Eradicating the Asian Longhorned Beetle

Joel Houle

If you’ve been on a trip outside the country, when you come back, Border Service Agents will ask you a few questions. And one of those questions will be whether you’re bringing back any food, plants or animals. And there’s a good reason for that.

If you introduce a foreign species to a new environment, even by accident, it can wreak havoc on the ecosystem. On this episode, we talk to a scientist who has been dealing with one of these foreign species. What kind of insect is black and white, about the same length as your thumb, and likes to get around by hitching rides on your car? Well, we’re about to find out.

Joel Houle

Welcome to a new episode of Simply Science. Our podcast that talks about the amazing scientific work that our experts at Natural Resources Canada are doing. My name is Joel Houle. And joining me is my astute co-host, Barb Ustina. Barb, how are you?

Barb Ustina

I'm doing just great today. How are you doing?

Joel Houle

I'm good.

Barb Ustina

It's so nice to be back and recording podcasts. That's one of my favorite parts of this job for sure. But before we get too far ahead of ourselves, I just want to bring up some exciting new changes here at Simply Science. And if you've checked out our website lately, you might know what I'm talking about. We've updated our site, and we have brand new social media channels on Twitter, Facebook and Instagram — and as always, on YouTube. So if you haven't seen them, I urge you to check them out. They look amazing! The whole team has done such a good job with these channels, and I'm really happy to be part of them.

Joel Houle

Oh, they look absolutely amazing! You're right. So, Barb, today we're going to be talking about the Asian longhorned beetle. Are you familiar with this insect?

Barb Ustina

You know what, true confession here. I've never heard of it before. And I've never seen one of them before. So this is all new to me, and I'm really looking forward to it.

Joel Houle

That's good. Well, you're going to be learning. I feel like I'm coming into this episode with a little bit of an advantage. My kids are a big fan of the Kratts Brothers, the Wild Kratts TV show. It's on Netflix and basically, the Kratts brothers, what they do is they teach kids about all sorts of animals. And I recently saw an episode on the Asian longhorned beetle. So I do see myself now as an expert having watched those 22 minutes.

Barb Ustina

Yeah. I don't know what our guest would have to say about that, but, you know, I'll let you get away with that one.

Joel Houle

Well, 22 minutes, 30 years of experience, it's kind of close. So you know what? Why don't we bring in our expert? That way, we can end the episode, both of us being experts on the insect. What do you say?

Barb Ustina

Sounds great. I'm really looking forward to this!

Joel Houle

Okay, let's do it.

Joel Houle

Joining us today is Taylor Scarr from the Canadian Forest Service. Taylor, how are you?

Taylor Scarr

I'm well, thank you.

Joel Houle

You have many years of experience dealing with the Asian longhorned beetle, which is an insect that feeds on certain types of trees. Can you explain to us what are Asian longhorned beetles, where they come from and why is there such an interest in them?

Taylor Scarr

The Asian longhorned beetle is a very large black beetle with white spots on its back — sometimes called the starry sky beetle because of that coloration. And the longhorned name comes from having these very long antennae that reach almost back to the full length of the body of the insect, and then some of the males that can actually be longer than the insect. The insects are large, robust fat beetles, and they attack hardwood trees.

They're native to Asia, particularly China, which is where the infestations in North America seem to be coming from. And these beetles attack several species of hardwoods. They really like maples, also willow, poplar, birch and 20 or 30 other species of trees that they will attack.  And they bore into the tree, the larvae bore into the tree, feeding under the bark and then move into the center of the tree. And that hollows out the wood, creates tunnels in the tree, and weakens the tree and eventually cuts off the water supply and the food supply movement in the tree. And eventually the tree dies.

Barb Ustina

Wow. Now, you mentioned that they're very large. I'm wondering if you can give me a sense of just how large they are. Would I recognize it in my backyard, if I saw one?

