Insect Challenges Facing Michigan Woodlots
March 9, 2022More Info
The 2022 MI Ag Ideas to Grow With conference was held virtually, February 28-March 31, 2022. It was a month-long program encompassing many aspects of the agricultural industry and offering a full array of educational sessions for farmers and homeowners interested in food production and other agricultural endeavors. More information can be found at: https://www.canr.msu.edu/miagideas/
- My name's Lindon Kelly. I actually work in irrigation education for Purdue University and Michigan State University and I'm the one here filling the chair. Bruce McKeller originally did the work on putting this program together. I'd like to say thanks to the sponsors, GreenStone Farm Credit. GreenStone's out there helping us with a lotta programming. They've helped us with financially, bring us all of the programs as "Michigan Ag Ideas to Grow With." And if you're interested in other topics, there's a wide range of topics that have been part of this month long venture of "Michigan Ag Ideas to Grow With." The North Central Sustainable Ag and Research Education Program's contributed and Mark Wobbler with the Alaskan Pioneer Fruit Growers Association he's seen fit to help us out financially. And it does bring to our attention that this is just an excellent way to get education out far beyond our borders. So thank you for those assistance in those areas there. Michigan State University is a believer in "And Justice For All" that we're bringing education to all groups within the state, and we do not try to avoid any type of bias one direction or another. You can see our website for the details of the Justice For All, and for the complaints and the types of issues if you have have any. Deb, I think we'll share your screen. - Got me. - I think we got you. We're looking at a picture of, I'm not supposed to say bugs, forest insects and damage. - There you go. That's it. - It's all yours. - Okay, well good morning everybody and thanks for joining us. Hopefully we'll give you some information that will be interesting, if not useful. How's that? The first session this morning, I'm gonna hit gypsy moth really hard because it was a very big deal last summer. If you didn't have gypsy moth caterpillars on your trees last summer, my guess is you might see some this summer. So we'll spend some time with gypsy moth, try to hit a couple other pests with less detail associated. Then take a break like Lindon said, and then this afternoon, or I'm sorry, the second session, the one that starts about 10, figured would focus on oaks, a couple of the insects and really hit oak wilt really hard. So that's what I have in store for you and let's go ahead and get started I think. So, let's see if I can move my sLide. Huh, interesting. Ah, things, there we go. Okay, so gypsy moth, gotta love gypsy moth. It's an interesting insect. It can be a very unpleasant insect if you're living in the area, but it's got all kinds of interesting things about it. We are in the midst of a big gypsy moth outbreak. It started in 2019, especially up in the Northeast and north central part of lower Michigan. 2020, there was 900,000 acres of the defoliation mapped from the air. The DNR and the forest service do that kinda aerial survey, and you can see the big red blobs where there was a lot of defoliation. And then last year, we even exceeded that. About, over a million acres of defoliation that was mapped. Again, a lot of it was in the northern part of lower Michigan, but that is kind of not entirely accurate because the southeast portion of lower Michigan, nobody flies over there because of the big Detroit airport. And then I think southwest Michigan actually had quite a bit more defoliation than what will show up on these maps, partly because it's smaller scattered woodlot areas. Jackson, I know had a lot. It's coming down that way, I think. So lots and lots of gypsy moth. And I thought we might start by talking about some history. I think it's interesting and since you're stuck with me for a while, let's get into it. This is the guy that we have to thank for gypsy moth in North America. You know, we talk about a lot of invasive insects and even some pathogens that were somehow arrived in North America accidentally, maybe they hitchhiked, or they were in wood crating, something like that. Gypsy moth is somewhat unique in that it was intentionally introduced in 1869 by Etienne Leopold Trouvelot and you see his picture there. He was in originally from France and he was living in Medford, Massachusetts at the time. You can see his house there and actually the house is still standing. And what, he was an amateur naturalist. I think he had quite a bit of money perhaps and he did things with insects and trees and plants. And what was happening in the U.S. at the time was that the silk industry was just about to collapse. If you think about silk, it's made by harvesting silk strands from silk worms, big fat caterpillars, and they have silk glands up around their head and you can harvest the silk that they produce. You spin it up and that's how silk is made. And the caterpillars were dying from a disease, a microsporidia disease. Nobody knew that at the time, but they knew they were losing their factories full of caterpillars. And Trouvelot's idea was to go back to France and he had experience with gypsy moth in France. If you look at the little map, that whole green blob that goes from Northern Africa through Europe and east all the way into Asia, that's the native range of gypsy moth. And so he knew about gypsy moth and the caterpillars and so forth and he brought back some gypsy moth eggs and took them to Massachusetts. And he had this idea that he could cross silk moths and gypsy moths and breed some kind of a super silk moth that would be resistant to the disease and still produce a lot of silk. And of course that's not ever gonna work, but I guess his intentions were good. The story goes that some of the caterpillars he was raising escaped out his bedroom window. They became established in the trees behind his house, oak trees, of course, and the rest is kind of history. That's how we ended up with gypsy moth here. And about 10 years after they escaped out his window, the population, you know, as invasive pests due, the population starts to build and to increase. And it becomes really a problem, especially in Massachusetts, including places like Boston. And there was a major attempt to basically eradicate gypsy moth at that time. The picture on the left, that really big oak tree there, you can see the huge ladder going up and all those little blobs in the tree, those are young men. They were hiring young men to go up and scrape egg masses back at the time. Other trees were simply felled and chunked up and burned. And then, you know, 1869, 1870s, 1880s, it's not like they had a lot of insecticides to pick from. What they had was lead arsenic. And so lead arsenic is basically taking lead and grinding it into a powder, mixing it with arsenic and then adding water and making a slurry and they could blow this. They had some high pressure spray equipment and they could drive down the roads and blow lead arsenic all over the trees and the shrubs and the plants. If you can imagine that, there's really nothing that sounds very appealing about