University Place

Brad Herrick

Thank you very much again for coming to this seminar. It's a really, it's an honor to be back at the Garden and Landscape Expo in front of lots of other earthworm enthusiasts.

audience chuckling

laughs

Brad Herrick

Yeah, exactly. So today we're gonna be talking about everyone's favorite topic, invasive jumping worms, and I'm guessing since you're at this session, you either heard of them, you talked to neighbors that might have them. You might have them in your gardens. So we're gonna talk a little bit about kind of what earthworms are, talk about some basic biology and ecology about them, how they can transform the environment, especially the soil landscape. We're gonna dive into how to identify them, which is always kind of a barrier to understanding different earthworms, but also these new jumping worms, and then spend most of time talking about these Asian jumping worms, that are relatively recent invaders to the Midwest. And again, so my name is Brad Herrick, and I'm the ecologist at the Arboretum here in Madison. And I've been working with these earthworms for about seven years now, since they were first reported at the Arboretum, which was the first confirmed case in Wisconsin. So let's dive into some background. This will be a crash course in earthworm biology. Earthworms, as most of you probably know, they live in the soil or within the litter and they feed on organic matter, either organic matter that's in the soil or organic matter in the form of leaf litter usually. They are promiscuous, they are polygamous, hermaphroditic, and often in the case of jumping worms, they are parthenogenetic, meaning that they don't need a mate to reproduce. So in theory, if you have one mature adult jumping worm, you could have a population soon, 'cause they don't need a mate to reproduce and produce cocoons. A lot of grumblings, I know, I know. That's why they're such good invaders. Okay, so there's different types of earthworms, and we divide them into different functional groups, basically based on where they live and feed in the soil horizon. So the first group are what are called epigeic, and these are earthworms that really spend most of their time above the soil in the litter layer, and that's predominantly what jumping worms are. At least the ones that we have in Wisconsin. On one hand, that's a good thing, because they're easy to find, especially in the middle of the summer during the growing season, they're gonna spend most of the time in that litter layer. Then they're sort of this intermediate group called endogeic, that are usually in the soil but just in the top few inches maybe of the topsoil. And then there's these deeper ones called anecic, and these are, a good example of these are the common night crawlers that we're all familiar with, used for fishing bait. Those guys go really deep into the soil, and they actually can overwinter under the frost line. So they can survive our winters as adults. So I mentioned jumping worms are primarily litter, litter habitat. They can also span to go into more intermediate. So we refer to jumping worms as epi-endogeic. They kind of span that little horizon from the very upper soil to the litter. So that's where you're gonna find these guys. So there's been a lot of work done, a lot of research done on European earthworms, which is what the common night crawler is. And how they can change their environment, especially in forests. One thing to mention before I go too much farther is that all earthworms in Wisconsin are considered non-native. There are no native earthworms to any glaciated parts of North America. So the night crawler, these invasive jumping worms, they're all from either Europe, parts of Asia. We have some from New Zealand called yellow tail earthworms, but they're ubiquitous now. They're sort of "naturalized" or they're everywhere, but they do have impacts. They have different impacts to our garden system, which I'll talk a lot about obviously, but when they get into natural systems like these forests that did not evolve in the presence of earthworms, they can do a lot of damage. And so on the left-hand side, you see a really healthy, intact forest system with lots of native understory plants, healthy root system to trees, and really a differentiating of soil profile, from the real duff, spongy layer to more the unconsolidated mineral layers. If you go into a woods that has a lot of different earthworm species, high abundance, they are churning that soil. They're mixing it really quickly. They're compacting the soil. They're reducing all that spongy organic layer, and why that's important is that tree species, herbaceous plants, especially young plants, need that organic layer because it's full of moisture, kind of like why we compost, full of nutrients, to help them germinate and then persist. Without that, few native plants will do well, and there's been a lot of research done on kind of a feedback loop, where other invasive plants like your buckthorn, garlic mustard, can do really well in that highly disturbed environment. And so you get these ecological engineers moving through the soil, these earthworms, and they're changing fundamentally the soil profile, and that allows species that we don't want to be there as well in terms of plants to come in, and they have their own impact. So they're sort of the canary in the coal mine, if you will. If you're seeing these in these nice habitats, potentially you could have bigger problems down the line. And again, this is in, these are in forest systems, but this is to give you kind of context for what's been studied in terms of earthworms. I'm not gonna go through this slide in too much detail, but I mentioned that earthworms are considered sort of ecological engineers that can really change the habitat where they are introduced, through how they burrow, their casting behavior. So castings are their excrement, when they are eating organic matter, they are producing excrement that are high in nutrients. How they feed, mucus, that chemistry in their slime basically. And they can have physical changes on the soil structure, chemical changes, and then also impact other organisms. Invertebrates in the soil, bird nesting habitat, all sorts of things they can change. All right, so now you're all experts on earthworms. So you're up to speed. Now we're gonna dive into what are these jumping worms? How do they differ from other earthworms that we might see in our gardens? And then why should we be concerned? Why are they a problem? And some of you can probably already answer this from your own experiences. So as I mentioned, this group of earthworms are native to Asia. So primarily Japan, the Korean Peninsula, areas of China. Interestingly, they're commonly found in grassland habitats where they're native to. And I'm not gonna get into that too much, but we have not found these earthworms in prairies. They have been found in turf grass, but usually near to garden habitats that have mulch and that sort of thing, and they just have expanded out into those areas, but there's more research that needs to be done about why they're common in one habitat, where they're native to and why we find them in other places here. And there are of course hundreds of species of these earthworms worldwide. We just have a handful in North America, and only three have been found in Wisconsin, but they're all very similar in terms of their habitat, and how they look. I mentioned earlier that the first record in the state was in 2013. Now, they've likely been here longer. We just didn't know about them or weren't looking for them. And so the first confirmed record was in 2013, just a few miles from here. And Wisconsin has a unique program at the DNR, where they track invasive species of any sort. Plants, animals, fungi. And so currently, this group of earthworms are listed as restricted in the state. So that means that they were listed as prohibited until we found them, and of course that changed, and so now they're restricted, meaning that in terms of regulations, you still cannot sell them in the state, you can't knowingly you know, move them across state lines, you can't you know, knowingly introduce them places that don't have them, but there's no restriction on having them on your property, because they're very common now. I know, it's funny that you could even think about.

