Unwelcome Guests: What You Need to Know About Japanese Beetles in Washington State

In this episode of The Evergreen Thumb, host Erin Hoover sits down with Washington State Department of Agriculture Outreach and Education Specialist Cassie Cichorz to chat about what exactly Japanese Beetles are and what gardeners can do to protect their plants and slow the spread of these invasive pests.

Cassie covers why Japanese Beetles are a problem in our area, what plants are susceptible to damage by Japanese Beetles, what areas specifically have been affected by Japanese Beetles, and what to do if you spot one. 

She explains what they look like and gives information about traps that are used to catch Japanese Beetles. She tells listeners what the Washington State Department of Agriculture is doing to control Japanese Beetles and explains the history of how Japanese Beetles spread from the East Coast of America to our region.

Cassie also touches on other invasive pests in our area such as Northern Giant Hornet and Spotted Laternfly, and gives an update on how we are doing with controlling their populations.

• Japanese beetle in Washington State
• Japanese Beetle WSU Homeowner Control
• Common Insects and Mites: Spotted wing Drosophila (SWD)

[00:00:00] Erin Hoover: Welcome to The Evergreen Thumb. My guest today is Cassie Cichorz and Cassie is an outreach and education specialist with the Washington State Department of Agriculture. She is here today to talk to us about unwelcome guests in the garden. Specifically, we’re going to talk mostly about Japanese Beetles, but also, we’ll touch on the Northern Giant Hornet, what to look for, and what to do if these show up in your garden.

Thanks for joining me today, Cassie. Welcome to the show.

Guest Introduction

[00:05:13] Cassie Cichorz: Yeah, thanks for having me. I’m excited to share some knowledge and teach people about some invasive pests.

[00:05:23] Erin Hoover: Okay, why don’t you start by telling us a little bit about yourself and your work with the Washington State Department of Agriculture?

[00:05:30] Cassie Cichorz: Yeah, so my name is Cassie Cichorz. I work for the Washington State Department of Agriculture. I am an outreach specialist. So it’s basically my job to get information out to the people, let them know what’s going on, what’s important, and basically how you can help protect like your backyard, the whole state of Washington, and our natural resources, agricultural systems.

Japanese Beetles and Why They Are a Problem

[00:05:54] Erin Hoover: Okay. So one of the key things we wanted to talk about today was Japanese Beetles. So can you tell us a little bit about them and why there’s concern about their presence in Washington?

[00:06:05] Cassie Cichorz: Yeah. So basically, the first thing you have to think about is Japanese Beetle; it’s not from here. Um, it’s an invasive species.

So when it comes over here, there’s a couple of different impacts it has to us and we need to keep those in mind. Okay. The problem with Japanese Beetles is it comes in a couple of different stages. You’ll see it as adults in the summer and then it also lives as a grub or a larva in the soil. The problem with the adults is that they really don’t discriminate.

They feed on over 300 different types of plants. So, this will be buds of flowers, anything that’s green and leafy. What they do is they skeletonize the leaves and cause damage. Some plants, you know, aren’t as susceptible to some feeding and will grow back, but after repeated defoliation and repeated response, they will die.

Then when you flip it over to the other side and you have grubs or larvae, they actually live in the soil in pretty much our grassy areas. They like ornamental vegetation, so think, your turf. That’s gonna be your front yard, your back yard. Your, um, church, playground, school, and those big recreational grass areas are going to/could be impacted by the grub larva.

What they do is they move around in the soil and they eat the grass roots. So, there’ll be yellow patches or in really intense cases, they can eat all those roots off. It can lift up like a dead carpet. It’ll cause destruction to that system even more as well.

Plants Susceptible to Japanese Beetle Damage

[00:07:39] Erin Hoover: So aside from grasses, what are some of the more susceptible plants?

[00:07:44] Cassie Cichorz: Yeah, so when they’ve switched into the adults, right, they feed on over 300 different types of plants. So there isn’t much out of their wheelhouse. Essentially if it’s green and leafy or if it’s a flower. They love roses. So I know that’s kind of a bummer for a bunch of gardeners. If you have flowers around your house, kind of that ornamental, vegetational type they’ll get into it.

Some of our agricultural things, um, hops would be susceptible, grapes. Your trees and your bushes and things that are growing in your garden, the adults can feast on their leaves too. Buds of flowers, uh, fruit trees are also potentially there.

[00:08:21] Erin Hoover: So this could have large impacts on a lot of our primary agricultural crops in Washington.

[00:08:28] Cassie Cichorz: Yeah. It really doesn’t kind of discriminate.

Areas Affected by Japanese Beetles

[00:08:32] Erin Hoover: So what areas are currently affected by Japanese Beetles?