Taylor Scarr

You would probably be startled if you saw one because of the size and the black shiny body and the white spots on its back. We have a native insect, the white spotted Sawyer that looks similar. It's a black beetle with long antenna that attack conifers and it has a single white spot behind the head where the wings come to together. This Asian longhorned beetle though, is much larger, it makes a large hole that... the Americans compare it to a 45-caliber bullet hole, it's very, very large. And the beetle itself makes that hole as it tunnels under the tree. It's a round hole. Hence the name for this insect. It's also Roundhead Woodbourne. So think about a beetle that might be almost the size of your thumb in length — a very large beetle. When it flies, it has to lift its wings out of its way, the hard wings on its back and unfold a membranous pair wings underneath. So it flies very awkwardly with these hard wings held up out of the way and it flies on an angle. So it usually doesn't fly very far because it's such a large beetle. Normally it might fly, say, 400 to 800 metres and it finds the host tree within that range. It'll usually stop there and start to lay eggs or feed on that tree.

Barb Ustina

Well, it sounds like you could probably hear them coming from behind if they were coming up behind you. They're a very special kind of beetle. Where in Canada have you seen infestations of Asian longhorned beetles? And what kind of damage did they cause?

Taylor Scarr

Fortunately, we have only had one infestation of Asian longhorned beetles in Canada. There are other infestations around the world. The beetles have been invading other parts of world where they've been shipped to inadvertently. So there are infestations in in the United States — in New York, Chicago, New Jersey, in Worchester, Massachusetts, Boston, Buffalo, Ohio — major infestations. There are also infestations in Europe. There are around 14 or so introductions to Europe. And in all of these cases, the agencies are trying to eradicate or have successfully eradicated the insect from some of those infestations. The first time I saw this insect was in 1998 when it was found in Chicago. And that has been successfully eradicated. It was found two years before that in New York City and most of that infestations have been eradicated. It was found in New Jersey where it's been eradicated. It's also been intercepted several times in Canada. The first interception that I became aware of was 1998 in Waterloo, Ontario, where it was intercepted in a warehouse that was importing all the parts from China. But as recently as 2019, it was found in a warehouse in Edmonton.

The infestations in Toronto and Mississauga and Vaughn are the ones that have concerned us the most. So in 2003, the insect was found for the first time infesting trees in Canada, and that was in Toronto and Vaughn. And then there was an aggressive eradication program led by the Canadian Food Inspection Agency. It was declared eradicated in April of 2013 after five years of no positive finds and no infested trees. But then again, in August of 2013, it was found again, this time in Mississauga, and in some trees as well in Toronto. And it looks like that those two infestations are really the same infestation that the Mississauga/Toronto one that was found in 2013. It's a remnant of the original 2003 infestation in Toronto and Vaughn, probably from beetles that hitchhiked on a car or transported inadvertently to Mississauga.

Joel Houle

So they hitchhike on a car? How's that?

Taylor Scarr

So, they are strong beetles. They can hold on quite well. I mean, that's how they can fight off a predator. A predator goes to grab them, they grab on with their beak or with their mandibles. And when it was found in 2003 and again in 2013, in both instances, it was actually found by people who spotted it on a car. In both cases, different people, different vehicles, but the same detection method. And when we were doing the eradication program for the 2003 infestation, the last trees that were found infested were around 2007. And in most cases, those trees were found in the front yards next to driveways. And our suspicion is that those beetles were probably being picked up in the major infestation and transported inadvertently to people's homes. And then the beetles, once the car stops, the beetles fly off the car and go to the nearest tree that they can attack, particularly if it's a maple tree.

Joel Houle

So wow, they really are world travelers, I guess, hitchhiking on cargo and then hitchhiking on cars to go around. How do they normally spread, though? Are they a fast-spreading species or are they more slow?

