In the Swarm's Shadow - Locust Science

Ask A Biologist Podcast, Vol 135
Podcast Interview with Rick Overson and Mira Word Ries
Rick Overson and Mira Word Ries

Dr. Biology: 0:02

This is Ask A Biologist a program about the living world and I'm Dr. Biology.

Dr. Biology: 0:06

The insect world is filled with many amazing animals. Some are strange-looking, at least to some of us, and there are others that are beautiful. Yes, we know, beauty is in the eye of the beholder. There are those that can fly and others that can walk on water or even upside down on a piece of glass. And then there are those insects that can hop and fly like your common grasshopper, or for some parts of the world, locusts. 

Under most circumstances, we may not pay attention to these animals, but when locusts swarm and in large numbers, they can turn the sky dark. It's almost like twilight. These swarms have a big appetite and can eat just about anything they find. Locust plagues have been causing problems for humans since well, the pharaohs led ancient Egypt. Today, they can be just as destructive to crops and, for that reason, a risk to food supply and safety. 

Today I have not one, but two experts who are studying locusts and who can help us understand the complex roles these insects have in our ecosystem. Rick Overson is a research scientist in the College of Global Futures and part of the Global Locust Initiative at Arizona State University. Mira Word Ries is also part of the Global Locust Initiative and is the project coordinator for this team of researchers. Rick and Mira are also the creators of a new online tool called HopperWiki. You can think of it as kind of a locust central. For this episode, I have Rick in the studio and Mira is joining us remotely from the field. Next up, we explore the world of hoppers, grasshoppers, and locusts. Welcome to Ask A Biologist, Rick.

Rick: 2:07

Fantastic to be here, Dr. Biology.

Dr. Biology: 2:09

And Mira, thank you so much for joining us remotely.

Mira: 2:12

Thank you, Dr. Biology. Happy to be here.

Dr. Biology: 2:15

All right before we explore the world of grasshoppers and locusts, maybe we begin with the fundamental question. They may look the same to some of us, but grasshoppers and locusts, I suspect, are a little bit different. Who would like to give us the basics of grasshopper and locust physiology?

Rick: 2:35

Yeah, so one of the fascinating things about locusts is it's basically just a very special type of grasshopper. So, there's thousands of grasshoppers. Depending on who you ask, there's about 19 species of locusts, and you would never know it from looking at them. So, they’re tough survivors. They persist in really hot, dry areas like the Sahara Desert or the Sahel region, which is hot and dry, a massive area. They sort of live there at low levels and then, when times of opportunity come, and times of plenty come, they are able to respond to their environment in this dramatic way. 

So, they can change color, they can change their brain chemistry, they move down a different path and they morph into this other form. They become attracted to one another and eventually they can start to march across the ground in massive formations and, if these good conditions persist, eventually they become adults and can take to the skies.

Rick: 3:39

And so, this ability to turn into this other morph is something that only grasshoppers few can do. It's an ability that's coded deep in their DNA, and so a lot of times when we think about traits that DNA codes for, we think of, maybe, someone's height or their eye color, but this is a very different type of thing that is called phenotypic plasticity, and scientists like to make up complicated terms for things. That phenotype is just your form, and plasticity is like plastic. So, if you think about something that's plastic or mobile, and so a researcher thinks that phenotypic plasticity is this ability to morph into this completely different form in response to the environment. 

Dr. Biology: 4:25

Right, malleable. They have the ability to change.

Rick: 4:36


Dr. Biology: 4:27 

So, there are these two different forms and I think I read that when they are individuals they’re in their solitary state. Then when the conditions are right they become more social and form these huge groups that can become swarms – and then we use gregarious to describe them. 

Rick: 4:48

Exactly, scientists’ kind of think of these two different forms as solitarius and gregarious. The solitarius form is something that we would think of as sort of grasshopper normal. What it normally normal does for a living is it hangs out in the field, it nibbles on plants, and this gregarious form is what we usually see or think of when we're thinking about these locusts.

Dr. Biology: 5:11

So, Mira, where do we find grasshoppers and where do we find locusts? Because I'm getting the idea that all locusts are grasshoppers, but not all grasshoppers are locusts. So where are we going to find them today? Because I'm assuming they've changed over the years.

Mira: 5:14

Yeah, that's exactly right. Here in the United States, we used have a locust called the Rocky Mountain locust, but that is extinct now. We have plenty of grasshoppers of here in the US. Many of them are pests in the rangeland western United States but they are not technically locusts, although you may see them sometimes covering highways and even fence posts and causing trouble on grazing lands and crops. 