that. Plus the people that lived in those areas figured out pretty quickly that when leaves are coated with powdered lead, not to mention the arsenic, the powdered lead kept the leaves from doing any kind of photosynthesis so if you didn't wash that lead off the plants, the trees and the shrubs and so forth would turn yellow and start to die. And so they would come along behind these spray carriages and you can see the old time truck there with the air blast on it, they would wash the lead arsenic off. So now you have streets where people are living and there's literally lead arsenic running down the streets. So that, to me, that's just indicative of how crazy gypsy moth can make people. And I kinda put this in here, this is like, I guess great moments in gypsy moth history or whatever. You can see the eradication effort there. And they were pretty successful. They really knocked the populations down of gypsy moth. So by 1900, there was this expectation that gypsy moth had been managed. It was gonna be nothing but a minor pest. We can cut all the funding that was going into the program there. So that lasts for about two years and then gypsy moth population start building again. It expands, and this is where we get the very first federal quarantine on an invasive pest like that. So kind of a milestone. In 1926, somebody must have said, hey, I got an airplane, let's spray some of that lead arsenic stuff over the trees. And so they tried that. I can't imagine what that would've been like. 1944 as DDT is declassified by the military, they start switching to DDT and spraying DDT from the air. And so through the late '40s and into the almost 1960 a lotta DDT is sprayed in eastern forests for gypsy moth suppression. 1958, they start switching DDT out, they replace it with Sevin, which is another broad spectrum insecticide. It's not as persistent as DDT. 1972, they start testing Bt, the bacteria that we use now. And some of you may have seen the recent press release that the DNR put out literally a couple weeks ago. The governing board of Entomological Society of America has decided that gypsy moth is a problem for people of Romani descent. I guess those were originally the gypsies in Europe and so they want to replace the word gypsy moth with spongy moth, which nobody's very happy about. And I think over time, we'll start having to say spongy moth. But it's gypsy moth now. It's been gypsy moth for 150 years, so I'm gonna keep using it for a while. This shows you the distribution of gypsy moth over time. You can see it starts in Massachusetts. It spreads through New England, gets up into Maine. By 1980, we start finding the first populations in Michigan, up around Midland and Claire. Those populations, there was a lot of spraying that went on in Michigan with Sevin in 1980s, switching over to Bt eventually. By 1995, lower Michigan is all infested. This is from 2017. You can see the red area is the generally infested area: Ontario, Quebec, parts of Eastern Canada up there. It goes, gypsy moth goes into the center part of Wisconsin, down as far as Virginia. And then this is the most recent map that's available. You can see it's still spreading, but much more slowly. We have some different tools. We have Bt, we have pheromones and so forth that we can use to manage gypsy moth now. If you have lived in an area with a gypsy moth outbreak, you're probably very familiar with the caterpillars. They will start feeding usually probably around mid-May, maybe as late as late May, depending on how fast the spring warms up. And they will feed for about six weeks before they spin a cocoon and pupae. And little caterpillars we call 'em first instars, those are the caterpillars that hatch out of egg, okay, and they feed and make little holes in the leaves, and then they have to molt so that they can grow and get bigger and they become a second instar. They feed, they grow, they molt, they become a third instar. And now their heads are bigger, their jaws, their mandibles are a little bit bigger and they're eating more and more of the leaves. They molt again, fourth instars. You can see now the blue dots and the red dots are becoming very apparent. Lots of hairs on these caterpillars. And then the males will have five instars. The females will feed a few more days and have six instars. And you see, what's probably a great big female there, very distinct caterpillars. And of course, if they're feeding up on the leaves, the leaves are going in and the frass, the fecal material is coming out and that is pretty unpleasant if you have a lot of gypsy moths around. And you probably know that moths tend to be more, they're mostly active at night. They start flying around at dusk. They're active through the night. Butterflies in contrast are active during the day. Well moth larvae, okay, in this case, the caterpillars of the gypsy moth, they also prefer to feed at night. And by the time there are third instars, about halfway through that development period, they will feed up in the canopies of trees at night, and then they come down the trees and look for a place to hide out during the day. And then as it starts to get dark, they'll go back up into the trees. And so you get this swarming behavior that will also just make people a little bit crazy. You know, you see 'em on the side of the house there. Some of 'em are gonna try to get in through an open window. That picture there from Newaygo County last summer, a woman sent that to me. I kinda felt like I was having to talk her down off the ledge. She had so much gypsy moth at her property. Everything you see underneath that tree and around this tree, these are all caterpillars. It's just amazing, the density. Gypsy moth is also unique in that it feeds on more than 300 different species of trees and some woody shrubs, but oaks typically drive these outbreaks. They really like oaks, red oaks and white oaks. They will also do a number on aspen, birch, crab apple, basswood, and so forth. We talk about those as being highly preferred species. That means that even the really young caterpillars, those first and second instars, they can feed and survive and develop on these highly preferred trees. Moderately preferred Lindons includes a whole bunch of different species, even some conifers like white spruce and blue spruce and white pines sometimes. And moderately preferred species can be fed upon by oh like third instars. When they're about three weeks old, their jaws are stronger, their gut pH actually changes and they can handle a lot more trees at that point. Very few trees are not good Lindons for gypsy moth. Red maple is one. Ash trees are another. One of the reasons that Ash trees were so abundant in residential areas and urban areas was because everywhere that had gypsy moth was looking for something they could plant the gypsy moths wouldn't feed on. Ash was always a good species until of course, EAB came along. Tulip tree is another one. And if you look at this picture up in the upper right hand corner, you see this was taken at the end of June up by Grayling, and this gives you an idea of what a highly preferred Lindon like red oak, what happens to it versus the red maple that's right next to it. The caterpillars just don't like feeding on that. Now with hardwood trees, they can literally lose 100% of their