that's due to warmer, wetter weather — which, yes, is linked to climate change. But it doesn't stop there: Ecologists and entomologists say increased heat could also alter mosquito behavior, shift their natural habitat, and even change how pathogens incubate and spread inside their bodies. So how do you protect yourself against the (mosquito) masses? Our experts suggested several things: - Assess your risk by checking local mosquito surveillance efforts, like this one for the state of Massachusetts https://www.mass.gov/info-details/massachusetts-arbovirus-update - Consider rescheduling outdoor events happening between dusk and dawn, which is peak biting time for multiple mosquito species - Wear long-sleeved shirts and pants, weather-permitting, to limit exposed skin - Use an EPA-approved DEET https://www.epa.gov/insect-repellents/deet#:~:text=DEET%20(chemical%20name%2C%20N%2C,such%20as%20mosquitoes%20and%20ticks.repellent, and/or a permethrin https://www.cdc.gov/mosquitoes/prevention/about-permethrin-treated-clothing-and-gear.htmlspray for clothing and outdoor gear This episode is part of Nature Quest, a monthly Short Wave segment that answers listener questions about the local environment. Got a question about changes in your local environment? Send a voice memo to [email protected] mailto:[email protected] with your name, where you live and your question. We might make it into our next Nature Quest episode! Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave http://plus.npr.org/shortwave. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

  This message comes from NPR sponsor, Viori, featuring the Sunday Performance Jogger. Receive 20% off your first purchase at viori.com/npr on any US orders over $75 and free returns. Exclusions apply. Visit the website for full terms and conditions.

• 0:19Speaker 01

  You're listening to Short Wave from NPR.

• 0:24Speaker 01

  Hi, everyone. Emily Kwong here, and this month's Nature Quest starts with one of our listeners, Abby Krishstar, who lives in Massachusetts.

• 0:31Speaker 02

  I grew up in the suburbs of Boston, and mosquitoes were terrible every summer. You know, I got tons of bites. I would swell up. It was so itchy. And then, in my 20s, I moved closer to the city, and I realized that there were no mosquitoes. I could leave my door open or windows without screens, and like, bugs didn't come in.

• 0:52Speaker 01

  And for this brief period of time, life was divinely, blissfully mosquito-free.

• 0:58Speaker 02

  And then, I don't know when it was, maybe about five years ago, I started to notice that suddenly there were mosquitoes again, just being in our backyard. Each year in recent years has become harder and harder. Like, last year, we couldn't even be out there.

• 1:13Speaker 01

  Now, she is locked in a battle with the mosquitoes of Cambridge. Her ping pong games with her husband outdoors are still getting cut short.

• 1:22Speaker 02

  Because we were just getting eaten alive.

• 1:24Speaker 01

  So Abby wants us to figure out, what is happening?

• 1:28Speaker 02

  Like, why is it that 15 years ago, in Cambridge, Somerville, there were no mosquitoes? And now, like, they're everywhere. What changed?

• 1:41Speaker 01

  I hate mosquitoes, but they are more than just a nuisance. They are a public health problem. So I brought on producer Hanachin to talk about it. Hey, Emily. Yeah, the CDC considers mosquitoes the most deadly animal in the world, in part because they're a vector for a whole host of diseases. There's malaria and dengue globally, West Nile virus and eastern equine encephalitis in the US. It's a lot. And what surprised me most, Emily, is that the same thing that's affecting mosquito populations in Cambridge and creating this spike that Abby noticed, it's also changing how diseases incubate and spread, which could really shift the landscape of scientific research.

• 2:24Speaker 01

  Today on the show, we get to the bottom of this Massachusetts mosquito mystery. We're covering why mosquitoes bite, how climate change impacts them, and what experts recommend we do to keep the bloodsuckers at bay. You are listening to Short Wave from NPR.

