Brian Lehrer: Brian Lehrer on WNYC and for the last 15 minutes of our show, Rats in Your Cars. Ew, what? Rats can be found in almost every environment on earth. They are among the most successful mammals in the world, and their thriving population here in New York City has been a frequent topic for Mayor Eric Adams, who does not disguise his hatred and revulsion for rats. Their will to survive, though, sometimes takes them from the streets into homes, workplaces, and yes, even your car. For our last few minutes today, we're going to dwell on that last one.

Some recent headlines tell the story. Maybe you've seen this from Anna Tims in The Guardian, Help! A rat ate my car and it's costing me thousands, and from Ginger Adams Otis in The Wall Street Journal, A New York Professor Wages Epic Battle Against Rats Attacking His Car.

I'm sure some of you have your own stories to tell about the shock and horror of opening up the hood of your car to find a rat or even a rat's nest. What makes your car so hospitable to the ubiquitous quitter? Well, joining me now, Jason Munshi-South, urban ecologist and professor of biology at Fordham. We'll also talk a little bit about a guest essay he wrote in August in the New York Times under the headline, I've Studied N.Y.C. Rodents for 12 Years. The Enemy Is Us. Professor Munshi-South, welcome to WNYC. Glad to have you with us.

Jason Munshi-South: Thank you. I'm happy to be here.

Brian Lehrer: Listeners, who has a story about this to share? With the low winter temperatures now and the recent long overdue snowfall, did anybody listening open up the hood of your car just within the last few days to find a rat's nest for the first time, or maybe more than the first time? 212-433-WNYC if you have a rats in your car story or a rats in your car question. 212-433-9692. Call or text. Professor, you want to start by sharing a bit about your specific scholarly interest in rats?

Jason Munshi-South: Sure. I'm generally interested in how wildlife manages to survive and sometimes even thrive in highly urbanized environments like New York City. Traditionally, my research group has studied wild animals like coyotes, salamanders, native rodents that live in city parks like in the forest, but I found over the years that what people really wanted to know about is what rats are doing in New York City.

Back in about 2012, I decided I should start studying rats as well, even though they're not what we typically think of as wildlife, more of a pest. It turns out they're actually quite a fascinating species that exquisitely adapted to live with humans in urban spaces like New York.

Brian Lehrer: I will report that eight people instantly called in when I offered that invitation. We'll get to a few of those phone calls in a minute. What is it about cars that makes them hospitable to rats?

Jason Munshi-South: Well, we have over two million cars registered in New York City now, and that's increased since COVID, of course. Then we have all these people that drive in as well. Most of these cars are stationary and parked, not driving around the vast majority of time.

Rats are very curious and they like to explore their environment. They're very capable of using a lot of different places for nesting and hanging out, sewers, subway tunnels. They can grow into soil. They'll just hop up underneath a car and climb into the engine block and hang out in there because it's a warm space sheltered from the wind. If the car's not being driven around, it's quite safe.

I've actually had this happen to me. I lived in Jackson Heights for over a decade, and parked my car in an alley behind some row houses. There was a rat infestation back there at one point, and I'd see the rats running out from underneath my car and then found they had just created a little nest right on top of the engine block with little bits of food and things left over. These are just nice safe places for them when we have all these cars just sitting around.

Brian Lehrer: I think Josh in Harlem has a theory about something under the hood that makes it even more hospitable. Josh, you're on WNYC. Hello.

Josh: Hi. Thank you, professor, for raising the issue. I've had, a couple of times had to bring a car in for a wiring system completely replaced because I was told by a mechanic a few years ago, American cars started replacing the insulation in their wiring with a soy-based insulation and that the rats just love it. They eat it up like candy. I have the chewed-up wiring to prove it. It costs thousands of dollars.

Brian Lehrer: Thank you. Professor, you've heard that one before?