foliage. And what will happen is it triggers the trees to produce a second set of buds, and we call it reflushing. So somewhere between mid and late July, there will be a second set of leaves that are out, and they're gonna do photosynthesis and make carbohydrates for the tree and the tree is typically gonna be fine. It, you know, in a way it's tapping into their stored energy, but if the tree is reasonably healthy, they can re-flush at least three years, four years, sometimes longer. And by the time they're really severely stressed, typically those gypsy moth outbreaks are running their course and starting to collapse. Now with conifer trees, pines, fur, spruce, hemlock, and so forth, their physiology is different. They cannot reflush. So when they lose all the needles, they die. And if you look at the tree on the left over here, this is a spruce. These branches that have lost their foliage, those branches will die. It looks like most of the tree will stay alive, but you're gonna have some big areas of dead branches. This tree over here, there was a row of spruce and little white pines growing under some big oak trees. The caterpillars that fell off of the oak trees just started feeding on the pines and spruces, and you can see those trees, they are dead. If you don't kill the caterpillars before the severe defoliation happens, you're gonna lose the trees. Once the caterpillars finish their feeding, they're gonna spin a cocoon, and they will pupate inside that cocoon. That takes usually about eight or 10 days. The moths come out. The moths are not a problem, okay. They're not gonna feed. They don't do anything. They're gonna mate and the females will lay their eggs and that will be the end of their lifespan. The females, if you look at 'em, they have these nice, pretty white wings, and it looks like they should be able to fly, but they have no flight muscles inside their body. She is just chalk full of eggs, okay. The males are pretty good flyers. They kind of fly back and forth. They do a little zig-zaggy kind of pattern because they are tracked, they are tracking a sex pheromone produced by the female moths. And it's a very potent sex pheromone. The moths, you see the males have those really crazy antenna. We call 'em bipectinate antennae. There's just a lot of surface area on there, and they can track even a couple molecules of that sex pheromone to find the females. Now, one of the things to call your attention to is that last summer there was people buying pheromone traps with the idea that they could capture lots of moths and reduce defoliation, and maybe not have as many gypsy moths next year. And I am here to tell you that that is a complete and utter waste of your money. There's lots and lots of moths. That milk carton trap there in the middle, you can capture 250 males in there, but there's a good chance most of those males have already mated. And it doesn't matter anyway, because one male can meet with multiple females. And it's the females that lay the eggs and determine how many gypsy moths will be around next year. So don't make that mistake, okay. Now, once the females have come out of the cocoon, they lay a egg mass, just one egg mass. The female covers it up with hairs. You may have seen these. Sometimes the density of egg masses can just be incredibly high. Usually they're on trees up and on the underside of big branches, but they can be on dog houses or in firewood or even on vehicles and things. And the egg masses can be helpful, especially when we're at this point in an outbreak cycle, because if the egg masses are all mostly relatively small, that's a good sign that the outbreak is getting ready to collapse. That means that the females were not real healthy. Small egg mass will have about 200 or 250 eggs in it. A big healthy, robust female will lay a big three inch long egg mass with lots of layers of eggs, and that can have 1,000 or more eggs in it. So if you're in an area and you're looking at egg masses, kind of get a sense for the size of them. Couple things I also wanted to mention, there are natural enemies that attack gypsy moth, okay. They can't keep up during outbreaks, but they help out. This is one that's really good. We like this one. It specializes on gypsy moth eggs. It is a tiny wasp, it's a parasitoid. So this tiny little wasp will lay her egg into an egg in gypsy moth egg mass. The little wasp larva will develop inside the egg and then come out as an adult, which kills the gypsy moth egg. And so this little parasitoid has two generations a year. One is gonna happen about the end of July, and then another one that comes about four weeks later. You can sometimes see 'em hopping around on a gypsy moth egg mass if you look closely. But this is something good. We like 'em. We tell people to leave the egg masses out there until at least mid or late September so that these little wasps can do their thing. And I point that out because if you go into, if you get online and go to biocontrol supply houses, garden stores, those kinds of things, you can buy an egg parasitoid called Trichogramma, okay, that's the genus. And they will send you a card like you see down below, and that is a card with pupae of grain moths. And the pupae, or excuse me, eggs of gray moths, and the eggs are full of Trichogramma. And the idea is you take that little egg card, you can staple it to a tree. The adult Trichogramma will come out and go attack eggs of lepidopteran insects, moths and butterflies. And they are not very discriminatory. They will attack pretty much any kind of moth or butterfly egg, except that they do not attack gypsy moth eggs, okay. Gypsy moth, and a few related insects, white mark tussock moth, for example, they cannot be parasitized by Trichogramma. That does not stop these places from selling you Trichogramma for gypsy moth biocontrol. Don't buy it. It's not good. You're you're just putting something out there that's gonna probably attack eggs of native butterflies and moths. What will actually cause the outbreaks to collapse are two diseases. One is a viruses that we call NPV, that's nuclear polyhedrosis virus which is why we call it NPV. And there is a fungus called Entomophaga maimaiga, entomo meaning insect and phaga means feeding, so it's a fungus that attacks insects. The NPV disease, we count on it. It's always present in gypsy moth population and it can kill insects or some of the insects will become infected and have a sublethal load of virus. And that tends to make them smaller. Those females produce less eggs and so forth. When a gypsy moth outbreak occurs and you have these high densities of caterpillars, they get stressed. They don't have enough to eat. They're competing with each other for foliage to feed on and places to rest. They interact, they come into contact with each other and eventually this virus will build up and typically it's what causes the population to collapse. You will see cadavers on trees by late June, 4th of July, mid-July. And if they are hanging in an upside down V and they liquefy, okay, that's what the virus does, and you touch 'em and they smell really bad, that's a good sign that the virus is knocking out the population. The fungus is also present. You can have both of these in the same area. You can have dead cadavers on the same tree in fact. The fungus depends