• 2:46Speaker 00

  Stay tuned for the following announcements and messages from our sponsors. This message comes from Mint Mobile. Ditch overpriced wireless and get premium wireless for less. Go to mintmobile.com/switch to see which plan works for you. This message comes from Bowlin Branch. Change the way you sleep with soft, 100% organic cotton bedding from Bowlin Branch, designed to help you fall asleep faster and never sleep hot while wrapped in luxurious comfort, airy blankets, cloud-like duvets, and breathable sheets. Experience pure comfort and feel your bedding get softer with every wash. Discover the difference with 15% off your first order at bowlinbranch.com with code NPR.

• 3:30Speaker 00

  Exclusions apply. See site for details. This message comes from Google Workspace with Gemini, one subscription that does it all. Personalized AI and premium business versions of Gmail, Google Docs, Drive, and more. Try it free for 14 days at go.gle/workspacewithGemini.

• 3:52Speaker 01

  All right, Shortwavers. We are on a nature quest, our monthly segment that brings you a question from a fellow Shortwaver who is paying attention to the environment around them and the ways it's changing. And this month, Hannah and I are investigating why our dear listener Abby is seeing more mosquitoes and what she and her neighbors can do about it. But let's talk about mosquitoes first, Hannah. Yeah, so I started by calling some local experts in eastern Massachusetts. And I asked them, have they noticed more mosquitoes?

• 4:22Speaker 03

  Oh, absolutely, yeah.

• 4:23Speaker 01

  So this is Doug Bidlak. He's an entomologist for the East Middlesex Mosquito Control Project. He's been working with them for the past 25 years.

• 4:30Speaker 03

  Our numbers have continued to go up since I've been here. Overall, and I'm talking about total mosquito population has been going up.

• 4:36Emily Kwong?

  So Abby, you are not imagining it. This is real. Did Doug tell you why, Hannah?

• 4:41Speaker 01

  Yeah, he says it's really tied to several different shifts in local weather, and all of them are linked to climate change.

• 4:48Emily Kwong?

  OK, so how is climate change affecting mosquitoes everywhere?

• 4:51Speaker 01

  So it's kind of hard to generalize because there are like 3,500 different species of mosquitoes.

• 4:56Emily Kwong?

  Oh, no, that's a nightmare.

• 4:57Speaker 01

  Yeah. In the Massachusetts area alone, there are over 50 different species of mosquito, and not all of them are thriving. For example, Doug told me that Aedes albopictus, commonly known as the Asian tiger mosquito, it's a non-native species they first started noticing in the area in 2017. Those mosquitoes do really well in hotter temperatures, and so they've been thriving. But other species are declining, maybe because they don't do so well in those conditions.

• 5:23Speaker 03

  It's been warmer. It's been getting wetter. But it's also become more volatile, more unpredictable. So we have one year where it's very wet and hot, and one year where it's very dry and hot. So some species are, there's winners and losers because of that.

• 5:40Emily Kwong?

  Overall, though, are there more mosquitoes in Massachusetts?

• 5:44Speaker 01

  Yes, that's what Doug said. And climate change isn't just affecting mosquitoes there. Last year, The Washington Post published a data analysis showing that in many parts of the US, mosquito season is multiple days or even weeks longer than it used to be. So again, like those hotter temperatures, increased rainfall, more volatile extremes.

• 6:04Emily Kwong?

  So the weather conditions that are good for mosquito life is getting longer in much of the United States. Does that mean that there are also more mosquitoes around the US, too?

• 6:16Speaker 01

  We don't know. That's because mosquito surveillance programs really vary across the country, so there aren't any exact numbers. But I talked to Rebecca de Jesus Crespo. She's an ecologist at Louisiana State University who specializes in mosquitoes. And she told me that these weather patterns are a pretty good indicator that overall, across species, mosquitoes could be thriving in these spots.

• 6:40Speaker 05

  Have an overall average trend of certain places getting closer to the ideal conditions where, on average, a mosquito would thrive. In locations where we already have a mosquito present, if those conditions expand temporally, you would have them there for a longer period of time.

• 6:59Emily Kwong?