all laughing

Brad Herrick

And as you'll learn, we don't have a silver bullet control. We have more options now, but we don't have that one control that we can share with folks that can get rid of them at the moment. There are three species. I'm not gonna talk about these in depth because they're all very similar. The genus is Amynthas. And so, there's tokioensis, which are somewhat small earthworms, maybe three inches. Amynthas agrestis, which are kind of the intermediate, maybe five inches, and then there's is one, which is called Metaphire hilgendorfi, which is 8 inches, 12 inches.

audience exclaiming

Brad Herrick

I know, that's always the response, well done.

audience laughing

Brad Herrick

And, but they're all similar. They're all epi-endogeic. They all play in that same soil profile, in the litter, topsoil, and they're all parthenogenetic, okay? All right, so here's how you can arm yourself with information about what to look for, and it's February, these are annual species, and so you won't be finding them now, but in the spring in a couple months, this is what you can start to look for in terms of what you have on your own property for earthworm diversity. So I'm comparing Amynthas generally with a very common European earthworm called Lumbricus rubellus, the red worm. And I'm doing that because these earthworms can be found in the same soil profile. The Lumbricus is also sort of that epi-endogeic earthworm. So you might find them at the same time potentially, and so knowing what they look like and how to differentiate can be valuable. Generally, Amynthas will be larger than Lumbricus rubellus. Size is always a really kind of poor indicator, because environmental variables. Your particular site might have more nutrients, might have a different kind of organic matter that allows earthworms and other organisms to be larger or smaller than average. So take that with a grain of salt. That's not the best indicator. There are better ones, and I'll talk about that here shortly. I mentioned the life cycles are very different. This group of invasive earthworms have an annual life cycle. So they do not survive as adults over winter. Right now, they're in little cocoons under the soil or within the soil, under the snow. Lumbricus, so, Lumbricus is a group of earthworms from Europe, Lumbricus rubellus for example, can burrow into the soil and can overwinter potentially. They can also produce cocooned, and they can overwinter as cocoons, but in the early spring, you're gonna find earthworms right away that are large. Those are not jumping worms. Those are European earthworms. Jumping worms have to hatch from cocoons. They're really tiny, and it takes them 70 days to actually grow to any size that you could identify them. So that's a common question that I get is, "I'm seeing earthworms in April. "They're everywhere. "Are they jumping worms?" And more than likely they are not, unless you have a really weird microclimate next to your foundation that stays warm all winter or some kind of exhaust or heat source that's coming out that can warm that soil and keep it warm all winter, but early earthworms are gonna be something different from jumping worms. The coloration is a bit different. Jumping worms have kind of a two-tone color on their ventral side or their backside, which is what you're gonna be seeing generally. It is darker than their tummies, which is more of a pink color. Other earthworms are generally the same color throughout their body, and there's a reddish brown. And the other aspect of their skin that you can actually feel is that jumping worms have a much more rigid body type. Other, lots of earthworms have sort of, I don't know what the word is, but they will kind of wrap around your finger. They're sort of flaccid if you will, whereas jumping worms are very rigid, and there's a consequence of that, and I'll talk about that in terms of their behavior. One of the structures of earthworms is this little ring, and that's what these arrows are pointing to, and that's called the clitellum, and that's the reproductive area of the earthworm. That's where they're producing cocoons and offspring, this little ring near the head. Jumping worms, when they're adult, this is a great ID characteristic. They produce a white, kind of milky gray ring near their head. All other earthworms have clitellums too, but they're the same color roughly as the rest of their body, and you can see that illustrated here. Also there, that ring on the jumping worms is smooth. So you rub your finger over it, and you can't tell that it's there. It just feels like the rest of the body. It's not raised. It also goes all the way around the body, okay? So those three characteristics, color, texture, and the fact that it goes all the way around, it's annular, around the body, is different from any other earthworm. If you find a common night crawler and look at that little bump near the head, that's the clitellum. It's raised off the skin, and if you turn it over, it doesn't come together underneath. It's like a saddle, okay? So when they're adults, that's probably the best way of telling them apart. If you want to really nerd out and buy a microscope, I have many. I can lend you one. You can count the number of segments from their nose to where that clitellum begins, and it's consistent within species. So clitellum on jumping worms form on segments 14 to 16, clitellum on other species are much farther down from their nose. You don't have to count the segments to see this. You could find both worms and see that one clitellum is maybe a third of the way down the body, and one is really close to the head. That's the method there. The behavior, and if you've seen these and I'll show you some video here in a moment, the behavior is really creepy.