on the spring weather. It has to be the right amount of rain, not too cold, not too warm. And if the fungus gets going and germinates, it can also cause a high density outbreak population to collapse. And you can see an epizootic on that tree there. That's a tree that was down in Allegan and lots and lots of dead caterpillars. They do not liquefy. They dry out. They almost are like, they don't, they're not crisp, but they're kinda like a stale potato chip. And that will also help drive the outbreak down if the weather is conducive. What do you do in an urban area if you have trees, you know, in your yard, near the house or whatever, and you have gypsy moth? You can take advantage of that swarming behavior and you give the insects a place to hide during the day. You tie a burlap band around the trunk of the tree, the insects will crawl in there during the day, and then it's up to you to come knock those caterpillars into soapy water, suck 'em up with a Shop Vac, do whatever you have to do and you do it every day, and it's gonna be about three weeks where you have to do this, but that can help. You can keep a lot of caterpillars off your tree. Scraping egg masses, anytime from fall through spring, you just soak 'em in some soapy water, toss 'em in a campfire, whatever you, whatever floats your boat, that's gonna kill hundreds, maybe 1,000 caterpillars per egg mass. You can also spray those egg masses with horticultural oil, something like, I think it's called Golden Sun Spray Oil, which is basically just soybean oil. Or you can mix soybean oil and liquid dish soap, something like Dawn dish soap will do the same thing. Dish soap by itself is probably not gonna a good enough job. You gotta have that oil in there. You're basically suffocating the eggs. You can use a lot of insecticides. Just about any insecticide will kill gypsy moth caterpillars. The problem is you gotta get it up into the tree where the insects are gonna be feeding. And when you have big tall trees, you get a lot of drift. You're gonna have impacts on beneficial insects, non-targets, natural enemies, and so forth. The systemic products that we use for things like emerald ash borer, imidacloprid, dinotefuran, for example, they just don't work very well with caterpillars. You can try it, but it's, I can tell you it's not gonna work very well. Emamectin benzoate is the insecticide that we use for bronze birch borer, emerald ash borer and so forth and that is only going to be effective for one year with gypsy moth. I just heard that last month from one of the distributors that sells the emamectin benzoate, you get three years of emerald ash borer control, but you only get one year of gypsy moth control. And I just think that's way too expensive to be doing for gypsy moth. You can buy Ace-Caps, okay, and you drill into the tree and you shove a capsule into the tree. That can work, okay. That's like a orthene based insecticide. That can be pretty effective. Bt is definitely your best option though. Bt is a bacteria that's occurs naturally in the soil. You buy these products. All they've done is ferment a bunch of the bacteria and it's approved for organic gardens and organic farms and so forth. What you wanna do is put the Bt on the leaves on the trees when the caterpillars are still really young, okay. So the first and second instars that's gonna be right around Memorial Day is when you wanna be spraying that, and it's pretty cheap too, as insecticides go. It's one of the cheapest. It's not harmful to humans or pets or birds or mammals or even beneficial insects. That's what we will see being sprayed by airplanes in a number of areas this year. Townships, lake associations, and so forth have hired aerial applicators to spray Bt. It's, you know, you're not spraying a nerve poison. You don't get 100% control of all the caterpillars out there, but you get good control. I put that picture in there from Grayling. You can see all those trees that have absolutely no leaves on 'em, that's where gypsy moth was feeding. Those are pin oaks. And if you look at that square, notice how there's really sharp edges on that green square? Well, that's part of the area that was sprayed with Bt. That's up at the national guard training grounds, and they needed some forest area for the soldiers to do their practicing or whatever, so you can see that that Bt can be very effective. What we try to avoid is spraying Bt over just woodlots and forests. Yeah, I know there's a lot of caterpillars in there, but you know what that's where the pathogens are gonna build up. Those trees, if they die from gypsy moth defoliation, it's gonna be because they were very stressed and had some other problems. And so you just kinda wait out, give it maybe three years and the outbreak should collapse. So lots of information is online. You can look at, you just Google MSU IPM gypsy moth, and you can get all sorts of one or two page little summaries of information that might be useful. So if it's okay, I'm gonna keep-- - [Lindon] Couple question, couple questions, Dr. McCullough. - Sure. - First off for the group, please use the Q and A, and I'll try to, if she has a gap, in her presentation, I'll try to get her to answer the questions. First on Bt, are there different strains? Is there a strain specific for this? - There are different strains of Bt, but what you want is Btk, okay. Btk is Bacillus thuringiensis kurstaki, and that is toxic to caterpillars. There is a Bti that you use sometimes for things like black flies, little charcoal looking briquette types of things that you can float in water. There's a Btt that's for a specific type of beetle, tenebrionid beetles. Those are not really very common. So if you go to Home Depot or Lowe's, or some other type of garden store, and you look at Bt, what you want is the Btk, and that's probably about all they're gonna be selling. So it shouldn't be too tough to find. - Okay, great. I think that also covered Ron's question also. And then back when we were talking about parasitic wasps you told us about that the one that we commonly buy at the hardware store, isn't the right one. Where do you get the correct one, for Eric here. - You, you're not gonna be able to buy. The Ooencyrtus kuvanae is the one that was released. It was imported. I believe it's native to Japan and it was released in the 1920s. And it's here, it's all over Michigan, so it will be doing its thing on gypsy moth egg masses. The problem with it is it's so tiny, it can only parasitize the top layer of the gypsy moth egg masses. So if you have a big fat egg mass, it'll kill about five or 10% of the eggs. If you have a small egg mass, it might kill 30 or 35%. That's about as good as it's gonna get. And it's not something that you can purchase or, you know, try to increase the number of wasps in your area. You just kinda have to let nature run its course with this. And, you know, the one you just don't wanna waste your money on is Trichogramma. There are very loose regulations about bio control agents like that, and Michigan is one of the states that has some of the loosest regulations. So just save your money and maybe buy some Bt or whatever. - [Lindon] Okay, thank you, And to the group out there, please put your questions in and we'll try to try to get them to Dr. McCullough. What's next Dr. McCullough? - Okay, so