  Yeah, I mean, that makes sense. More time to breed and make more of themselves.

• 7:04Speaker 01

  Exactly, and more time for them to spread diseases, which, by the way, is not the only thing that they do.

• 7:10Speaker 06

  So a lot of people think that mosquitoes are here on this planet just to bother us and bite us and annoy us, but that's not their goal.

• 7:19Speaker 01

  This is Julian Hillier. He's an entomologist at Vanderbilt University, and he says the goal of mosquitoes is the same as pretty much any other animal, right? They need to pass their genetic material on, which means that the female mosquito needs to lay eggs.

• 7:33Speaker 06

  To make eggs requires a lot of nutrients. So the goal of drinking blood, which, by the way, only females do, is to get the nutrients they need to make eggs so that they can pass on their genetic material to the next generation.

• 7:45Speaker 01

  But I will say, Emily, all those nutrients, they come with risks, like bloodborne pathogens.

• 7:52Speaker 06

  When you take that blood meal, a female takes that blood meal, she'll drink anything that's in the blood. So if a person is infected with something, she will drink that pathogen as well, so that when she takes another blood meal later on, that pathogen can be transmitted to another animal.

• 8:07Speaker 01

  And Julian says those pathogens are also affected by climate change because increased temperature changes how microbes might incubate in mosquitoes' bodies.

• 8:16Emily Kwong?

  Wait, tell me more about that.

• 8:17Speaker 01

  Okay, so humans are homeotherms, meaning no matter what the outside temperature is, our internal temperature remains constant.

• 8:26Speaker 06

  Now, mosquitoes don't do that. They're poeckilotherms, which means that they allow their temperature to fluctuate with the temperature of their environment. So in a mosquito, when it's warmer, the metabolism is much higher. Everything's going faster when it's hotter. And the idea is that they're also aging faster. For that reason, when you have warmer temperatures, mosquitoes generally have shorter lifespans.

• 8:52Speaker 01

  So Emily, when it's hot outside, it speeds up all of these processes in the mosquito life cycle. So biting, or laying eggs, or fighting disease, spreading infections.

• 9:02Emily Kwong?

  So they could be out here living fast, dying young, but be more deadly on their way out.

• 9:07Speaker 01

  Yes, and then there's a lot of other things to consider, like the individual species, or the particular pathogen, or the local environment. It's all very, very complicated. And not to throw one more wrench into it, but on a global scale, climate change is also causing mosquitoes' natural habitats to shift, which will also affect the pathogens that they spread.

• 9:29Speaker 06

  So the other thing that is going to be happening now is that you're going to have a geographical shift of what pathogens are where.

• 9:37Emily Kwong?

  OK, so it's impossible to say, really. It depends on where you are, how the local mosquitoes in your area are doing under your local specific conditions, and how it intersects with their lifestyle and their natural habitat. It's a very complicated question of like, why so many mosquitoes where I live?

• 9:54Speaker 01

  Exactly, and it's a complicated question that is changing a lot, which is why doing science and continued observation and surveillance of these mosquitoes is really important. And both Juliana and Rebecca told me there are so many things that affect mosquitoes and their ability to transmit disease beyond just the climate, the weather. There's the presence of humans or animals, and the urban heat island effect, and whether the mosquitoes are drinking enough water.

• 10:18Emily Kwong?

  Like whether they're hydrated or not?

• 10:20Speaker 01

  Yeah, Rebecca told me that matters, too.

• 10:23Speaker 05

  If you are in a condition where it's becoming less humid and the mosquito feels dehydrated and there are not many water sources, it might bite humans more often kind of to quench their thirst.

• 10:36Emily Kwong?

  So they're drinking our blood also just because they're thirsty and there isn't enough water for them?

• 10:41Speaker 01

  Yeah, basically, like, if they're thirsty, they're going to be more aggressive biters. And you're more likely to attract those mosquitoes when it's hot out, too.

• 10:50Speaker 05

  Like if your body is emitting heat, CO2, it's sweating, it's emitting all those.