Taylor Scarr

The introductions are usually by people, of course. It's usually wooden pallets, wooden crates that are used to transport goods, not infested wood like trees themselves. But also in trees, say, in a plantation in China where trees are growing for use in wooden pallets or wooden crates, or in the case of some trees being grown to reduce the desertification in China, the Gobi Desert. So they were planting trees that turned out to be host for this beetle. When those trees were cut and used for making wooden pallets or crates, they then inadvertently got shipped around the world in infested material. So if you're looking at something like auto parts, you're not as an inspector looking for beetles or fungi or other things. You think, well, it's auto parts, what we need to worry about. But it turns out that the material that the goods were being shipped in was actually infested. And so that really had to change the way we do our inspections around the world that don't just look for soil or plant material when you're doing inspections. Look at the commodity, not the commodity itself, but what is being shipped in to see it that's infested. So that's how the long-range transport can move this insect around. People can also move the insect around in things like firewood or pallets. People, if they take the pallets say from the city area, from an urban area and take it to their cottage and use it as a bridge for over a stream, that's how may actually be infested. Or if they take firewood. You know, you have a tree die in the yard and you say, oh, well, I'll take that to the cottage because I've got some free firewood. That material may actually be infested.

So the governments of Canada and the U.S. and around the world are all discouraging people from moving those kinds of infested materials and from moving firewood and saying you should buy it locally and burn it locally and not with firewood because you may be moving infested best material around. The beetles themselves, they can fly, as I mentioned, but they take a lot of energy to fly because they're big, robust beetles, so they don't like to fly very long distances. It also exposes them to the predators. They will often come out of the trees that they've infested. So the eggs are laid, the larvae feed underneath, the insect pupates inside the tree. And then one to two years later, it emerges as an adult beetle. They'll often just turn around and re-infest that same tree, lay their eggs on the bark and re-infest that tree. They will fly to other trees nearby. But most of the time, the catch and release studies that have been done in China and the analysis that we've done with the Canadian infestation in Toronto and Vaughn, and Mississauga and Toronto, show that the insect usually doesn't go more than 400 metres and rarely more than 800 metres. So with the infestations, when you go to manage them, what we did was we had a program of cutting down the infested trees. Then they were found through the surveys and then any neighbour within 400 metres in the case of the first infestation in Toronto and Vaughn, and at 800 metres in the case of the Mississauga/Toronto infestation, any host tree within 800 metres of the known infested tree was also cut and chipped because we know that the surveys can't find 100 percent of the infested trees.

Barb Ustina

I imagine that the first line of defence is at our borders, making sure the insects don't come to Canada in the first place. But we can't always stop that? So once they get here and there's an infestation under way, I imagine it's a bit like solving a mystery in that each infestation a little bit different. Can you tell me a bit more about the process our scientists used to eradicate this part?

Taylor Scarr

So the first step then is to do the surveys. Once you detect the insect, we need to do the limitation surveys to find out how large the infestation actually is and which trees are infested. So that involves ground surveys with trained observers that look for what are called over position pits, which is egg laying pits that the female beetle chews. And it's just the depression in the bark of the tree. And she turns around and leaves a single egg there. You can spot that because when it's fresh, it's likely coloured, then it darkens up a little bit as it ages. But you can look for those. You can also look for sap leaking from the tree itself, because infested trees often produce a lot of sap, which can attract butterflies and wasps and so on, because when the insect if feeding under the bark, the sap can be leaking out and that can attract these other insects. And the other thing we would look for are the exit holes, which are about a centimetre across in diameter. So we look for those and that tells us whether or not the insect has exited from that tree. That can be done both from the ground with trained observers looking with binoculars or just by eye.

We also have used tree climbers that climb right up into the tree. They're trained arborist tree climbers that climb up and look at all angles from above and below to see if they can spot the infestation in the tree. And also, we can use bucket trucks where you put a trained observer in a bucket that you lift up into the canopy of the tree and look for the insect in the tree, look for the exit holes, look for the egg laying pits and see if we can spot the insect. One of the things interesting that we found in doing this work, the science that the Canadian Forest Service was doing showed that a trained observer can usually spot in infested tree within about 90 seconds. If they walk up to a tree or they're looking at that particular part of the tree, if they are going to find the exit hole or an egg laying pit, they're going to find it within 90 seconds. If they don't find it within 90 seconds, then it's really unlikely that they're going to find it. Then they just move on and look at look at more trees. So then when the tree cutting comes along, we cut down that tree. We examine on the ground to see how heavily its infested. We take the tree back if it's infested, we cut it into pieces, take it back to a lab to determine when it was infested, how long, how many eggs relayed, how many eggs turned into adult beetles and so on. And then we also cut down the neighbouring trees and do the same kind of examination.