But typically when we think about locusts, as Rick said, Africa has many different types of species of locusts. Primarily we think of the desert locust as being somewhat troublesome, and the Middle East, in India, Pakistan, the Caucasus, in Central Asia, and China. There can sometimes be a locust in Europe, the Italian locust. At the moment there's also a locust that causes trouble for agriculture in South America and in Central America.

Dr. Biology: 6:35

So, Rick Mira mentioned the Rocky Mountain Locusts. When were they active?

Rick: 6:41

Yeah, so the first stories and reports I think started up in the late 1800s and then by the early 1900s, short time after they darkened the skies, they mysteriously went extinct. Kind of a forgotten chapter of American history that was very dramatic at the time and halted westward expansion for a time. It was written about in Little House on the Prairie by Laura Ingalls Wilder, but now is largely forgotten.

Dr. Biology: 7:09 

Alright, so we'll get back to these locusts. We know they're around the world. They're not in North America so we don't have them there, but we have them in quite a bit of mainly dry areas.

Mira: 7:23

Some of them, but they also do well in some hot and humid climates, like in Mexico, the Central American Locust. So, we primarily think about them as being desert adapted species, but there are differences across and so we can't say always.

Dr. Biology: 7:41

I'm going to ask this question, you're going to say, well, if we knew that answer, we wouldn't have to do more work. [laughter] What causes locust swarm?

Rick: 7:49

Yeah, that is a big question and I think it's one of the fascinating things about working in this space of trying to understand these dynamics. So, for perspective, I think we, as you mentioned, know about these swarms going back to the time of the Old Testament and the Quran they were written about, but certainly these locusts were doing this for eons before that. They're a natural part of ecosystems and so they've been swarming and doing this thing since time immemorial.

Dr. Biology: 8:24

But we don't really know exactly what triggers it.

Rick: 8:27

The main thing, if you had to pick one thing, to say that triggers it, especially in the case of the two locust species that are most economically important and most damaging, is rainfall. And so, they are able to survive at low levels in these dry areas, as we've said, but they also can quickly respond to their environment and capitalize on these dramatic rainfall events that turn desert areas into lush oases overnight.

Dr. Biology: 8:55

So once a swarm starts, how do we stop it?

Mira: 8:59

That is the million or, I guess, billion-dollar question because often that is what it costs to control these types of outbreaks. So, if you think about locusts, they don't know the difference between countries and borders and people and places and languages. So, it turns into a pretty big effort to coordinate across different countries, oftentimes, like in the case of the desert locust, where the campaigns end up being a lot of manpower and a lot of organization and really trying to control these locusts with pesticides, unfortunately. 

So that means spraying them by plane and also with folks going out on the ground and actually looking for them in often really remote and hard to reach places. So, you can kind of see the challenge where these very highly mobile creatures are off to the races, eating everything in sight, and we're usually a few steps behind them trying to control them. So, it's a big effort indeed and often it triggers a pretty big emergency.

Dr. Biology: 10:08

All right. So, I guess the answer here is catch it early.

Mira: 10:13

That is exactly the answer. So, we talk about preventative management a lot, and that means working together with forecasters, who are paying attention to weather patterns and where rainfall is going to hit and where we think locust outbreaks are going to originate, and then doing everything we can to be prepared and launch these control campaigns early.

Dr. Biology: 10:37

We talked about these swarms. I talked about the skies going dark, but have you seen the skies go dark?

Rick: 10:43

I have never seen the swarms. What I have seen are the marching locusts, which are very impressive, hundreds of thousands of individuals marching across the landscape. But the scales of these swarms in the desert locust outbreak are very hard to exaggerate. So, you can imagine these are large grasshoppers, like the size of a man's index finger. But hundreds of millions of those locusts will look like dust or smoke on the horizon and they will fly by for maybe three hours at those densities. And that's one small subswarm in a larger outbreak area. So, you can have these areas of hundreds of square kilometers where small swarms the size of Manhattan are flying around in a larger outbreak that can last for years.

Dr. Biology: 11:36

Wow. Mira. What do locusts like to eat? Or maybe I should say what don't they like to eat?

Mira: 11:42

Well, when they're swarming, they will eat the clothes off clotheslines. So, they essentially will eat everything in their path. But if you want to get into more nuanced nutritional ecology, we could have an earful for you.