audience laughing

Brad Herrick

But it's a good ID, it's a good way to tell what you have. So they're very active, and that's because they have this rigid body, and so they're able to really snake, snake around. They can literally jump in your hand. They don't have legs. They don't have arms. They're not jumping literally, but their movement is so erratic and so energetic that they can bounce around. Other earthworms aren't doing that. They're kind of wiggly, right? You've all seen earthworms or held them. They can wiggle, but they're not actively flopping around on your hand. That's a great way to tell what you have in your yard. Or another good way, and you actually tell this in the wintertime, is to look at your soil. So I mentioned earlier the casting behavior, and this is the earthworm excrement that all earthworms make, but they produce different patterns of excrement laying. And so, these jumping worms will lay kind of a uniform, coffee ground, very loose casting. So they look just like soil, but if you have them, you can see it, and I'll show you some photos here what that looks like. You can see the changes in the soil. This loose, coffee ground-like soil compared to little piles of castings that other earthworms will make, okay? Kind of random in nature, not universal. And then another creepy feature of these is that they can drop their tail when they're being aggravated. They will just, they will drop a few segments of their tail as we think a mechanism to escape predation or something. Other earthworms will not do that, okay. Now after this slide, I think we have some video. So here's a good example of what the soil looks like. So the left side, and I don't know if it shows up well enough, but the left side is with species of jumping worms. You see that really uniform, granular looking soil. Other side is without, and this photo was taken many years ago now at the Arboretum, right at the invasion front. So we've been mapping the invasion of these earthworms throughout the Arboretum over the years. So this was one photo that I just drew a line between, and you can see they're moving left to right, and now the right side looks just like the left side. Okay, all right. Let's see if this will work here. So here is an example of jumping worms. Again, right on cue, well done, same reaction.

audience laughing

Brad Herrick

How about again? Let's see it again. Now I have to admit that we collected earthworms or jumping worms and put them there. And so they are already unhappy with us. Show that again, there we go. So that's that behavior, that really wiggling kind of snake-like. And then here is a video of that snake motion, a little more in detail. Now can you pick out the white clitellum on this one? So see if you can see, find the head and find that white clitellum, there we go. Right there, right there, yeah. Okay, all right. Now I mentioned that they can drop their tail when they're angry at you, to try and escape predation. So here's one, it's kind of a young one. You see that on the right-hand side? The tail is sort of moving independently. There it goes, and it's still moving. Now I will get questions about if you cut an earthworm in half, do you have two earthworms? No, no, so that segment is just, it's just moving because it's a creepy organism, and it's just adding to its reputation. But it doesn't create two earthworms. Remember, the reproductive area, the nervous system, so to speak, is still intact. And so that earthworm can still produce offspring that has a clitellum still. But this is just a mechanism that you might see, and it's a trait of this particular earthworm. Now, it could be worse folks, okay? This is the Giant Gippsland earthworm from Australia. It's native to Australia, and it can be five, six, seven feet. You know, looks like a long sausage just out of the sausage maker. I found this photo, and it doesn't really relate to what we're talking about. But boy, is it a cool photo.