Barb Ustina

Now, it sounds like there was a lot of tree cutting and chipping going on, and people in Canada, we're pretty particular about our trees and vegetation. How did people react when they first heard about the decision to cut down the trees in an attempt to save them?

Taylor Scarr

Fortunately, we had the experience of what had gone on in the United States when this insect was found in New York and Chicago. And the experience there was that if people understood what was being done and understood why, then they would much more likely to accept that the trees need to be cut. And one of the key things was that, one, you needed to be showing that you're doing things to prevent these infestations, such as border inspections and controlling infested material coming in from other countries. And then when you're actually involved in an eradication program, if we're telling people that we're going to restore the site, plant trees again, essentially to replace the trees that are cut, then people are much more accepting of that. So there were a lot of public open houses and public meetings, media coverage, newspaper stories and so on to explain to people what the program was that was being done and why. And convincing people that, yes, that tree in that front yard or in that park is a beautiful tree, is an important tree. But if we let it be infested, then it is eventually going to die and you're going to lose it. And for the sake of the rest of the trees in that neighbourhood — for the rest of the trees in that city and for the rest of the trees in the province or that part of the country — then people were accepting of the fact that these trees need to be sacrificed in order to protect those trees as well as the industries that are affected. I mentioned this insect really likes maples. So had this insect been successful in escaping the Toronto/Vaughn and the Mississauga/Toronto infestations, then it could have gone out into the rural forest, into the contiguous forest, affected our hardwood species, really affected our maple syrup production and our maple hardwood industry, and also affected our trade. Because when you get one of these invasive species, if you don't take aggressive action to eradicate them and they get established, then other countries impose trade barriers on us and tariffs and non-tariff trade barriers to prevent us from shipping our material outside of Canada. So for those reasons, as well as the ecological impact of this insect, people were very accepting of this.

There were some people who didn't like the idea. Some people thought that we should be treating the trees with an insecticide injecting the trees, trying to keep the trees alive. But we opted to be aggressive and move rapidly when the first infestation was found in September of 2003. In Toronto, trees were being cut by November. It was a very rapid reaction, a very rapid response to get those trees as soon as possible to stop the spread of the insect. And by cutting the tree and chipping it, then we know it's not infested anymore and we know it's not going to harbor those beetles. So the Canadian action was to be really aggressive and sustained action to eradicate this insect.

Barb Ustina

Yeah, it's quite incredible that we were able to eradicate it like that. I'm wondering now that we've taken care of that infestation, what steps are we now taking to prevent future outbreaks?

Taylor Scarr

I mentioned that this insect was found in 2003, it was probably here several years before that, at least back to 1996 or earlier. And in that era then, that's when a lot of the inspections were focused on the commodity, not the wood material that was being used to ship material. Now, we've changed the way inspections are done in Canada and the United States and elsewhere to look for these other insects and diseases that might be coming in. And in 2004, the Canadian Food Inspection Agency, together with the United States and Mexico, because we often try to coordinate our efforts — those governments imposed new restrictions that wood materials such as wooden pallets and crates used to ship material from infested areas like China, that they need to be treated or treated with a fumigant before they arrive in North America to keep those invasive species out. And we've ramped up inspections and trained a lot of people in Canada Border Services and the Canadian Food Inspection Agency to watch for these insects and diseases. The provinces are doing the same. They have monitoring programs looking for invasive species. There are lots of agencies, non-government agencies that are involved in looking for these kinds of invaders to make sure they don't come in. And then formally, the Canadian Inspection Agency, for this insect in particular, it maintained an annual survey of various cities across Canada on a rotating basis to look specifically for Asian longhorned beetles to make sure that the insect hasn't arrived somewhere else and established. And that is still a risk, even though we've declared it eradicated this spring from Mississauga and Toronto. After five years of negative surveys and not finding it, it's still possible that it could show up somewhere else, that it's already established somewhere, or that it's been reintroduced somewhere or somebody has moved it. So we have to remain vigilant for that insect.