[00:08:36] Cassie Cichorz: So we are finding Japanese Beetles right now in lower Yakima Valley. If you get in your car in Yakima and you drive to the Tri-Cities, you might run into Japanese Beetles. So in 2020, we picked up three beetles, two in Sunnyside and two in Grandview.

The following year in 2021, we went ahead and trapped the area at a massive rate, putting out hundreds of traps to see how many beetles there are and where, and they’re pretty much in the Grandview area. The following year, you know, we did catch beetles again in the Grandview area, but they were starting to spread a little bit into Sunnyside.

We found some in Wapato and then coming into this year, it’s kind of the same thing, Wapato, Sunnyside, Grandview, also down into Mabton. I’m new this year, or I should say last year, you know when we were trapping, we found some in Pasco. So it’s kind of like that lower Valley. Um, but…

[00:09:34] Erin Hoover: They’ve already spread that much just in a few years.

[00:09:37] Cassie Cichorz: Yeah. So in the first year that we did the massive trapping, we caught a little over 24,000 beetles, in that Grandview, Sunnyside kind of Mabton area. Since then that has decreased to about 18, 500 beetles. So it’s calmed down. We’re catching fewer beetles, but there are those outliers for now. We’re seeing them in Wapato and unfortunately in Pasco and a couple more in Prosser, as well, or getting more towards those towns.

What Japanese Beetles Look Like and How to Identify Them

[00:10:08] Erin Hoover: So can you tell us a little bit about what Japanese Beetles look like and how we can identify them? Especially if you’re in that area.

[00:10:17] Cassie Cichorz: The best way to identify and describe Japanese Beetle is people will say, well, that kind of looks like a ladybug, but it’s actually quite different.

So about the size of your pinky nail, but the same general shape that a Ladybug would have, right? Um, but it is green and metallic-y, with copper wing covers. If you look at it, like, super close, it has little tuffets of hair on the side and the tip of its abdomen, but that green metallic color with the copper wing covers is going to be a pretty good, um, telltale sign when it’s the adult form.

You want to think to look for adults in the summer, basically anywhere from like mid-May to mid-October. We’ve started to see them kind of more towards June.

[00:11:01] Erin Hoover: Okay, and what about the grubs? What do they look like? Are they a specific color?

[00:11:06] Cassie Cichorz: The thing about grubs or larvae is they kind of all look the same when they’re coming out.

If it’s like a tan C-shaped grub, like we would describe the Japanese Beetle larva, it does have like a brown tan head and visible legs. It’s about an eighth of an inch to an inch long, um, and we’ll find it in the soil, but we kind of have to get it underneath the microscope to tell if it exactly is Japanese Beetle, especially if it’s in an area where, you know, it hasn’t been picked up before, um, because a lot of the beetles that pop out their grubs kind of look the same.

How to Prevent the Spread of Japanese Beetles

[00:11:40] Erin Hoover: OK. So how can we help prevent the spread of Japanese Beetles from becoming established in our gardens?

[00:11:51] Cassie Cichorz: Yeah. The best thing anybody can do is always be on the lookout for Japanese Beetle. If you see it, take a picture, and send that picture to WSDA. Right now, there are a couple more things too, that you can do.

Since we know that Japanese Beetle, you know, is over in Eastern Washington and a couple of those places, we know that it’s not in some other places. What WSDA does is we set traps across the state each year to help monitor for them. So you adding your extra set of eyes is another great way to be on the lookout for them.

Depending on where you live, you know, if you’re in an area near Japanese Beetle, you might want to get a trap and set it yourself. That’ll kind of be your first detector if you have Japanese Beetle. Traps come in different shapes and sizes. You can find them online at home and garden stores. But they’ll be the first detection to let you know if you have it.

They just kind of smell like roses or other beetles because they have a lure at the top. And then it’s basically usually a bag or a bucket. The beetle just gets caught in it and dies. We use that method across the state, you know, to see if it’s here, or if it’s not here. Then in those areas where we have caught the beetles, the traps catch the adults so they’re not able to lay as many eggs in the soil.

So it also helps kind of keep their numbers down.

What to Do if You Spot a Japanese Beetle

[00:13:15] Erin Hoover: So if someone does find Japanese Beetles in their garden, is there a way to interrupt their life cycle? Are there other control measures that they can use to try to protect their garden? Is there a way to interrupt their life cycle or otherwise control the Japanese Beetle if we do find them?

[00:13:36] Cassie Cichorz: So if you report Japanese Beetle and it’s confirmed to be Japanese Beetle, um, there are some tools and resources there for you out of the extension office on what you can do.

