See A Spotted Lanternfly? Squash It!
If you live in Pennsylvania or any of its surrounding environs, you’ve probably seen a really interesting looking bug in the past few years: the spotted lanternfly. Around this time of year, it’s in its nymph stage. But when fully grown, these lanternflies sound a little like the joke—they’re black and white and red all over. They’ve also got spots, as their name suggests.
The charming news about how interesting they look is offset by the bad news: They are an invasive species. And they frighten crop farmers because they have a taste for just about anything, and a fondness for grapes, which could have dramatic economic consequences.
Many states have a unified stance on what to do if you spy a spotted lanternfly—stomp them out. But is that an effective way to stop their spread? Joining Ira to chat about stomping techniques and lanternfly biology is Julie Urban, associate research professor in entomology at Penn State University, in State College, Pennsylvania.
Invest in quality science journalism by making a donation to Science Friday.
Julie Urban is an associate research professor in entomology at Penn State University in State College, Pennsylvania.
IRA FLATOW: This is Science Friday, I’m Ira Flatow. If you live in Pennsylvania, or any of its surrounding environs, you’ve probably seen a really interesting looking bug in the past few years. The spotted lantern fly. Around this time of the year it’s in its nymph stage, but when fully grown these lantern flies sound a little like the joke, they’re black and white and red all over. They’ve also got spots as their name suggests.
The good news about how interesting they look is offset, of course, by the bad news. They are an invasive species. Sci-fi producer Kathleen Davis is here with her up-close and personal experience with these bugs. Hi Kathleen.
KATHLEEN DAVIS: Hello Ira.
IRA FLATOW: So Kathleen, what’s been bugging you.
KATHLEEN DAVIS: Funny, yeah, it’s interesting. So I have lived in New Jersey for a little bit over a year, and last year I saw probably one or two fully grown spotted lantern flies in my neighborhood in late summer. And they’re really distinctive looking, they look like moths. Kind of like the size of a cicada, for those listeners who have experienced brood 10 this year.
IRA FLATOW: Wow. That’s pretty big, isn’t it?
KATHLEEN DAVIS: Yeah, yeah they’re really big actually. So this year though, the plants around my house have been covered in these little black spotted bugs. And they are super distinct looking. Dare I say, they’re a little bit cute. They are black and they’ve got these white polka dots all over them. They also jump really far if you touch them. So I thought these are really funky looking bugs and I looked them up and sure enough, they are spotted lantern fly nymphs.
IRA FLATOW: Well if they’re an invasive species, what can we do? Anything about them, if anything?
KATHLEEN DAVIS: Well I have been trying to figure that out. But I looked it up and the main advice for getting rid of them is to stomp on them.
IRA FLATOW: Wait a minute, that’s the official advice? The high tech answer is stomp on them?
KATHLEEN DAVIS: I’m not joking, the state of New Jersey’s official instructions for what to do if you see a spotted lantern fly is, quote, “join the battle, beat the bug, stomp it out.”
IRA FLATOW: Oh wow. Well I’m putting on my stomping boots, Kathleen. Hoping my next guest can give you some more advice. Thank you.
KATHLEEN DAVIS: Thank you, Ira.
IRA FLATOW: And my next guest is Dr. Julie Urban, an associate research professor in entomology at Penn State University, State College, Pennsylvania. Welcome to Science Friday.
DR. JULIE URBAN: Hi, great to be here.
IRA FLATOW: Dr. Urban, do you agree that the best way to deal with a spotted lantern fly, as New Jersey says, is to stomp it out?
DR. JULIE URBAN: Well, it’s better than the alternative, which is to spread it, right? Trying to direct the public in how to effectively manage it and not transport it and further contribute to its spread is kind of a hard issue that we’ve been really wrapping our brains around for quite a while. So, the short answer is yes. That’s not to say that we’re not spending a lot of money on control efforts, but yes.
IRA FLATOW: Yeah, let me rewind a bit so we can talk a bit about how the spotted lantern fly became an invasive species. Tell us about the origin story there.