Jason Munshi-South: I have heard that. It's absolutely true that rats love gnawing on things like wires. They'll also gnaw on rubber and plastic parts inside of cars. Part of this is just because they gnaw constantly. Actually, the name rodent is derived from a Latin verb meaning to gnaw. They have very sharp incisors and it's how they explore the world. They smell things and they gnaw them to figure out what's going on.

This story has been around for quite a while, that perhaps we changed the plastics that were being used in car wiring. That's why we started to see rats chewing on wires. Nobody's actually tested that in a controlled setting to see if it's true, but it wouldn't surprise me. There does seem to have been an increase in rat damage to cars.

Once they get in there and start chewing on wires, it'd be very hard to diagnose exactly where they've interfered with the electrical system. It can be quite expensive even just to figure it out what's happened.

Brian Lehrer: We have another caller. I'm not going to take another caller saying the same thing as the first caller, but just to acknowledge that at least one other person is calling in to also say it's because of soybean oil in the wiring, or at least in part. Howard in Manhattan, you're on WNYC. Hi, Howard.

Howard: Hi there, Brian. I just got my car back from the mechanic after several thousand dollars worth of parts and labor were put in to repair rodent damage.

Brian Lehrer: Several thousand dollars.

Howard: Several thousand dollars.

Brian Lehrer: What did they eat?

Howard: They chewed up--

Brian Lehrer: Did you get the specific?

Howard: So many wires. They shredded the air cleaner. It looked like a party, and just shredded so many wires. I'm getting a copy of the parts list tomorrow, but it's a couple of pages of wiring.

Brian Lehrer: Howard, I'm sorry that happened.

Howard: [unintelligible 00:06:53]

Brian Lehrer: Did they give you any tips for prevention?

Howard: No. I garaged my car. A musician who I play with suggested that peppermint oil-- He had had the same problem in his car. He said peppermint oil. He was told- he's tried that will keep rats away. Don't know if it works or not.

Brian Lehrer: Sorry that happened to you, but thank you for reporting it so people know. Professor, I know you're not in the business of rat abatement, but any idea how to make cars even a little bit less hospitable to rats?

Jason Munshi-South: Well, nobody's really figured this out. People have tried peppermint oil and a bunch of other substances that are supposed to deter rats, but with enough rats around, it only takes one to get in there and not care that much about the peppermint and will start chewing on things.

Really, when I had my own issue with rats in the car engine block, it was only after the rat infestation was dealt with which was due to garbage cans not being secured in the alley in the back. Once that was done and there was some poison applied, the rats disappeared and that was that.

In terms of actually keeping them out of a car, I think that's going to be quite difficult if you're parking on the street or any open area in New York and there are rats around. These chemicals just don't seem to stop them consistently.

Brian Lehrer: Here is Parrish in Astoria, who's a service manager at an auto shop, who might have some advice. Parrish, thank you for calling in. You're on WNYC.

Parrish: Hey Brian, how's it going?

Brian Lehrer: Good. What you got?

Parrish: Are you there?

Brian Lehrer: Yes, can you hear me?

Parrish: Yes, I can hear you. I've definitely seen my fair share of rodent damage too, obviously what's been spoken about. The two main things I can basically tell people is that obviously if you have a vehicle that you don't use a lot, that's obviously something that'll really encourage them to not only go into your car but keep coming back.

There are, actually, products. I know you spoke about peppermint oil, but they actually do make packets now that you can actually just purchase. If you could have those in your engine bay and a couple of strategic places, it'll keep them from-- Anything that is a deterrent to help.

The other thing I can tell you is that if you have had rats around your car or what have you, it seems like they always come back to places that obviously they know. If you open your hood and see rat droppings or food wrappers or things like that, obviously they've been there and it's like, oh, well, this is a safe space for us. If you have something like that, I really recommend that you go get your vehicle washed under the hood, get a pressure washed at a detail shop, or something of that nature. You have to do these things. Obviously, nothing is 100% but if you do these things, it will mitigate your problem.