Dr. Biology: 11:56

OK, so do locusts have a favorite food besides clothes on the clothesline?

Mira: 12:01

That could arguably be the doughnut diet, and it may be because of their fueling up for their marathons of migration, which is something that we are investigating here in our lab at ASU and around the world.

Dr. Biology: 12:20

Now there might be some people listening to this podcast who have visions of locusts swarms converging on the local doughnut shops. But that is not why we call it the doughnut diet. So why do we use that name? 

Rick: 12:31

Yeah, so I think one of the things that's interesting is that locusts can be thought of as vegetarians, so they largely eat plants. So, if we think about like a human who's a vegetarian or a vegan, someone might be concerned that they get enough protein in their diet. And so that's what researchers thought about locusts for a long time they thought, well, they're eating grass, they must really be hungry for protein. But it turns out that continuing research by our team at ASU and other collaborators and colleagues have shown that in many cases, especially when they're in this adult form where they're needing to travel long distances, they actually prefer to eat a carbohydrate or sugary doughnut diet and they perform better when they eat these sort of more sugary foods.

Dr. Biology: 13:26

So what Miro was saying? It's kind of like the marathon runner they want to build up on those carbs so they can do those long marches or flights. Right, got it. So, they're wow, so many of them and they can eat the clothes off your clothesline. Hopefully, not the clothes off your back. What have farmers been doing about this on their own? Is there anything they can do on their own?

Rick: 13:56

Yeah, so when you see, for instance, when these outbreaks get to extreme levels that we've been talking about, there's not very much that can be done. You see sad images of individuals that are trying to shoo the locusts out of their fields or bang pots and pans, and then, as Mira mentioned, there's a lot of pesticides spraying for control campaigns. But when things get to a level of a huge swarm, it becomes very difficult, even with massive coordinated efforts, to sort of punch back this locust swarms. You're almost metaphorically fighting a massive fire.

Dr. Biology: 14:35 

Right. Again, it's really important to stop these things before they even happen.

Mira: 14:42

There is an idea where, if we're looking at the locust management from a preventative standpoint, then we can think about how farmers are managing the land and the soil specifically because in the soil we could have a reservoir of nitrogen with different soil management practices that help build that up and then therefore those plants might be higher in nitrogen and less appealing to those locusts. So, from a long-term sort of sustainability perspective, there are things that farmers can do to help manage local populations where those fields and crops that they're growing may be less appetizing. The more we think about working and using locust biology against them if you will.

Dr. Biology: 15:35

Miro talks about working with quite a few people. One of the things about science research is people have this vision of the lone scientist in the lab and it's no longer the lone scientist. There's quite a few people, that typically teams like your team, but beyond that, you also have to engage other participants if you really want to be successful, in particular, with locusts. Let's talk a little bit about the teams that you have to have in order to make this work.

Rick: 16:06

Yeah, I think this is one of the things that's really fascinating about the locust problem. At face value it seems deceptively simple, other than the fact, as Mira mentioned, that these bugs are really good at growing. They come out in huge numbers. They can move across many countries. So, there's these problems of scale, but the locust challenge is also even more deceptively complicated than that, in some ways down at the level of even locust brains and the behavior of an individual insect that is interacting with something that's almost meteorological or almost like a weather event in scale. 

And research over the last decade or so by our team and others has shown that, perhaps not surprisingly, there are connections between the way we behave as humans and locust outbreaks. And so, as I said before, these are natural processes, locust outbreaks, but humans through modifying the climate and through modifying the way we use the land for agriculture and ranching, we are modifying the frequency and the places where these outbreaks happen. So, one of the ways to work at solutions to more sustainably managing them involves working with all of the people that these areas overlap with, so farmers, politicians, people who make decisions about the land, researchers and many others.

Dr. Biology: 17:37

Right. It doesn't surprise me. It also gets us back to what I was talking about at the beginning of the show, and that's Hopper Wiki, what I'm calling locust central. [laughter] You and Mira created HopperWiki. Whose idea was it first?

Rick: 17:54

We might have different versions of that.

Mira: 17:56

Oh, it's Rick. Rick is the wiki wizard, as I call him.

Rick: 18:00

I think the idea of doing it arose pretty organically. During the last desert locust outbreak, which happened during COVID. As an insult to injury. It was a large locust outbreak in Africa and the Middle East that lasted for multiple years. At the Global Locust Initiative here at ASU, we received a huge amount of requests for emergency information and help. There was a lot of chaos in the panic of all the coordination that needed to happen. And so, we started to put files and resources and fact sheets and pesticide manuals and grasshopper identification guides in Dropbox folders and Google Drives and eventually realized the need for a place where all of these people that we've been talking about can access a central location of information.