DR. JULIE URBAN: Yes, so the origin story– actually spotted lantern fly was an invasive that first occurred in South Korea in 2004. And so there it was reported to damage grapes, apple, stone fruit, and was a nuisance pest to residents. So we were all primed in the US and looking for it anyway. And so it was first detected, and reported to Pennsylvania Department of Agriculture, September 22, 2014. So they knew immediately what this thing was, confirmed what it was, and reported it to USDA, and immediately action was taken.
And so, it was suspected from where it occurred and from how we know it got to South Korea. And what we know about the biology of other lantern species, is that essentially they’ll lay their eggs on anything. They don’t require a host plant that their offspring can feed upon to be a viable host for their eggs. And so we suspected they were transported in that egg mass state on a shipment of stone. So they were either laid on the stone itself that was shipped, or on the pallet, and that’s how they got here from their native range. Which would be somewhere from China, Vietnam, Japan or India.
IRA FLATOW: So we’re talking about tropical bugs, right? I mean, Pennsylvania is not really a tropical state, well now with the 90s we’re having for the summer, I guess you could argue that. I mean, how is it that they’re establishing themselves so well in the Northeast.
DR. JULIE URBAN: And here’s where we get into some complexity of lantern flies. Lantern flies are a family of plant hoppers called fulgorid, there’s 500 species. And largely most of them are tropical, that’s what I study. But there are a few that occur in more temperate habitats and spotted lantern fly, Lycorma delicatula, is one of those. Its native range– you find it in Beijing, which is 40 degrees north latitude, which is the same as the north latitude of Philadelphia, New York City. So this is one of the very few lantern fly species that could get here.
And it is able to survive these harsher temperatures, winter temperatures, because it over winters in its egg stage. Not all lantern flies do that, other species do other things. So this is just one of the few outliers of this particular family.
IRA FLATOW: And that’s what makes them so good at spreading, is that they can survive.
DR. JULIE URBAN: Yes, that’s one of the things, that’s not the only thing.
IRA FLATOW: OK what else makes them so good at spreading?
DR. JULIE URBAN: They’re so good at spreading because they’ll feed so broadly on such a huge range of host plants. They’re sap feeders, so more specifically, their phloem feeders. And they’ll feed on essentially anything except for conifers. So they feed so broadly, so there’s plenty of different host plants they can feed on. Their biology doesn’t have to be honed in just the timing of any one plant. Because they’re feeding on so many different things they’re broadly diffused across the habitat so it’s really hard to know when they’re there, right, because they’re kind of spread out.
And then the other thing about them is that while they like a lot of things, they really like one host plant in particular that also comes from their native range, Ailanthus altissima, or tree of heaven. That’s an introduced invasive that’s here in the United States. It persists throughout the United States and it’s generally found in highly disturbed habitats, so along railroad corridors and roadsides. Once you know what tree of heaven looks like or smells like, you’re going to see it on the New Jersey turnpike, you’re going to see it everywhere.
IRA FLATOW: Is that the one with the long thin leaves?
DR. JULIE URBAN: Exactly.
IRA FLATOW: I call them junk trees, they’re everywhere.
DR. JULIE URBAN: It’s the kids book, a tree grows in Brooklyn, where the tree grows out of a crack in the sidewalk, right. And so basically because lantern flies are always moving around and their eggs are laid on anything, that lets them move along with Ailanthus along these corridors. And so that’s also how they’re able to spread.
IRA FLATOW: And what makes them so bad? I mean, if there are so many of these trees around, what are they attacking that we don’t like?
DR. JULIE URBAN: There’s two answers to your question. The first, what are they doing, what are they attacking that we like? They’re attacking grapes, right. They’ll feed on different plants throughout their lifecycle, but they’ll feed on grapes throughout their whole life cycle. And they’ll actually damage grapes. And so we’ve seen significant economic impact in actual vineyards.
The only other tree that they’ll actually kill is tree of heaven, otherwise they’re just a stressor to other trees. They’re not going to do a tree in and of itself. But the other way they’re so damaging in terms of their direct impact is that they can move around, right. And so they can get into goods that have to be shipped and we have quarantines for protection to prevent lantern fly from spreading.