audience laughing

Brad Herrick

Look at that. Earthworms are amazing, just amazing, but if I saw that one, I would probably literally run the other way. That is incredible. And she looks somewhat thrilled to be holding that.

audience laughing

Brad Herrick

All right, so back to where we are. So there are different-sized jumping worms, right? We talked about that. Well, they produce different-size castings. Now this is sort of academic in a way, but you can tell by the size of the particles that you might have in your soil, what species you have. So they range from the large ones, the Metaphire, larger castings to the smaller ones, the tokioensis, which produce smaller casting, just given body size. Again, that's academic in a way. If you see, they all produce it uniformly. It's all kind of coffee ground-like loose soil, but just so you know, there are different species that might produce different-sized castings. These are cocoons, okay? So we've isolated, a lot of our research is focused on this part of the life cycle 'cause we think we have, we're able to maybe interject some control over how they produce and if we could control their hatching, we might be able to think about reducing populations that way. Their cocoons are very small. They're two millimeters in size. They look just like soil particles. They're really next to impossible to actually see in the soil. And so, I mean they're not microscopic, so you can find them, but we go through a wet sieving process to isolate the cocoon from the soil, but just so you know that this is one reason why they're so, they're doing so well in terms of a species and invading is that they produce these cocoons, and they're impossible to see in the soil. And so you know, how easy would it be to step on soil. You have these, are attached to the soil on your shoes, on the tires of your car. All you need is one cocoon with one earthworm into a new area and you potentially have a new population. So we're actually less concerned about transporting the earthworms and more concerned about these offspring, these cocoons that you know, once they're in a new area, can produce a new population. I mentioned that in the spring when these are hatching, you're not gonna see them in the soil for a while because for one reason, they're really tiny. So this is a brand new baby jumping worm. They're about 10 millimeters in length, and again, you can find these in the woods. They're often gonna be in leaf litter, and if you go through in April or May when it starts to warm up, you can find them, but they're not easy to see. The one thing to note about this is that when we first started looking at jumping worms, we were seeing lots of little white earthworms in the early spring that kind of had a similar behavior. They're really kind of wagging at us under the leaf litter, but they were white, or sometimes kind of translucent, and we thought that those were maybe the new hatchlings. They are not, those are called pot worms, and many of you maybe have heard of pot worms. They're actually not in the earthworm family. They're native as far as I know, but they're not harmful to anything. They're ubiquitous, they're everywhere. Earthworms when they hatch, are pigmented from the beginning. So if you see a tiny earthworm in May, April, that's pigmented, that might be a jumping worm. It can also be a European earthworm. It could be a lot of different things. So at this stage, even I can't ID these kind of earthworms. And so it does take a while for them to mature before you can differentiate with some of those traits we talked about, but if you see adult big earthworms, again in April, May, those are not jumping worms. There's something that has overwintered, and it's just come up when the soil has warmed. All right, so why should we be concerned? We talked about earthworm effects on forests. They reduce litter layer, all that good nutrients in the soil. It can affect, especially if you're a native gardner or if you're working on land that you're restoring, that can be troublesome to get native plants to establish. They really change the soil dynamics, and we think that the effect of Amynthas or jumping worms will be similar to what we've seen with European earthworms or even more, because they are parthenogenetic, very easy to spread with those cocoons. Now, let's change gears here, 'cause you're all thinking, "Wait a minute, "I've heard my entire life "that earthworms are really beneficial for gardens and for my soil. "So isn't that true?" And the answer is yes and no of course, 'cause not everything is black and white, and there's always some nuance. So let's talk about urban gardens, and you know, many of you probably live in the country and have more of a rural setting garden, but many of you maybe live in urban areas, and have a smaller backyard garden like I do. Urban gardens especially, and we talk about large-scale Ag, have very compacted soils generally. If they've been worked a lot, they need amendments. I know my garden is basically on fill soil here in Madison, and so it needs amendments, nutrients. It needs amendments in terms of holding moisture, and one of those amendments can be earthworms, and earthworms can do a really, can provide a really great function in terms of reducing soil compaction, creating burrows to allow air to get to the root system, to allow water to get to plant roots. And so they can provide a really nice system, especially for annual garden crops, even perennial vegetable crops. And they eat lots of organic matter, we talked about, and I mentioned earlier that those castings, their excrement are really high in nutrients, and so that can be really beneficial. You can buy earthworm castings as nutrients to help enrich the soil. And because they're found with, they have a lot of these nutrients, plant nutrients. However, jumping worms behave much differently, and one of the ways that they behave differently is that remember, they only do their work in the top inch of soil plus the leaf litter. So they're not going down in the soil. They're not effective at aerating the soil or mixing the soil profile. They're not effective at providing more infiltration to that root system, and in fact, they may create too much porous space in that upper layer of soil. Remember those castings that we talked about are really loose, and so they're not holding much moisture, and so they can actually have the opposite effect. They can dry out the soil, especially on the top, which can be a problem for annual species or seedlings. And then, jumping worms can create a really loose topsoil, which is also highly erodible. If you think about coffee grounds on the landscape, you get a heavy rain, and if you're on any sort of slope, which we've seen at the Arboretum, you'll lose that soil very quickly. So again, soil may be too loose for plants to establish. I've heard lots of people talk about even plants like hostas that are relatively hardy, they notice all of a sudden in the last couple