let's, let's talk about a little insect. I don't know how many of you have hemlock trees in your woodlots, but I know there is a lot of hemlock down in Southwest Michigan, especially as you start getting closer to Lake Michigan and the shoreline over there, some of those sandy areas and the dunes and so forth. And I wanna make sure that everybody is aware of hemlock woolly adelgid. Gypsy moth really doesn't kill very many trees. You know, they get defoliated, there's nasty caterpillars and frass for a while, but the trees are gonna recover. We've had gypsy moth outbreaks before, and we'll have 'em again. Hemlock woolly adelgid is a different kettle of fish, shall we say. It is a tree killer. And it's really sad because I think a lot of us love hemlock trees. They're big, they can be very long lived. They can be over 300 years old. They're very important for wildlife because they have these dense canopies and provide a lot of winter cover. They have big influences on things like soil and water pH. They often grow along streams and rivers and so forth, and just really important in terms of dunes and stabilizing the dunes that we have in Western Lower Michigan. And this little insect, this tiny little insect, again it's native to Japan, accidentally introduced. Don't know how it got here. In the Eastern U.S. it was first found in Virginia in 1951. And it is a sap feeding insect. And you can see, I don't know if you can see my cursor or not, but this is an insect, this isn't adelgid with all the wax pulled away and they feed by sucking the nutrients and the good stuff from the cells that line the vascular tissue in woody twigs. So the vascular tissue is where the water and the nutrients are moving from the branches out into the small shoots and into the needles eventually. And these insects, this is a little adelgid here. This is her head end. She has pierced the base of the needle, and this is her stylet and it's going down into the chute where she can access these really good nutritious kinds of cells. And as they feed, there are pores in the body of these insects and they secrete this white waxy stuff. It's like little filaments of wax, and that's why you see something that looks like this in the lower right hand corner. You get these little balls of wool down there and that's hemlock woolly adelgid. They don't fly. It's interesting that they move around so well, but they don't fly. The only way that they can disperse is the very first instar, okay, the new little tiny insects that hatch out of the eggs, we call 'em crawlers, because they have these tiny little legs and they can move about on the tree and they can be blown in the wind. And if they land on another hemlock, they'll start feeding. We also are real sure that birds and probably some other mammals can move the crawlers around, possibly even the eggs, you know, accidentally move 'em from tree to tree. Let's see there's two generations per year, okay, and so you have two different opportunities, one typically around May and another one towards mid-June, where these crawlers are out and about and can be moved around. The feeding by the adelgids, not only are they pulling nutrients out of the tree, but they cause a reaction in the tree, almost like the immune system goes haywire. And it causes, it disrupts the ability of the trees to move water. And so what you'll see is the needles start to die and fall off. You'll get buds dying. You can see the pictures down below. Those are trees that were in Norton Shores actually. The canopies become very thin, a lot of dead tips and so forth. And eventually anywhere from three or four years after infestation up to maybe 10 or 12 years after infestation, most of these trees are gonna die. And this is what we're trying to avoid. These are trees in the east, Great Smokey Mountain National Park, this is down in North Carolina. New England, that picture was taken in Connecticut. All those dead trees are hemlock trees that were killed by hemlock woolly adelgid. This is where we know we have hemlock woolly adelgid currently. A lot of effort going into surveys. You're gonna hear about SISMAs in a little while, and a lot of SIMSA people, the DNR people, Department of Ag people, the Nature Conservancy is helping to look for hemlock woolly adelgid. And all these little red spots that you see are areas that have an infestation. And there's something that we, it's pretty obvious, these infestations are running right along the Lake Michigan shore there. And we're not entirely sure why that is. We have some hypotheses. These tend to be really nice homes, often summer homes, often very wealthy people. And there's something that wealthy people like, and that is they have young hemlock trees imported often, not from Michigan, from places like West Virginia, North Carolina, maybe even Pennsylvania and they plant these young trees underneath tall native hemlock trees to fill in, they call it. And anytime you're moving nursery trees around, you're running the risk of bringing hemlock woolly adelgid with you. And we know for sure that one of the first infestations that got started down here in Ottawa County was attributed to nursery stock that was planted beneath some large native hemlocks and nobody knew to look at the white things on the trees and that may have gotten a whole lot of this little area down here infested. We also know that hemlock is not distributed the same across the state. Most of it's in the UP, northern lower Michigan, but there is a band that runs through here along the lake shore, where we have these infestations. But we also think that weather has a lot to do with it. And if you've lived in Michigan for any amount of time, you know, about lake effect weather and the influence of Lake Michigan that actually serves to keep winter temperatures warmer, and the snow helps to insulate the insects and that's really important for hemlock woolly adelgid because they feed through the winter. That's not very common. Most insects go dormant and they kind of curl up either as eggs or pupae maybe, and wait out the winter. Well, hemlock woolly adelgids keep feeding. And this, we know that they can be killed if it gets cold enough. These are data that we got at two sites. One is down at Holland in Ottawa county. One is at Norton Shores, both along the lake shore and we had weather stations out there. And these green lines are the minimum temperature that was reported at these two different sites. And you can see, we actually had a lot of hemlock adelgid mortality in the winter of 2018 to 2019. And it occurred because we had these, this cold night on the 30th of January. And that caused a lot of the adelgids to die. In fact, here where we got down to minus 12 degrees Fahrenheit, almost all the adelgids were killed, more than 90% mortality on all the trees that we were sampling. So we know cold temperatures can knock a population down. You're not gonna eradicate it, 'cause some of those adelgids are in nice little hidey places and they'll survive. But if it gets cold enough, we can see a lot of mortality. If you're by the lake though, it's rarely gonna get that cold. So the following winter, 2019 to 2020, it never got below zero. We didn't see any detectable hemlock adelgid mortality. The sistens, this is the generation that feeds during the