Dr. Biology: 18:55

Right, so we're talking about Mira, you have been really working on Hopperwiki. Let's talk a little bit about your involvement.

Mira: 19:06

Yeah, my involvement has been working along with Rick since the idea came to be, and Rick is the mastermind, which I feel like he understands all the things under the hood. So the nuts and bolts of the technology, of how we write, code and script and how things work together, and I am not that, but I am definitely devoted to creating content, thinking about the design, being able to think about the user experience, and, of course, we're both thinking about these things, but this is something that I've really gone in deep, so doing some writing and trying to make the experience great for our users.

Dr. Biology: 19:52

Because it's a wiki, I'm assuming you're going to be asking the community to actually contribute to the entire project. How do they get started?

Mira: 20:06

That's a great question and we are so excited for this next phase. It's as easy as going to and clicking on the right. There's a button that says request an account, and that's a great way to just get in touch with us and then we can start the conversation from there. So, we're really looking for folks with expertise in any of these sorts of disciplines that touch on locust biology or social science or management or any different perspective from all these different stakeholders that we've been mentioning are an important piece of the puzzle. We want to hear from you.

Dr. Biology: 20:47 

Okay, you named a lot of the I would say the science community. What about farmers, ranchers, politicians, have them chime in?

Rick: 20:58

Yes, we would absolutely love that, and we actually have another website that has been a small success. That's about two years old now. That's called Hopperlink, that we jokingly call LinkedIn for locusts, and that is more of a private social network for many of these people who work in this area. We have representatives from the UN there, representatives of farmers groups, researchers, students, grasshopper enthusiasts all communicating there. So, we would very much like to engage that community and anyone of interest within the sound of my voice to help produce content on Hopperwiki.

Dr. Biology: 21:39

Let's hope this gets some people interested in participating. 

Before the two of you get to leave, there are three questions I always ask my scientists. I'm going to start with Mira. 

Mira, the first question is when did you know you wanted to be a scientist or involved in the world of science?

Mira: 22:02

I think I could pinpoint it to working on a tea farm in Ecuador and I was digging around in the soil, and we were taking samples to think about how the soil ecosystem is impacting the plants that they were growing. And I just thought that was so cool that I wanted to continue digging around in the soil. And when I got back I started applying for master's programs and I luckily got connected to Dr. Cease and her work with locusts and soil and ecology and I got hooked.

Dr. Biology: 22:46

All right, Rick, I know you're hooked. When did you get hooked?

Rick: 22:50 

When I was three years old, I had my first memories of fistfuls of worms and mayonnaise jars filled with beetles, to the chagrin of my mom escaping in the house. So,  I've always been obsessed with insects. And it was later on as an undergraduate I majored in biology and my parents didn't go to college, so I wasn't really sure how grad school worked, and luckily I met the right professors in my junior year and realized oh my gosh, this is the thing you can do for a living. You could study insects for a living, and the rest was history after that.

Dr. Biology: 23:27

Okay, so now I get to the second question. I'll stay with Rick, and this one is where I'm a little evil. [laughter] I take it all away. Yeah, you know If you've listened to the show. It's a thought question, so no one freaks out. I'm not actually taking your job away or career. [laughter]

But I'm going to say you can't be a scientist, you're not going to be a teacher, because everybody falls back into the world of teaching, which is wonderful. I love it. So, what would you be, or what would you do, if you weren't a scientist?

Rick: 23:56

Whoa, yeah, that's the hardest question I've ever been asked. If I couldn't be a researcher. I love the outdoors, so I would be very interested in working with groups of people to go backpacking or mountain climbing or do things in the outdoors.

Dr. Biology: 24:17

Right. Run those adventure excursions for people that like to go out in nature. 

Rick: 24:18


Dr. Biology: 24:19 

Yeah, [it would] be good. All right, Mira, you got a little bit of a reprieve. You got to think about this for a little bit. What would you be or do?

Mira: 24:32

I don't even think I would have had to think about it, honestly, but I love digging around in the dirt, so I think being able to be a full-time gardener and hobby farmer would be my calling. I'd probably adopt a herd of sheep and a few horses and chickens and goats and just have a full on menagerie. So that would be my dream. I know that farming is the hardest job in the world and a shout out to everyone who is doing that full-time and I would love to learn more about that and grow food and just be connected to the animals and the land.