of years, that has correlated with what they've found for jumping worms, that some of their hostas and other hardy plants are starting to kind of die back or not be as successful each year. It could be from jumping worms. It could be from any number of things frankly, but jumping worms, there is a correlation there. And what we've found is that jumping worms can, they turn over the litter so quickly, 'cause of their high abundance, that they can actually act like a quick release fertilizer. They turn that nutrients over. They create nutrients, but it's often too quick for plants to take up, and if we get a heavy rain, those nutrients are lost from the system. They're either eroded away or again, they're only being produced in the top layer of that soil or on top of the soil. And so they're not being distributed along that soil profile. And one more thing to add here is that jumping worms are most abundant later in the summer, okay? When plants don't necessarily need more nutrients in their root systems, especially perennial plants, perennial plants need that early spring flush of nutrients to germinate, to produce flowers and seed and fruits; they don't need it necessarily later in the year, when they're thinking about overwintering, putting carbohydrates back in the roots, but that's when jumping worms are producing lot of nutrients, and so they're actually depleting the soil of nutrients at that time of year, washing that away, which come next spring, will be a problem for some of the plants that the nutrients aren't available when they need it the most. And we've seen that they can just destroy turf grass, and even eat plant roots at high abundance. Now, not all plant roots, but some of the grasses that we have, turf grass being one of them. They can literally eat the roots where you can just take up a carpet of lawn, 'cause there's nothing there to hold it anymore. So how are they spreading? One of the ways, one of the main ways is through compost. Compost, hardwood mulch, okay. That's what we've seen. Here's compost, and primarily because these are high organic matter sources. And they're distributed far and wide from buying a bag of mulch, landscaping, municipalities are landscaping right-of-ways for obvious reasons. We all need mulch for our gardens to retain moisture, but that's a perfect habitat, perfect food source for these particular earthworms. You know, when we rake our leaves in the fall, many municipalities have a leaf collection service, where you rake them to your median or the road, they'll come and and pick it up. They will often redistribute throughout the city or provide a central location where folks can come and grab free mulch, bring 'em you know, spread far and wide, cocoons could be in there, earthworms could be in there. Again, these are all potential mechanisms for how they could spread. Things like plant sales, sorry to say, and there's been a lot of talk about if you know, garden clubs, other societies that plant sales are a really important part of raising funds to continue their operations, and there are ways that plant sales can still go on, and I think, I always advocate that plant sales do go on, 'cause they're a great way for people to, they're a great socializing event, they're a great way to get plants relatively cheaply, but one of the things we've done at the Arboretum, we have a native plant sale, is that, we've put restrictions on folks bringing in plants from their yard. That's one of the ways I think that they could spread is through plant sharing, and if you don't know if you had jumping worms and you are digging up you know, if they're hostas or native plants in your yard, and bringing them to a central location, if they're infested without you knowing about them, someone buys them and brings them to Green County or Rusk County, and that's just one way that they could spread, so for us, we've kind of stopped that practice, and we just purchase them wholesale from nurseries that we work with and that know about jumping worms, and we've been in and I inspect them, so now part of my job here is to educate folks like you about what to look for, and all I do with these is look at the soil surface. Is it granular? Is it intact? If it's intact, that's the best that we can do, and it's likely that those are gonna be fine. And I'll talk more about that here in a moment, but again, they're just potential ways that they could be spread. This is good habitat, greenhouse, nurseries, lots of organic matter there, landscaping companies, landscapers yourself, working in managed areas. Check your boots, check your equipment, tires, those sort of thing. These are general things for all invasive species, but that's how especially cocoons attach to soil on the tread of shoes or vehicles, shovels, they can spread that way. This guy is spreading 'em all over the place. Fishing has always been a source of earthworm spread generally, and the DNR had a long-standing campaign to discard your bait. Don't just throw it into the lake or into the forest. That's how earthworms can spread. Again, it's illegal to be selling jumping worms in the state, but they are for sale other places. Even online, so again, it's hard to regulate all this. We did a survey in the city of Madison. We just wanted to know where jumping worm was found, where were they not found, and so what we came up with, what we found was that, and we surveyed hundreds of habitats from prairies, woodlands, people's yards that had gardens and turf grass and then just city parks that had lawns. What we found was that jumping worms were found in all the habitats except for prairies. I mentioned grasslands, think of a prairie as the grassland. They're not found so far in like a prairie system with native plants. It doesn't mean that they couldn't survive there. They're just not found there yet, but they're found in gardens and lawns, especially gardens that have been treated with wood mulch, which is most of our gardens. And so that again, it's a correlation that jumping worms like that kind of habitat, and then this is where we found this new species of earthworms that's larger. The Metaphire one. All right, so let's get into what can we do?. So with the DNR, we've talked about you know, what can we share with the public about what actions we can take to actually mitigate the spread or get rid of these earthworms altogether. And when we started this about six years ago, there wasn't much data on really basic biology and ecology questions about this particular family of earthworms. We know a little bit more now, but there's a lot more that we don't know, and it's hard to come up with management strategies if you're still learning about the biology of the particular earthworm. So like most things, the need for knowledge and the need for actionable control items is outpacing the research. That's just how these things go, and so we're trying to catch up, but we do have some practices that we are sharing that really goes for a lot of invasive