winter. The next winter, 2020 to 2021, we did have some cold temperatures. There was a night in February where it got down to minus 14. There was a two week period where it just stayed cold in February and we did see some mortality somewhere, you know, depending on which tree we sampled and so forth, anywhere from 50 to 70% of the adelgids were dead. About 60% were killed during the winter. Not quite the level of mortality that we would've liked. I can tell you, we monitored this over the most recent winter and I know there was some cold days. We don't have the weather stations out there anymore, but we haven't seen any hemlock adelgid mortality to get excited about, so unfortunately. If you think about winter temperatures and the fact that the adelgids should have spread to the east and not just be found right along the lake shore, we know that the lake effect weather is having an impact on where they can survive over time. And one of the things that we are looking at is the influence of climate change on winter temperatures. And we're doing it in relation to hemlock adelgids, but I think it has a lot of implications for other insects, you know, agricultural pests, everything from road crews and snow plowing to winter recreation and so forth. And this is some research that Jeff Andreson, if you know Jeff, he's the state climatologist and a professor here at MSU, another fellow that works with him, Mike Keifer did. And what we did was to get PRISM weather data. That's a great big old database full of weather data over a 37 year period. And then we took the six major climate change models that you can see listed here. If you're into climate change, some of these will be familiar. Two of 'em are Japanese models, one's from Australia, one's from Canada, one is from the UK and there is something called a regional climate model, and that was developed by people mostly outta Wisconsin along with Jeff Andreson. And that takes these global climate models and incorporates the impact of the Great Lakes on the temperatures that are gonna be experienced or projected to be experienced, okay. So we're including the impact of Lake Michigan, Lake Superior and so forth. And we ran this, we wanted to see what temperatures would look like in the future. And so we chose a climate change model here, it was this one in particular. It's a business as usual. It's assuming that we don't do anything significant to reduce carbon emissions, okay, which seems like a pretty good bet the way things are going. So I just wanted to show you this 'cause I think it's interesting. It has a lot of implications for us. This is mid-century. This is in 20 years, okay, and this is the base model. So between 1981 and 1999, if you looked at extreme minimum winter temperatures, okay, and averaged it out, what you can see is the western UP is cold. They get somewhere between 20 and 30 days per year, whoops, go back. 20 to 30 days per year that are gonna be below minus four degrees Fahrenheit, which is minus 20 degrees centigrade. Dang it. If you look at lower Michigan, the green areas, that's where you have seven to 14 days of really cold temperatures, okay, minus four degrees. The orange and yellowish kinds of colors, that's three to four days of cold temperatures. You can see that even in this baseline period, there is a band of purple, light purple here, where we have two to three days of cold temperatures. That's lake effect weather. And then if you run these, climate change models with the regional impact adjusted for the regional impact of Lake Michigan, let's say, and Lake Superior and Lake Huron, what you should notice is that southern lower Michigan becomes purple, okay, by and large purple. So now we're down to two or three days of really cold temperatures during a winter on average. It gets warmer up here, maybe five or six days, as opposed to seven to 14 days of cold temperatures. Depending on which model you look at, even the UP starts to get a little bit warmer. And we can do this for the end of the century. You know, that's a long ways off, so your confidence in these projections is not as high, but lower Michigan starts to become a banana belt, okay, where we're just not seeing these cold temperatures at all by the end of the century. And what that means in terms of hemlock adelgid, is that most of the state with the possible exception of Western UP is gonna be suitable for hemlock adelgid, and we won't see these big winter die offs that we get every once in a while with a cold winter. So as far as hemlock adelgid goes, if you have hemlocks in your area, you can protect them from hemlock adelgid and you do it with either imidacloprid or dinotefuran, systemic insecticides. The Eastern people have been using these, not just for landscape trees, but in the forest, protecting watersheds, protecting an endangered species of hemlock that occurs in the Carolinas. Just a lot of use of this over time. With imidacloprid in particular, one application will give you at least four years and probably closer to five or six years of hemlock woolly adelgid control. Dinotefuran gives you about two years of control. It doesn't persist as long, but it gets into the tree and it kills the insects more rapidly than imidacloprid. What the state is doing right now with funding from the U.S. Forest Service and other institutions is to detect infestations and then to treat the invested trees primarily with imidacloprid and it's almost all being delivered by trunk injection. And what that means is that the insecticide is put directly into the tree, it stays within the tree. You don't have any worries about it getting into the soil or even worse into the water. Occasionally dinotefuran is applied to the lower part of the trunk, especially on really small trees. Those are difficult to trunk inject. But by and large, almost all of the trees are being treated with imidacloprid. Trees that are near infested trees are also being treated because if the tree is tall, you could have adelgids up in the top of the tree that you just can't see. And the program is starting at the northernmost infestations, trying to protect the bulk of the hemlock resource in Michigan, northern, lower, and upper Michigan. And then as funding and time and labor permit, they work their way south. So I gotta tell you those infestations in Allegan county, Ottawa county, either the landowners are gonna have to treat their own trees, or they're not gonna be treated and they're gonna end up dying because there just isn't enough funding to move further south like that. I thought I'd throw this in just to make sure that everybody's aware that not every insect on hemlock adelgid is, not every insect on hemlock is hemlock woolly adelgid. So there is another invasive insect that is a scale. Okay, you see those insect, those needles that look really dirty? They have like brown little things on 'em. Those are scale insects. They are also feeding on sap, but they are only on the needles. You don't see 'em on at the base of the needles feeding on the shoots, okay. And they're kind of a brown color, sometimes kind of a yellowish color, sometimes dirty white. Not that big of a deal. You can have elongate hemlock scale for years and years and not really affect the tree too much, other than it looks kind of cruddy. And we can control