So the other place we’re seeing economic impact is in the nursery industry, because you can’t ship nursery stock. These bugs will get into them even if they’re not feeding on those plants, like topiaries or conifers, they’re not going to feed on them, but they’ll certainly get into them. And they’ll get into Christmas trees and lay their eggs on them. And so now we have these nurseries and Christmas tree growers who have to spend a lot of money to keep them out of their products before they transport them. But also, anything else. If you think about them getting here on stone, they can get on anything. So this is a significant impact to any kind of company that transports anything over state or international lines.
But the other reasons why the lantern fly is so bad is because they evade our regular bag of tricks we have to control insects. So one of the things we often use to monitor insects is, figure out what is their chemical cue, what is their pheromone that they use in mating? Because then if we can use that we can build a lure and build a trap and we can use that for detection and trapping. Well, nobody’s found a pheromone for spider lantern fly, no plant hopper’s known to use a pheromone, so I’m not too surprised.
So we don’t have a really good war, or a way to trap them, and they’re really voracious so it’s really hard to rear them in a lab. I mean, we have a colleague at USDA, in particular, Tracy Leskey, who’s doing a great job developing a colony. But basically they live through one generation a year, you can’t grow them in the lab. And it’s really hard to grow them and say, hey grape vineyard grower let me put these on your grapes and kill them to understand their biology better. It’s really hard to study them.
IRA FLATOW: But there are people who are going to say, just spray them with insecticide.
DR. JULIE URBAN: Oh yeah, we joke harsh language kills them. So that is an effective way to go about it. But if you think about it, how you time that is very challenging depending on what they’re feeding upon. We don’t want to go in and spray pesticides on everything out there, right. We don’t want to hurt pollinators, we don’t want to hurt beneficial insects, we don’t want to just spread toxic chemicals everywhere. And so that’s one of the challenges that we’re trying to deal with.
And then where you get a particular problem for grape growers is that lantern flies will persist in their vineyard throughout the year. And we actually don’t even recommend additional insecticide sprays for the nymphs because what they apply for Japanese beetle will do them in, that’s fine. But later in the season is when grapes are close to harvest, and so we call that the pre-harvest interval. And so, any kind of insecticide you apply at that point can’t be very long acting, because you don’t want that to impact the grapes when they’re harvested.
And so what you’ll see in these vineyards is that at that time of year, first couple of weeks of September, lantern flies do this, to me, fascinating thing, they move. And you see massive lights. If you’re in New York City, you haven’t seen that yet, I bet you’re going to see it in the next couple of years. And so you’ll get thousands or tens of thousands on one particular tree. And so for vineyards, you’ll go into a vineyard, and they’ll spray a contact insecticide that’ll knock them down and kill a bunch. And you’ll walk through a vineyard and you’ll see just piles of hundreds or thousands of dead lantern fly underneath every vine. It looks like they’ve mulched with lantern fly.
IRA FLATOW: No kidding.
DR. JULIE URBAN: And more and more will keep coming in, and they just can’t keep up.
IRA FLATOW: And they’re spreading? Are they– I mean we’re talking about the Northeast, but I’m imagining that they’re spreading throughout the country then.
DR. JULIE URBAN: Well yeah, that’s what we’re worried about. I mean we’ve been working with California since 2018, they came out to look at this. Basically they’ve shown up dead on shipments to five other states that are not contiguous to Pennsylvania, including multiple times in California and Oregon. So we’re really, really worried about the grape growing regions. And because their food preference is relative to what’s around, right, they’re going to have changing impacts as they spread.
IRA FLATOW: This is Science Friday from WNYC Studios. Talking with Julie Urban research, associate professor in entomology at Penn State University in State College, Pennsylvania. Talking about the plague– it’s like it’s like one of the plagues of lantern flies. I understand that we know from our friends at a Public Radio station WESA in Pittsburgh, they told us about a story about a dog that’s been trained to sniff out lantern to fly eggs.
DR. JULIE URBAN: Yes, I think that’s really cool. So that’s something that Pennsylvania Department of Agriculture has, but also it’s a program that USDA is working on. And so the idea here is that– you’re not going to have them running through the forest, right really looking at trees, but in terms of pulling over cargo trucks that are shipping things. How do you inspect a truck and make sure that there aren’t lantern fly eggs on it? And so that’s a really good use of sniffer dogs. In terms of trying to find egg masses on shipments and prevent spread that way.