species, but a couple of these are specific to jumping worms. First of all, just look for them, okay? Understand what they are, and being in this session is the first step of educating yourself about what jumping worms are, and then look for signs of their presence. So look for those casting layers. Is the soil looking different here? Something's going on here, it's not right. Look for jumping worms themselves, especially during the growing season, like they're right at the surface. So if we've had sort of an average moisture year, they're not gonna be going down too far, 'cause they're gonna be happy in that litter layer or that organic matter layer. Again, educate yourself on what to look for. This is a good first step, and this way you can also educate your friends and neighbors as well. Some of these might sound challenging to do. This one here, only use, sell, plant, purchase, trade landscape and gardening materials and plant that appear to be free of jumping worms. Well, how do you do that in the real world? Well, it's not always possible, we admit, but when you, one way that you can think about this is if you're going to a nursery for example, and you're looking at potted plants, you can ask them. So nurseries, landscaping companies in Wisconsin especially, they know about jumping worms. If they've never heard of them before, that's a problem. And so it's in their best interest, and again like, we developed these guidelines with the green industry. And so they're at the table, they're very interested in not having them in their products. And so just asking asking the question, "Do you know about them? "Do you have them?" And they should be able to provide an answer. Again, look at if you're buying potted plants, just look at the plant. Does it look healthy? Look at the soil, is it intact or is it really loose and granular? Those are some things that you can do to release, reduce the impact that you might be purchasing something that is infested. And then again, only sell, purchase, or trade compost that was heated to appropriate temperatures and duration following these protocols. Again, that almost seems more difficult. How do you know that? Well, so in Wisconsin, and in actually over 35 or 36 states in the country, they have the exact same compost standard. So if you're a commercial composter in Wisconsin, you are required to heat your compost piles to a certain temperature for a certain amount of time, and that is to reduce the probability of having harmful pathogens and fungi in that compost. We know now that some of the work that I and my colleagues have done at the Arboretum have shown that the temperatures that the statutes are aiming for with the compost, those same temperatures will render the cocoons non-viable. So they'll kill the earthworms quickly. I'm talking about like 131 degrees Fahrenheit. That's what the standard is. At that temperature, cocoons will not survive. The embryos don't survive, and so in theory, if you're buying compost that's been produced by a commercial composter in Wisconsin, in theory that should be earthworm free, and cocoon free. Now, there's a big caveat here, is what happens from the treatment pile to when it gets bagged? There's a whole process there from backhoes picking it up, bringing it somewhere else, maybe putting it down somewhere else in a factory or a warehouse, or all sorts of ways that that compost could be re-invaded with cocoons. Again, that's something that we can't do anything about, but again, the green industry is aware of this problem, and they definitely are trying to you know, do their part to not have their products infested. And so, and again, like if you're, so if you're buying bag compost from a company from Wisconsin, I'd feel pretty good about that. The other thing that you can do is produce compost on your site, you know if, knowing your yard well, if you have them or not, if you can produce your own compost, keep your leaf mulch on site, reuse your mulch, then you know that what you're putting down is free of these critters. And I mentioned as well for any invasive species, this is a good best management practice. Arrive to your garden clean, if you're going to your friend's garden, to your community garden, make sure your equipment is clean. When you leave, same thing. Clean your tools, clean your shoes. Simple things, but these really do have an impact, and it's the same message for garlic mustard, for all these other invasive species, arrive clean, leave clean. So how do you find out if you have them in your yard? Well, now you are experts on jumping worm ID. You can tell, you can look for casting, look for the actual earthworm. You can also do a quick and inexpensive sampling this coming summer. There's a sampling called, basically it's mustard, it's using mustard solution to sample earthworms from the soil. This is actually a research method that's been used in the scientific arena for a long time. It's been used by K-12 teachers to teach their kids about earthworms. It's really fun and inexpensive. So what it is, is mixing 1/3 cup dry mustard powder with a gallon of water, and this is mustard powder that you can buy in bulk. I order it by the 10-pound box from restaurant wholesalers. I use a lot of it, so really doesn't have to be spicy, fancy Dijon mustard, just your typical yellow mustard. When you get to an area of your yard that you're concerned about or interested in, remove as much as you can of that leaf layer to get to a, just get to the soil surface. Pour half of the solution, a third of the solution, and again, since these are the jumping worms are at the surface usually, you're gonna get them quick if they're there. Now also, if you're interested in earthworms, any earthworm will react to this solution, not just jumping worms. So you can pour the whole thing in, let it infiltrate down into the lower layers, and you'll get deep-dwelling earthworms that will come to the surface. It might take a minute, but they'll come if they're there, and then you can collect them, you can see how many you have, if you have jumping worms or not. This is a great way, a quick, inexpensive way to do this. It's potentially a control as well. If you know that you don't have them or you're wondering about an area, if it's a small scale, even the size of this table up here or this podium, this is a way that you could just physically remove them from the soil. If you have a larger infestation, this is not the way to do it. You're gonna spend hours and hours and days. Your chiropractic bills from your back hurting will be extensive, but it's a way that you could at least get a sense for what you have in your soil, and then maybe employ some other mechanism that we'll talk about here in a moment. So here's an example of what that soil pour looks like. We've cleared away some leaf litter in one of our forests at the Arboretum. Okay, so we've mixed the solution up. We're pouring it over the soil. Now watch what happens quickly here. Do you see 'em?