both of those pests with dinotefuran, whereas imidacloprid is only gonna work on the adelgids. I thought I'd give you a little bit of a quiz. So if you see hemlocks and you see these little white doobers on there, it's not necessarily hemlock woolly adelgid, if they're not feeding at the base of the needles. This is oak skeletonizer, a tiny little moth, and it pupates in these little cocoons that are about the size of a skinny grain of rice. Okay, this is one that you may have seen. This is pine bark adelgid, very close relation to hemlock woolly adelgid, but it will only be on white pine. Only on the bark, okay. You can see trees get really infested like this. This is not good for the tree. A little bit of pine bark adelgid is not a problem typically. Maybe you know what this is. And sometimes people get excited about this. These are spittle bugs, okay. Not gonna be a problem for the hemlock trees. This one, take a look at that. What do you see? That's one you'd wanna worry about. That's hemlocks, elongate, hemlock scale on the needles, but hemlock woolly adelgid down on the shoots, right at the base of the needles. So if you live or have property or have hemlock trees outside of Allegan, Ottawa, Muskegon, Mason, or Oceana counties, and you see hemlock adelgids let us know, because that would be, we really don't want any more of this insect in the state than what we have right now. Okay, so Lindon is there anything we need to... - [Lindon] I don't see any, I don't see any questions. please type your questions into the chat. We're gonna take what a 10 minute break? Come back at 10:05. Is that okay with you, Deb? - You know what Lindon can we take about three or four more minutes and bust through one more little chunk? - [Lindon] Sure, sure. - If everybody's okay with that, I promise I'll go through this quickly. I wanted to tell you a little bit about beech scale and beech bark disease, because I think again, if you're over on the west side of southwest lower Michigan, you probably have some beech trees. I know there's some beautiful areas, Warren Woods, and the state park down there in Berrien County and so forth, that have some big, beautiful beech trees. And we have beech bark disease in the state. We've known about it since 2000. The first area we found was up at Ludington State Park. And a few weeks later, we found it in the UP north of Newbury in Moose county, Bassilate Campground. It's another one that leads to trees dying. And beech bark disease, we talk about it like it's one thing, but it's actually a complex. It involves an invasive insect, this tiny little beech scale and an invasive fungal pathogen, neonectaria, and the really bad species is fagisuga. It's much more virulent than some of the native neonectria fungi that we have here. The scale insects are really small. They're tiny. They're like hemlock woolly adelgid in that they're parthenogenetic. They are all females. No males at all, ever. They simply reproduce, basically making little clones of themselves. The sisters are all genetically identical to each other and to the mother. You get some genetic variability in there via mutation, but there is no genetic recombination because there's no mating. And these tiny little insects, I think you can see over here on the left, this is a penny. And if you look at that little circle and you magnify it, you can see some little insects in there. And if you magnify it even more, these are the beech scale insects. Again, when they hatch out of the eggs, that first instar, those are crawlers. See how they have little, tiny legs, whoops, and little tiny eyes and they move about, okay. And again, they can be blown in the wind and probably carried by birds to new areas and so forth. And these insects are also sap feeders. So they poke their little mouth parts into the bark on beech trees and they suck sap out of the inner bark, the phloem, where all the nutrients are being transported from the leaves down to the roots. And again, I just thought, I'd emphasize how small these are. This is three adult scale insects on a penny. You see just one right there. We know they can blow in the wind. I have seen a new infestation get started because some infested beech logs were taken to a sawmill. We probably are moving 'em by birds. This is somebody that brushed up against the beech tree, got a whole bunch of beech scale on her jacket and if she was to touch another beech tree, she would probably transfer the scale insects. They also produce wax, very much like hemlock woolly adelgid, except they're just a lot smaller, okay, and that gives the trees this white look, when they get really heavily infested. The scale insects, the crawlers have to latch onto the bark. And so if the bark is rough or you have old branch stubs, that's where the scales are going to latch on first. And what that means is you tend to get really big, old, cool trees getting infested first, and those beech scales are what will lead to beech bark disease. And I thought I'd throw this in because beech blight aphid is not beech scale. Okay, very different situation. Beech blight aphid is actually pretty common, especially in the southern half of lower Michigan and especially in southwest Michigan. These are cute little insects. They are sap feeders. You will find them on the chutes, you know, not the real thick branches, but the young branches that still have some kinda green bark on there. And they suck sap and they spew out, they excrete just a whole bunch of honeydew. So the ground will get sticky with the honeydew and then the black sooty mold will grow on the honeydew and the insects themselves, they're very mobile. Beech scales don't move. Once they poke their mouth parts into the bark, they will never move again. But beech blight aphids, they put their little hinds ends up in the air and they literally dance. If you go to YouTube you can see people just love taking videos of these and then posting 'em online. So we're not talking about beech blight aphid, they're no big deal, but the beech scales are. Because every time a beech scale pokes its mouth parts in, feeds, makes eggs, and then dies, it leaves a tiny little wound in the bark. And that lets fungus, fungi invade the tree and get through that bark into the beech tree. And the bad fungus, the invasive fungus will kill patches of the inner bark, the phloem, okay, the part that carries the nutrients, you can see how discolored this is. And what happens is those patches of dead tissue start to coalesce and that can kill branches and eventually the entire tree. You don't see anything necessarily on the outside of the tree. You see this cracking here. That's because the inner bark is dead and if you were to chip this bark away, you would see that it's all brown like this. And it's really sad. The fungus kind of girdles the tree, okay. It girdle's big branches. Once it's into the trunk, it will girdle the trunk. These are pictures from Tahquamenon Falls, I think this is upper falls. They've removed hundreds of beech trees that were along the trails and in the campgrounds because they have beech bark disease. And once beech trees get infected by beech bark disease, they become weak and prone to snapping and falling and so forth. This is a picture from New England. I think this is actually New Hampshire. These are