We’ll also be a resource, you know, telling you, “Hey, set a trap” that’ll go ahead and pick it up. But, you know, you’re not going to get into treating or managing for something unless you for sure have it. We’d also want to be able to get in that area and see if it’s somewhere else nearby if it’s spreading and monitor kind of that extent.

A Lack of Natural Predators for Japanese Beetles

[00:14:05] Erin Hoover: So are there any known predators or parasitoids of Japanese Beetles?

[00:14:12] Cassie Cichorz: It’s invasive and it’s not from here. What happened was it was first established in Riverton, New Jersey, and since then it’s spread about halfway across the United States. We just unfortunately don’t have the amount of predators needed to take care of it.

One beetle can drop 40 to 60 eggs, and once they get in, you know, that grassy area, they kind of have that unlimited buffet to really just thrive and live. So it unfortunately does kind of just come up to us to be able to go ahead and eradicate and get rid of them. We don’t really have the natural predators or things here that can really wipe them out, unfortunately.

About WSDA

[00:14:59] Erin Hoover: Is there anything else we should know about Japanese Beetles?

[00:15:03] Cassie Cichorz: I think it’d be nice to know maybe just a little bit more about what WSDA does, or kind of maybe what’s going on with Japanese Beetle in the West Side and why it’s so important. Right. We all know that, um, Washington, we have a big agricultural system.

You might have a garden in your backyard too, but we have lots of jobs. We have lots of money and exports and things like that. What happens is, um, it’s living kind of on the East Coast, if you ever look at a map. Basically in the 70s, The feds kind of came up with rules and regulations to keep it from spreading.

So us Western states, we monitor for it and make sure we don’t have it, right? We’ve actually been trapping in Washington since the ’90s. Now that we have Japanese Beetle, or any of our neighboring states if they find it, the first thing that we want to do is eradicate it, or we want to quickly get rid of it.

We don’t want to let it live here for multiple years so that it’s established and we’ve lost the chance to beat it. What could happen is if we turn into a state that becomes infested with Japanese Beetle, or we have areas of our state that are, and we have lost the hope to eradicate them, that could go in there and affect kind of our exports, um, or affect people’s ability to move things around in the areas where they live, because our neighboring states won’t want us to give them Japanese Beetle.

So, you know, it’s being neighborly and protecting your backyard, but it’s also kind of doing the good for all these people that have jobs, and that kind of that goodwill of our state.

Other Invasive Insects to be Aware Of

[00:16:47] Erin Hoover: So are there any other insects that we should be aware of and keep an eye out for that are trying to establish in Washington?

[00:16:55] Cassie Cichorz: Yeah, so in Washington a couple of the ones that we always tell you to be on the lookout for is Japanese Beetle. We’re actually still asking people to keep their eyes and ears peeled, I guess just your eyes for Northern Giant Hornet. You might have heard it as the Asian Giant Hornet, or you’re probably familiar with Murder Hornet. We haven’t seen that much or heard that much lately because we haven’t found any hornets or nests in the last two years, but we’re still surveying for them and looking for them going into this summer.

The third one to really be on the lookout for is Spotted Lanternfly. This has not made its way to Washington yet. Um, but kind of like Japanese Beetles started on the East Coast. Spotted Lanternfly did as well, and it has spread itself all the way to Chicago in about 10 years, which is a lot faster than some of the other insects have spread.

They travel pretty well, and they have been intercepted dead in some of our neighboring states to the south, so we know that they have the chance to get here. So that’s another good one to be on the lookout for.

[00:18:03] Erin Hoover: And the Giant Hornets, that was, if I remember right, that was primarily Whatcom County?

[00:18:08] Cassie Cichorz: Yes.

So we found, um, and removed four nests all from the area of Blaine. We’ve had multiple sightings, all in that Northwest corner of Whatcom County. We did have one down in Bellingham, but everything’s kind of been up in that area. You just have to remember, you know, if the hornets got over here once, it could have the chance to happen again.

So it’s always good to have your eyes open.

Threats Posed by the Giant Hornet

[00:18:30] Erin Hoover: What potential threats does the Giant Hornet pose in Washington?

[00:18:34] Cassie Cichorz: The Giant Hornet poses a couple of different threats to Washington. Their main threat is that they are huge predators of Honeybees. Instead of just eating one or two or three insects, kind of nabbing a pollinator out of the air, smashing it up, and eating it, they do go through this phase of their life where they get super hungry and can wreck an entire bee box.

Those boxes that you see sitting in the field could house 45,000-65,000 happy, healthy bees. And I just need a couple of hornets to wipe all those adults out in a matter of 90 minutes. So that’s kind of the huge threat that they would pose to us here in Washington if we lose our honey bees. That’s going to affect a lot of things down the chain.