• 10:58Speaker 05

  Metabolize. Mosquitoes use chemical cues and cues regarding to the body heat to find a human to bite. Like if you're outside and it's hot, it leads mosquitoes to find you.

• 11:10Emily Kwong?

  What a stupendous summertime feedback loop we have found ourselves in. All right. So, thank you for this incredibly thorough answer as to why so many mosquitoes. What does that mean, though, about living among them? How do we prevent mosquitoes from biting listeners like Abby?

• 11:28Speaker 01

  So I did ask our local experts what they recommend. And Doug said one of the things he'd tell Abby to do is check her backyard.

• 11:36Speaker 03

  Especially for like an Asian tiger mosquito, or for the species that spread West Nile virus, which are Culix mosquitoes, the larvae live in containers. It could be your gutters, for example. It could be a birdbath. It could be toys in your yard, that kind of thing.

• 11:51Speaker 01

  Really, anything that collects even a little tiny bit of water, because mosquitoes tend to stay pretty localized after hatching.

• 11:58Speaker 03

  And a lot of those species don't fly very far. I mean, you might be getting your next door neighbors, but you can cut down a lot on your own just from your own little property.

• 12:07Speaker 01

  And the other thing that Abby and the rest of our listeners can do is keep an eye on local mosquito surveillance. Doug's team is regularly capturing and testing mosquitoes for the pathogens that cause West Nile virus and eastern equine encephalitis. And the Massachusetts Department of Health has an online dashboard that they update regularly. It shows risk levels for every area in the whole state. We'll link to it in the show notes. Vivian Tseng is the Director of Public Health in Sudbury, just west of where Abby lives. And she says risk levels like those can help residents decide when to go out or when to stay in.

• 12:40Speaker 07

  The hours from dusk to dawn are peak biting times for many mosquitoes. So as risk is increasing, consider rescheduling outdoor activities that occur during the evening or early morning.

• 12:54Emily Kwong?

  Yeah, tough, because Abby, like I said, she and her husband love to play

• 12:58Speaker 01

  Ping pong out on their patio at night? What should she do about that? So Vivian says that if folks are working or playing outside, or maybe planning a camping trip, basically, if they have to be outside, they can try to cover up with long sleeve and pants and get a good repellent.

• 13:12Speaker 07

  I'm a huge fan of EPA-registered DEET repellents. I think that those are the most effective. And you definitely should check the product label to be sure on if you're using it correctly.

• 13:24Emily Kwong?

  Important to say, though, not everyone loves DEET. You should check for the safety of the product, particularly for infants. And there are other alternatives, but DEET, I guess she's saying, is what's most effective.

• 13:35Speaker 01

  Yeah. Vivian also recommended permethrin spray, which you can spray on your clothes to repel insects. It'll last a certain number of washes. And she says it's good for things like camping.

• 13:45Emily Kwong?

  Awesome. Hannah Chin, thank you so much for tackling this question.

• 13:49Speaker 01

  Anytime, Emily. Thanks for having me.

• 13:53Emily Kwong?

  Short Wave-ers, we are going to have Nature Quest on every last Tuesday of the month. So if you are observing something in your local environment and you want us to investigate with all the science might that we bring, email us your question at [email protected].

• 14:10Emily Kwong?

  This episode was produced by Hannah Chin and Rachel Carlson. It was edited by Rebecca Ramirez and fact-checked by Tyler Jones. Jimmy Keely was the audio engineer. Special thanks also to Sam Poulsen for writing the Nature Quest theme music. Beth Donovan is our senior director and Colin Campbell is our senior vice president of podcasting strategy. I'm Emily Kwong.

• 14:29Speaker 01

  And I'm Hannah Chin.

• 14:30Emily Kwong?

  Bite that follow button like a mosquito for us. Thank you so much. Talk to you later.

• 14:34Speaker 01

  Bye.

• 14:42Speaker 00

  Stay tuned for the following announcements and messages from our sponsors.