Dr. Biology: 25:13

I like that and you're in good company. A lot of my guests have said that they'd like to be a gardener or a farmer. So, Mira, the last question. You ready? 

Mira: 25:28


Dr. Biology: 25:29

I want to know what advice you'd have for someone who wants to be you. And to be clear, you're a project coordinator. Let's talk a little bit about the job of a project coordinator and how someone could become you.

Mira: 25:47

A project coordinator gets to do a lot of different things, because what are we doing? We're coordinating projects, so that means that I'm not always in the lab or doing science directly, although sometimes I get roped into field seasons and get to collect data and catch locusts and all that good stuff. But ultimately I like to help put the spotlight on our research that the team is doing. So that means helping with projects like HopperWiki to get educational resources out to the public, to work on our website, to write content, to work with students. I just get to have my hands on a lot of different things. So, I really enjoy that part of the job.

Dr. Biology: 26:34

So, I would say you're a wrangler right? 

Mira: 26:44


Dr. Biology:  26:14

In your theme of farming and ranching type of thing. You're the wrangler. How does someone become a wrangler?

Mira: 26:45

I think, follow your curiosities. If this is something that speaks to you, then that's what I did, and I really am a proponent of that sort of philosophy of follow the breadcrumbs and eventually you'll be led to something that is a good fit for you and has a lot of potential to satisfy your different curiosities. If you're like me I've never been able to settle for one thing so doing something that has different outlets and ways to work with different people then just keep on one step in front of you.

Dr. Biology: 27:21

All right, Rick, you got your reprieve this time. What advice do you have for future scientists?

Rick: 27:30

Yeah. So, I would share some similar sentiments to Mira. This is possibly a non-answer, but I had no idea that I would have this job today when I started even college or even started grad school, and so everything that I'm involved in today came through hundreds of interactions of like taking risks and getting involved in projects and meeting people and constantly kind of figuring out, as Mira is saying, like what things do I find rewarding. I always knew that I loved insects and I wanted to work with insects, but it's not easy to just finish college with an entomology degree with insects and then just start with a company immediately. And so all of this is kind of following your passions, getting involved, volunteering when that's feasible, and networking and figuring that out.

Dr. Biology: 28:28

Yeah, in particular, the volunteering and the networking probably leads to more success in getting the career you want than just about anything else.

Rick: 28:36


Dr. Biology: 28:37

On that note for the two of you, thank you so much for being on. Ask A Biologist, Rick. Thanks for being here.

Rick: 28:42

Absolutely fantastic, thank you.

Dr. Biology: 28:45

Mira, thanks for beaming in.

Mira: 28:47 

Thanks so much for having me.

Dr. Biology: 28:48

You have been listening to Ask A Biologist, and my guests have been Rick Overson, a research scientist in the College of Global Futures and part of the Global Locust Initiative at Arizona State University. Also joining us remotely, we had Mira Word Ries, who is the project coordinator for the Global Locust Initiative, and the two of them have been creating what I call Locust Central, or what they call Hopper Wiki, and for those listening in, we will include a link to HopperWiki so you can pop over there and check it out for yourself. 

The Ask A Biologist podcast is produced on the campus of Arizona State University and is recorded in the Grassroots Studio housed in the School of Life Sciences, which is an academic unit of the College of Liberal Arts and Sciences. 

And remember, even though our program is not broadcast live, you can still send us your questions about biology using our companion website. The address is, or you can just use your favorite search tool and enter the words Ask A Biologist. As always, I'm Dr. Biology and I hope you're staying safe and healthy.

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Bibliographic details:

  • Article: In the Swarm's Shadow - Locust Science
  • Episode number: 135
  • Author(s): Dr. Biology
  • Publisher: Ask A Biologist
  • Date published: March 23, 2024
  • Date accessed: June 12, 2024
  • Link:

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Dr. Biology. (2024, March 23). In the Swarm's Shadow - Locust Science (135) [Audio podcast Episode.] In Ask A Biologist Podcast. Ask A Biologist.

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Dr. Biology. "In the Swarm's Shadow - Locust Science." Produced by Ask A Biologist. Ask A Biologist Podcast. March 23, 2024. Podcast, MP3 audio.

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"In the Swarm's Shadow - Locust Science." Ask A Biologist Podcast from Ask A Biologist, 23 March, 2024,

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