There’s also the human health factor because no one wants to get stung by them. They do tend to guard their nests. But other than that, they just want to fly around and eat bugs. So we kind of have to work a little bit to get some there.

[00:19:34] Erin Hoover: Can you describe the Giant Hornets? I mean, they’re large compared to other wasps or, or hornets, but what are their distinguishing factor or features?

[00:19:45] Cassie Cichorz: So when you look, um, for a Northern Giant Hornet, it’s the world’s largest hornet. So that’ll be the first thing that kind of strikes out to you. It’s between an inch and a half and two inches in length. The second thing you’re going to want to kind of look at is its head. It’s very large and prominent.

It’s like as big and as wide as its body. It’s typically like a bright orange, yellow color. It’d be like me having a pumpkin on my head. You know, our heads just aren’t like that. The other thing you kind of can look for is on its abdomen. It has like these black and orange, yellow stripe lines. They’re kind of horizontal and straight across.

So there’s not going to be like spots or teardrops. Then the second thing about their nest is that they usually nest in the ground or in tree cavities. So if you see like an open \-face nest hanging from a tree, it’s probably not going to be one of these hornets.

The best thing that you can do is always take a picture, and send it to us, and we can do our best work to figure out what it is.

How Can Gardeners Help Prevent the Spread of Invasive Insects

[00:20:46] Erin Hoover: What kind of things can home gardeners do to help prevent the spread of these invasive insects?

[00:20:53] Cassie Cichorz: Some of the things that you could do as a gardener, you know, to help prevent the spread of invasive insects is kind of just in general prevent the spread of invasive species.

You know, when you’re gardening and shopping, if you have the option to plant something that’ll give you the same effect as a native plant, maybe you go that route. One of the things that I can tell you about Spotted Lanternfly or some of our other invasive insects that come over is they like to live and thrive on species that are from their origin.

So we have a big campaign for people to help identify Tree of Heaven. Help us map it and remove it if possible because Spotted Lanternfly uses it as its host tree. Other than that, you know, the best thing that you can do is really just keep your eyes open. Half of the invasive species that get reported each year come from the general public.

You see something and you’re like, “I’m not sure about that”. So you take a picture and you submit it to us and then, you know, just kind of try to educate yourself and your neighbors. If you heard me share a little bit about Japanese Beetle today, tell a friend or two. That really gets us helping to spread the word.

[00:22:09] Erin Hoover: So one thing that just occurred to me that could be an issue too, is a consideration is to pay attention to where your plant material comes from. You know, if you’re buying, if you’re getting, if you’re obtaining plants from somewhere other than a nursery, I’m thinking, you know, you go on vacation and you bring home, you know, a start from somebody’s garden or something like that, you never know what could be hitchhiking.

[00:22:32] Cassie Cichorz: Yeah, that’s very true. That’s very important. That’s why we know we kind of say buy stuff from a licensed nursery because you have to think about Japanese Beetle. It got here from the East Coast. Um, well, potentially, right? So I told you that those larvae, they live in the soil.

Well, in the summer, what the adults are doing is they’re eating something above the surface. They’re mating, they drop a couple of eggs, they go back up and mate again, eat, drop a couple eggs, and they continue that cycle. So, if you have a potted plant on the outside of your house, on your front porch, and they’re eating, that could get some eggs in it.

You bring it inside or you move or something. Then you bring it back outside and it’s going to hatch out a Japanese Beetle and it’s going to be in a new area.

Final Thoughts About Japanese Beetles and Other Invasive Insects

[00:23:18] Erin Hoover: Okay. Is there anything else you’d like to add about Japanese Beetles or invasive insects in general?

[00:23:24] Cassie Cichorz: The most important takeaway, when you’re thinking about invasive insects, Japanese Beetle, Northern Giant Hornet, you know, is if you see something, take a picture and report it.

The other thing to really take away is that you do a lot of good, in keeping your eyes and ears peeled, especially with like Northern Giant Hornet. We have trapping programs where citizens really get involved and help us monitor in areas that we’re not.

I know you guys are out in your gardens every day and looking for these things. So it really is cool to see us kind of educating and working together, for the common good of not just to protect your backyard, but to protect the whole of Washington state. So for that, the State Department of Agriculture is pretty thankful.

Especially, you know, if you’re just listening in to this podcast, you’re helping us spread the word.

[00:24:12] Erin Hoover: All right. Well, thank you so much, Cassie, for being here and telling us about Japanese Beetles and hopefully, we can stop them in their tracks.

[00:24:20] Cassie Cichorz: Yeah. Thanks for having me. The website if you want to find any information is agr.wa.gov/beetles.

[00:24:32] Erin Hoover: Okay. And we will put a link to that in the show notes so that it’s easy for everybody to find.