audience murmuring

Brad Herrick

See the clitellum? So those right away you know are jumping worms. They came fast, and they were adults with that white clitellum. Now what's happening there? Well, all that's happening is that the mustard is irritating their skin. Earthworms kind of breathe through their skin. There's lots of pores in their skin, and so think of it like after a heavy rain, you see earthworms kind of scattered around the sidewalk. It's sort of like that. We're just sort of accelerating the process. We're mixing a little spice into their water and it doesn't hurt them, it doesn't kill them, unfortunately. It also doesn't hurt the plants either. So it's a benign way of testing for if you have earthworms. Other critters like slugs also don't like it. So they'll come you know, soft-bodied, whether they're earthworms or other potential invertebrates may come to the surface as well. It doesn't hurt them, but it is a fast way to tell if you have any earthworm, especially jumping worms. So in terms of what else we can do. So there are some potential controls if we start with chemical and physical controls, some of you might have heard of a product called Early Bird. It's been out there on the market for quite a few years, and it is a fertilizer first and foremost. That's what the label is for. It's an organic fertilizer that has this byproduct of the tea seed tree. And this is a tree from China that is high in this chemical called saponins, which are really common plant compounds that are used as a defense for plants against herbivory from insects and other fungi that might attack them. Most plants have these saponins. Some just have a higher concentration of them, and these saponins have been shown to be lethal in some dosage to earthworms. Any earthworm. And so this product has been used for a long time in the golf course industry as a fertilizer, but also as an earthwormicide if you will, 'cause golf court managers do not like earthworms that create these little casting piles on their greens or their fairways, 'cause that's not good for golfing. You can't have a bumpy fairway. So there's been a little bit of research looking at does it work on jumping worms? It does, but there are a lot of caveats here, and it's something that we're researching now in our lab at the Arboretum. One of the things that we don't know about this product is that what does it do to other, possibly beneficial soil biota? One study has shown that it doesn't really impact much in the way of some of the common soil biota like springtails and other species that you might find, but that's one study, and there's a lot more to do. So I don't recommend using this as like a large-scale control, but if you have some of this product, you could use it on a small scale. It comes in a granular form and a liquid form. Again, we're doing research right now on the ratio in terms of dosage, it's very expensive to buy, and before I go too much farther, the company recently had discontinued manufacturing it because of tariffs with China, it's becoming very expensive to bring in the products, and it was being, this use was kind of an off-label use. It's a fertilizer and not an insecticide. So at the moment, you can no longer purchase it. Now, the only thing is that really what we're looking at is the saponins. This was just sort of the vehicle to put saponins into the soil. There is research happening now on other potential saponin sources like alfalfa, and some of you might know some plants that might be good ways to, of sort of isolating these saponins and putting them back in the soil that might have the exact same impact. This is a very expensive product to use and again, there's lots of nitrogen that you're putting back in the soil that you may or may not want. So I think this still has potential control, but it may not be in the form of this particular product. So this is something that we're working on just you know, that using these natural plant defenses might be a way of reducing earthworm, adult earthworm abundance. Biochar is something that people probably know about. It's a carbon amendment into soil. You can buy it in nurseries and plant stores. And there's some literature out there that biochar will reduce earthworm populations just through the sharp granular biochar that will kind of tear up the earthworms' insides, when they consume it. It may or may not work for jumping worms. Jumping worms and all other earthworms can avoid biochar by just moving laterally. If it's mixed into the soil, they may not be able to escape it as well, but there's not a lot of research right now on biochar with jumping worms. So when I