Brian Lehrer: Really good tips. Thank you so much. Here is Bob in Park Slope, who says he is a journalist who covers cars. Bob, you're on WNYC. Hi.

Bob: Hi. There's a solution to this problem and it sounds like it came from a cartoon. Honda developed a tape. It's almost like a duct tape that's impregnated with cayenne pepper. You wrap it around the wiring in your car's engine and it makes it unappealing to rodents. When you buy the roll of tape from Honda, it has this little cartoon of a mouse making a yuck face. It's hilarious, but it works.

Brian Lehrer: Cayenne pepper. Bob, thank you very much. Professor, any reaction to either of those callers from the industry, one way or another, with tips or the idea of rats liking their familiar territory?

Jason Munshi-South: I think all those comments were right on point. Rats are creatures of routine. They occupy pretty small areas, and they will just keep coming back to a car that's just sitting there and it's a nice spot for them.

As for the various chemicals, I think they can work, but you're going to have to be very careful if you really want to stop them from chewing on wires about keeping sure that those are applied, and so forth.

Cayenne pepper, any sort of hot chili is probably one of the better ones because mammals like rats are very sensitive to that. Rats have not only good taste but also a very strong nose, so that would be very irritating to them. Again, you're going to have to really apply that over all the wiring and so forth, or they'll find some area where they can do damage.

Brian Lehrer: A listener texts this question, "Are rats put off by the smell of diesel fuel?" Any idea?

Jason Munshi-South: That, I don't know about. I'm sure there are a lot of chemicals and smells and fumes and things that are irritating to rats, but there's so many of them, and if they're competing for food, none of these things are going to consistently deter them, I think, if they really want to access something like a car.

Brian Lehrer: Listener text, "I had a mechanic tell me to use powdered detergent." Another one texts, "My daughter's car was invaded by rats in Brooklyn, and although they didn't chew any wires, it smelled so horrible and it needed to be professionally cleaned." The stories keep coming in.

I guess we should say that it isn't just rats that can take refuge in the inner machinery of parked cars. Many small animals do. Squirrels, raccoons. People have found cats. I don't know if they do as much damage. Do you?

Jason Munshi-South: I know squirrels can get in there and chew on things. In other parts of the country, rabbits have been reported as doing a lot of damage. I think your cats and raccoons, those will be more in cars that are really semi-abandoned and just sitting there for a long time, and they'll just be using it as shelter. They probably won't be chewing on the car as much maybe to gain access, but they're not as driven to gnaw like rats are. They will definitely make a mess in there and you don't want them inside.

Brian Lehrer: Let me sneak Zef in Brooklyn in here who I think had a face-to-face encounter with a rat in their car. Zef, we have 20 seconds for you.

Zef: Hi. At the gas station, we pulled up and my mother got out of the car, opened the glove box, and a rat just looked up and said, "Why are you disturbing my home?" Then my mother jumped out and the car started to roll, [chuckles] and the rat did too.

Brian Lehrer: There you go. There's "the kicker" in the segment. In our last 45 seconds, professor, shifting gears slightly, pun intended, you wrote a guest essay in The Times about how in order to decrease the rat population generally in the city, we need to change our own behavior. What's the headline?

Jason Munshi-South: Yes. The number one thing New Yorkers can do to reduce rats is just not give them so much food. Don't litter on the street. Don't throw trash on the subway tracks. Don't add more garbage to the top of an already overflowing garbage can on the street. Just try to reduce your food waste overall.

We have these good pilot programs like municipal food, composting. The City is trialing better wrap-resistant containers rather than just throwing bags of garbage out on the street. That's really the solution. It's the only thing that's going to work in the long term. We can poison rats and reduce their numbers a little bit locally, but it's not going to be a long-term solution. I think that's [crosstalk]

[MUSIC -- Soulive: Solid]

Brian Lehrer: Jason Munshi-South, urban ecologist and Professor of biology at Fordham. Happy motoring.

Jason Munshi-South: Thank you.

Brian Lehrer: Stay tuned for Alison.

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