Joel Houle

Taylor, you've mentioned working with the U.S., with CFIA, CBSA, what other partners are you working with to eradicate the beetle?

Taylor Scarr

Whenever you get one of these major infestations, like the Asian longhorned beetle, they're usually so large or so significant that it's more than one agency can respond to on its own. This eradication of the beetle was a success because of the leadership from the Canadian Food Inspection Agency, the science that was provided by the Canadian Forest Service, university professors and the Ministry of Natural Resources and Forestry with the province and the cities of Toronto and Vaughn for the first infestation, and then the cities of Toronto in Mississauga for the second infestation. The cities provide a lot of the operational aspect of how to organize all the logistics of cutting down trees, chipping them, hiring the contractors, the tree companies, getting them involved, the arborist to do all that very heavy lifting and cutting of those trees and then also having the advice and involvement from the U.S. Forest Service, the U.S. Department of Agriculture, the U.S. Agriculture Research Service and their Animal Plant Health Inspection Service were all advisers to us on how to do this. And we benefited from their experience and from the involvement of all the partners, including the conservation authorities in the area, too. So all those people working together were able to carry out this very effective and I guess rapid in the sense that in both cases, most of tree cutting was done in a couple of years by five years of surveys. And very large program, very complex with all the partners working together.

Joel Houle

For our audience, if they would like some additional information on the Asian longhorned beetle or if they think that they might have spotted one, what should they do? Who should they contact?

Taylor Scarr

There are lots of options for people. The first option is the Canadian Food Inspection Agency that is on the alert and has the official mandate for this insect and other invasive species. The Canadian Forest Service, we have labs across Canada, in Victoria, Edmonton, Sault Ste. Marie, Quebec City, and in Fredericton, where people can contact them and get an expert to determine whether or not they have found the Asian longhorned beetle. The provinces likewise have their monitoring programs through their departments or ministries of natural resources that they can contact. There are several NGOs. In Ontario, for example, there's the invading species hotline operated by the Ontario Federation of Anglers and Hunters with the Ministry of Natural Resources. There's also the invasive species centre that can be contacted. So there's lots of people that are ready and willing and able and interested in helping people identify what they found. And that is how I think we're likely to find it, if it's established somewhere, is that somebody is going to report it after they themselves have detected it. Most infestations of this insect are found by the public despite all the surveys done by official agencies. Most of the time it's an alert person from the public that says: "That looks different than what I'm used to. Don't know if it's the native insect or the white spotted Sawyer or this introduced one. I'm going to check with someone and make sure."  And that's how I expect we'll probably find it if it's out there.

Joel Houle

Taylor, thank you so much for taking the time to come and chat with us about the Asian longhorned beetle and keep up the good fight.

Taylor Scarr

Thank you both. It's been my pleasure!

Barb Ustina

Thank you.

Joel Houle

It's good to know that the beetle has been successfully eradicated in the Greater Toronto Area.

Barb Ustina

For sure! I guess it helps that it’s an insect that can’t fly really well, and is pretty happy to stay put as long as it has enough to eat. In any case, it’s pretty unusual to actually eradicate an insect. So this is a huge accomplishment. It’s comforting to know we have scientists and experts like Taylor Scarr who are on the case, and ready to take action if this pest ever shows up again.

Joel Houle

Definitely. For our audience, if you guys want to learn more about the Asian longhorned beetle, make sure to check out the links available in the episode description. You can also leave a review or share this episode. And if you share over Twitter, make sure to tag our new account @NRCanScience. You can also tag our personal accounts. I’m @JoelScience…

Barb Ustina

And I’m @SimplyScienceB, that’s the letter B. I might remind everyone that Simply Science also has a website and a YouTube channel, which you should check out. We have in-depth articles of interest and videos that showcase the fascinating scientific work that we do at Natural Resources Canada. And you can find those links in the episode description as well.

Joel Houle

Thank you Barb! I think that’s it for us today. Thank you so much, everyone for listening! We’ll see you at the next episode!

Barb Ustina

Bye!