give these talks, I kind of asked, I asked for folks to try some of these products on their own garden system or back 40, where you may have jumping worms and let me know if they work. You know, there's not enough researchers doing this work. There's a lot more people gardening and applying some things and trying different things to get rid of jumping worms, and we can really learn from each other. I mentioned one of the things that we're working on in our lab is heat, and I mentioned that compost heated to 133 degrees, 131 degrees will work. Even lower temperatures at 104 degrees Fahrenheit will kill earthworms, will kill their cocoons. Now, so we know that these composters are heating it to well above that. So we've already established that that will work. And I think it's three days I think is actually more than enough. I think maybe for four or five hours would probably be enough. We haven't studied that, but I think a much shorter time span could be needed. So the question is how do you apply heat to your garden on any scale? I don't recommend fire, but we know that fire will work. If you're managing your savanna for instance, or your forests prescribe fire. Interestingly, did not have an impact on the adult earthworms because they can go down into the soil. Soil is a very good heat buffer, but the cocoons can't move. The cocoons are what we're focused on right now. They're not able to move. They did see a significant reduction in their ability to produce earthworms after just a really low, a low, creeping fire. And we found that with 104 degrees Fahrenheit. So other ways of applying heat in your yard, we're thinking about things like solarization. So putting down a clear plastic over some areas of your garden before the spring, if you're, this will only work if you have the right sort of garden without a lot of shade, maybe good south-facing sun, but it can heat up fast. Use clear plastic instead of black plastic. It actually heats up more, and these are things that we're kind of interested in experimenting. Does it kill the cocoons and do you see them in that area the next year? We've talked about using propane torches, finding a way to steam, sort of sterilize parts of your yard. Again, these all have other impacts to soil biota. But we know that this will work for jumping worms 'cause they're at the surface. So it doesn't take a long amount of time to apply that heat and impact earthworms and cocoons. We know that heat will deal with the cocoons, and that's the important thing, 'cause I think that's what we're talking about in terms of spreading these things really easily through cocoons. Other things to do outside of heat would be think about either reducing your mulch. Again, that's not always possible and I understand that, but the mulch is the food source for this invasive species. So the more you apply, the larger the buffet for your earthworms, and they're not gonna go anywhere if they're being given soil with high mulch in it. Do what you can to purchase your products from reputable sources. If you don't have them in your yard and you've been buying you know, mulch and compost and products from a certain nursery or store, keep doing that. Ask the questions to nurseries about jumping worms. They should know about them. Think about other mulch sources. Maybe there's things that we can do with pine needles, hay, native grass mulch, there's some native companies that sell big bluestem mulch. Again, some of these will change your pH probably, but experimenting with this, excuse me, in parts of your garden at first to see what kind of impact that that might have. Grass has much, much different organic matter source and type than leaves do. Leaves break down really quickly, so it's easier for them, earthworms to take that up versus other types of organic matter, and I mentioned this experiment with heat applications, solarization, steam, torch, and at the end I'll be available for questions here as well as outside. We can talk more about that if you're interested. There are places to find more information. The DNR has a website now dedicated to jumping worms. Tons of information on there that we try and keep up-to-date. Our website at the University of Wisconsin-Madison Arboretum. The Great Lakes Worm Watch has a lot of information about earthworms in general, has the recipe for that mustard pour. You can see more information about that on that website, and then of course, I'm available to give talks to groups or just phone calls, that sort of thing. So a lot of information. We're out of time here, and if there's questions, I'm happy to address them. Thank you very much.

audience applauding