trees that have become infected with the fungus, but have not died, and they're trying to wall off and compartmentalize the fungus. And they're just, they're not dead, but they're not really living very well. So we have terms. The advancing front refers to any area where the beech scale insect is established. The killing front comes behind and that's where the fungus is present and is starting to infect some trees. You have some healthy trees. You have a lotta trees that are declining because the fungus is in there maybe dying, probably some dead trees. The aftermath forest is what we call the area after the first wave of beech bark disease goes through. You might have some of those culled trees. You'll have a lot of dead trees, and one of the things that happens with beech is you get these really dense thickets of sprouts coming up. Roots sprouts, sometimes stump sprouts, but mostly roots sprouts and deer do not like feeding on beech. And so this just becomes kind of a really bad thing where you end up with lots and lots of these young beech sprouts. They're too dense, you can't hardly walk through 'em. The deer don't like, 'em, they just really don't serve much purpose at all. What has happened in the east, northeast in particular is that the first wave of beech bark disease kills about half of the big trees, the trees that are bigger than 10 inches in diameter. Another 25% get infected, but don't necessarily die. You can see what we're looking at losing in Michigan. And that's, nobody's gonna be worried about losing beech trees because of their timber value, it's their wildlife value. Beech nuts are really important, especially in areas where you don't have oak trees. Those beech nuts are, you get a lot of 'em every two years and every little animal and big animal in the forest wants to feed on beech nuts. This just shows what we know about it. You can see the two areas where things got started back in 2000. You can see this is the advancing front, the red spots as of 2015, kind of moving its way through lower Michigan. We don't know where the advancing front is right now. We haven't been able to survey it in a while. As of 2012 and 2013, we were looking at the impacts of beech bark disease. You can see, we have these 62 long term plots. Some of them go down, I think Saugatuck area is the most southern one, southernly plot that we had. And we went back and revisited these sites, looked at the beech trees and the beech condition in 2012 and 2013. And let me show you this. This is in 2002 when we first set up those 62 plots. We had 34 in upper Michigan, 28 and lower Michigan, 14 of the 34 had beech scale at the time. Almost none of the beech were dead though. And in lower Michigan, nine of the 28 sites had beech scale, almost nothing dead. And the ones that were dead, it was like wind breaks and so forth. And then we go back in 2012, okay, now 33 of these 34 sites have beech scale. Overall 25% of the trees were dead. If you look at these 14 areas, 50% of the beech trees in those sites were dead. In lower Michigan though, things went more slowly. 22 of the sites had beech scale in 2013, but almost none of it was dead. And I think that is changing. If you're up around Sleeping Bear, the lake shore up there anywhere Bensey County, that area, starting to see a lot of mortality and I think the bad fungus has moved into lower Michigan. And what we're gonna do, we just started this summer is to go back, it'll be 20 years now and revisit all those sites and see what's dead and what's alive. And Nick is a grad student. He started that this summer and kinda worked in the sites that are closest to campus. We wanna put in a couple new sites to look at the advancing front. Looking down here at Berrien County, probably, and then over here, we know they found beech scale for the first time in Bay County last summer. We're looking up here in the, kind of in the Huron National Forest as well. And possibly we run out of beech somewhere in the central UP, but we're gonna try to look at Menominee County or a little bit further west. And then one more thing, if you hang with me, I promise this one's really short. If you have black walnut, you may be familiar with a thousand cankers disease. It's a disease of black walnut that is vectored by the Walnut twig beetle, which is a tiny little insect native to the Southwest part of the U.S. mostly Southern California and down into Mexico. And this beetle can vector this fungus. The beetles get into the branches typically. They bring the fungus with them and then the fungus causes little patches of tissue to die, okay. And in the west, it is a big deal. It is killed awful lot of black walnut trees that are in landscapes or wind breaks, or they actually have a number of orchards where they harvest the walnuts from the black walnut trees. It was not known to be in the east until 2010 when it was found in Tennessee. But Colorado, Utah, all of those Rocky Mountain states and now as far as Idaho and Oregon, lots and lots of dead walnuts there. The beetle was has been found in a number of eastern states, including Indiana and Ohio. We've trapped one in southern Michigan. And there's a lot of concern about this, 'cause you get all these little tiny dead spots, these little tiny cankers, and they coalesce as you can see here and now you've got girdled branches and eventually what's happened in the west is that the trees are dying. This is some pictures, I think these are all from Colorado here. You can see just the declining dying trees. But guess what, this insect in the east is just not having much of an impact at all. It's been watched, it's been monitored. People are working on it. But in fact, if you look at the eastern U.S., black walnut is native here. It's well adapted to the soils and the climate here. And this is the first time I can remember talking about a insect that we were really concerned about early on, and we simply, let's just say, we're cautiously optimistic. We are taking this off the list of bad invasive pests and it looks like black Walnut is doing just fine. - [Lindon] So Dr. McCullough, there was a question early on about whether there was feeding on the second wave of leaves that come out back when we were talking about gypsy moth? - Right, yeah, a good question. And the answer is no. The gypsy moths will finish and spin their cocoons and pupate, right almost always by the 4th of July, right around the first part of July, maybe the second week of July. And the trees that have been severely defoliated, won't be able to put those new leaves out for at least a couple weeks. It takes 'em a little bit of time. And so when those new leaves are out there won't be any gypsy moth caterpillars around. Very rarely, I mean literally once or twice, I have seen other insects that feed late in the summer, things like orange striped oak worm come back and attack, not attack, but feed on leaves of trees that have refoliated after gypsy moth defoliation. And that can be a problem for the trees, kind of a double whammy in the same summer, but that is very rare. Most of the time that second set of leaves does just fine. - [Lindon] Okay. So I think we said we were gonna take a break till 10:15. The only question that we could answer after 10:15 would be, how do I get one of those handy dandy, little injectors?