So with this insect, because it’s almost– it goes through four different nymphal stages, an adult stage plus the [? egg ?] stage. It’s kind of like you have to think about those six different stages as it being a different animal in each stage. And so in terms of trying to prevent the animal that is the egg from moving on cargo, sniffer dogs seem to be a very promising route. We don’t have any silver bullet, we just need a lot of tools targeted across each of those different stages.
IRA FLATOW: OK, leave us with your best advice for squishing them successfully.
DR. JULIE URBAN: For squishing them successfully.
IRA FLATOW: Yes, that’s what we’re told to do. Is there a technique, a method, a time in their life cycle, whatever, that’s the best time, way to squish them.
DR. JULIE URBAN: OK, for me, I like them. I would kill them, but not squish them. Frankly, rather than squish them, if you poke them in the rear end, or you put a bottle over their head, or some kind of container over their head. You can get them to pop up into a container, like into an iced tea container, into a soda bottle, whatever, and throw them in the freezer. That’s how I would do it. I wouldn’t want to squish, you can get a lot that way.
IRA FLATOW: Well, but now that you’ve got them in your freezer.
DR. JULIE URBAN: That’ll kill them, that’ll kill them.
IRA FLATOW: Oh I see, I see.
DR. JULIE URBAN: Yeah. That way you don’t have to be all violent.
IRA FLATOW: OK, good words, cause yeah, I’m all for that kind of technique. How would you rate the attack of this bug with other historic bugs that have attacked us before?
DR. JULIE URBAN: It’s different because, if you think about the emerald ash borer, you think about something that’s targeting trees, which this thing kind of is. Emerald ash borer, or something like that, is taking out species diversity. This isn’t, right. This is kind of a cross– gypsy moth will defoliate and it’ll like, just knock down and kill a lot of things. Other than tree of heaven and grape, nobody cares about tree of heaven. It’s not really killing things, it’s just more of a stressor in terms of its impact on the plants.
And it’s weird, because besides the great economic impact, this economic impact when it comes to transport of goods is where it can just hit so many different industries. Like I was sitting in a meeting at Pennsylvania Department of Agriculture and somebody– in one of the early years. And they have an inspector that will inspect like a certain percentage, 10%, of the beehives that get shipped out of state, because people raise beehives for pollination services that they’ll sell to California. And they’ll inspect those for varroa mites, and that kind of thing.
And they realize that like, oh my gosh, a lantern fly could lay its eggs on the underside of one of these beehives and get transported to an almond farm in California. And essentially now you just have a Trojan horse that you introduced there. And so now they have to inspect 100% of their beehives that leave the state. Like, holy cow. It’s like things you don’t think of. Milk trucks getting infested with egg masses on them.
IRA FLATOW: And of course, if we’re talking about going to California with all the grapes that are out there.
DR. JULIE URBAN: Exactly.
IRA FLATOW: I mean, could we expect shortages or increases in the price of wine if this really gets moving?
DR. JULIE URBAN: I think so. I mean, I talk with people from California, I have funding from California right now. I mean, they’re very proactive, but they’re very worried.
IRA FLATOW: We’re just about out of time. I have one more question for you, what spotted lantern flight info do you want to leave people with before we go? What’s the take-home message here?
DR. JULIE URBAN: I mean, maybe this is too nerdy, but for me who’s an evolutionary biologist, who studies fundamental biology suddenly like leading the national efforts on this, it shows the importance of studying the fundamental biology of species in their native range while their native range exists. Because you just don’t know when anything is going to be a problem. And you just better hope that somebody who is an expert is in the wings, who can help solve the problem.
IRA FLATOW: Julie Urban, research associate professor in entomology at Penn State University in State College, Pennsylvania Thank you Dr. Urban for taking time to be with us today and all this great advice.
DR. JULIE URBAN: Thank you so much. This is this was a treat.
Kathleen Davis is a producer at Science Friday, which means she spends the week brainstorming, researching, and writing, typically in that order. She’s a big fan of stories related to strange animal facts and dystopian technology.
Ira Flatow is the host and executive producer of Science Friday. His green thumb has revived many an office plant at death’s door.