Archive for the ‘Invasive Pests’ Category

Invasive Alert: Chinese Tallow Tree

tallowtree-fruitjpg-705a703f8770e9b6

The state of Alabama doesn’t worry too much about invasive plants like privet or kudzu, which have seemed to take over much of the south. No, the one botanists fear is the Chinese tallow tree.

Also known as the popcorn tree for the white, waxy tallow substance on its fruit that kind of looks like popcorn, this tree is so invasive in Alabama that they have taken to fighting it from the air.

So why should Michigan be concerned?

The U.S. Forest Service has data that shows the tree’s population has grown 500% between 1991 and 2005.

The tree thrives in wetland environments, but is not limited to them. The tree can grow in suburban areas, forest edges, and even sand dunes. It is still a popular ornamental tree in residential neighborhoods for its bright red fall color.

Yet once established this tree spreads quick. One mature Chinese tallow can produce 100,000 seeds every year. Those seeds are spread by birds and other animals, as well as flood waters. And the seeds can stay dormant for years before sprouting.

In addition to seeds, Chinese tallow has an extensive root system, with new shoots sprouting along it. These two things combined mean tallow can grow in clusters so thick that it drowns out all other native plants.

And it’s not that far away. According to a map from the University of Georgia’s Center for Invasive Species and Ecosystem Health, the plant was found in a county in southern Wisconsin as of July 2017.

The moral of this story?

Keep an eye out for plants that look unusual to you. It may be something that doesn’t belong. Learn from Alabama’s experience. If you find something you’re not sure of, check out the Midwest Invasive Species Information Network and report it if it’s invasive.

Be wary of what you purchase at a nursery or your local home supply store garden center. Make sure that it’s native to Michigan and you aren’t becoming the source of a new infestation of an invasive plant.

Read more about Chinese tallow tree below.

 

Alabama fears this invasive plant so much we attacked it from the air

Posted July 31, 2017, News from Al.com

Dennis Pillion | dpillion@al.com

When talking about invasive plants in Alabama, kudzu and privet tend to be the ones people are most familiar with, but they’re not the ones Alabama botanists and wildlife officials are most worried about.

One of those is the Chinese tallow tree, or popcorn tree, one of Alabama’s most invasive species.

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Watch Out for Wild Parsnip

Invasive plants and animals are typically only a threat to other plants and animals, but occasionally they can be a danger to us as well.

While giant hogweed is on the watch list in Michigan as a new invasive species, wild parsnip is becoming more common, especially in the northern parts of Michigan and the Upper Peninsula.

And while it’s looks similar to other members of the wild carrot family, this is one plant you definitely don’t want to mess with. Contact with its juices can cause rashes, blisters, and burns. The skin discoloration can last for years.

The article below has more details about wild parsnip. You can also get good identification information here.

Watch Out for Wild Parsnip

Originally published: July 19, 2016

U.S. Forest Service, Hiawatha National Forest

Flowering Yellow umbel of Wild ParsnipGladstone, MI — Wild Parsnip, also known as Pastinaca sativa, is an herbaceous perennial with yellow-flowered umbels atop 3- to 5-foot tall stems.  While it may be pretty to look at, people who touch the plant soon discover its less appealing trait:  When the juices of the Wild Parsnip plant touch your skin and are exposed to ultra-violet light, they cause serious rashes, burns and blisters called “phytophotodermatitis.” The resulting skin discoloration can last several months. If you come in contact with Wild Parsnip and notice development of burns, cover the affected area with a cool, wet cloth and seek medical attention.

Wild Parsnip’s toxic compounds (called furanocoumarins) are found in the juices of its leaves, stems, flowers, and even fruits. Phytophotodermatitis will usually appear within 24 to 48 hours and is painful.  In many cases, the blisters will lead to brownish pigmentation that can last for years.

According to Hiawatha National Forest’s East Zone Botanist, Stephanie Blumer, this invasive plant has become increasingly common across the Upper Peninsula.

“The key for outdoors enthusiasts,” she said, “is to learn to recognize this plant so that when you see it, you can avoid it.”

How can you recognize Wild Parsnip?  While it looks similar to several other carrot family plants, the flowers of Wild Parsnip are yellow and the stem is smooth and green with very few hairs. Its leaves are long, saw toothed, pinnately compound and form a basal rosette during the first year. The leaves are further divided into leaflets that grow across from each other along the stem, with 2 to 5 pairs of opposite leaflets. In its second year from June until mid-July, and sometimes even through late summer, the plant flowers. Its flowers are small and yellow with five petals and there are hundreds per plant. The flowers are arranged in 2-6 inch wide umbels at the tops of stems and branches, and there are usually no bracts, and very small or non-existent sepals at the base of the flowers.

“As Wild Parsnip spreads, more people are coming into contact with it,”” said Deb LeBlanc, West Zone Plant Ecologist for the Hiawatha. She added that individuals who will be working, hiking, or involved in other activities around the plant can reduce the risk of exposure by wearing long-sleeved shirts, gloves, and long pants.

What are your chances of encountering Wild Parsnip?  While it originates from Eurasia, Wild Parsnip has become a common invasive plant in U.P roadsides, ditches, and other disturbed open areas.  Believed to have been introduced to North America by early European settlers who grew it as a tap root; the wild populations are thought to be a result of escaped cultivated plants. Wild Parsnip is a plant that inhabits various growing conditions such as dry, moist, and even wet-mesic prairies, oak-openings, and calcareous fens.

Once it invades open ranges, it begins to take over in waves and spreads rapidly, especially in disturbed areas. This invasive plant is spread through the distribution of its seeds that are carried by the wind, vehicles, equipment, and water. The seeds themselves, are typically large, slightly yellow, ribbed, flat, and round. It is around September through November that the plant will produce its seed and being a monocarpic perennial, once the plant seeds, it will die. However, the seeds can remain viable in the soil for up to four years, thus adding to the difficulties of eradicating the plants existence.

“Wild parsnip has been designated as a State Noxious weed in approximately 35 states. “Besides the obvious health risk, the plant is problematic due to its ecologically invasive habit,”” said LeBlanc.

For further information on Wild Parsnip contact your local Forest Service botanist at 906-387-2512 extension 20 or 906-643-7900.

Gypsy Moth Attacking Michigan Trees…Again

Ugh, they’re back! Or maybe it’s more accurate to say they never left.

Gypsy moth has been a pest to Michigan trees for decades, ever since it was introduced to the state in 1954. While the invasive pest has never been eliminated, some years seem to be worse than others? This year seems to be particularly bad. Why? One word: drought.

Read the below article by Michigan State University Extension to find out how drought can cause booms in gypsy moth populations.

 

Gypsy moth caterpillars once again attacking trees in Michigan

Large numbers of gypsy moth caterpillars strip trees in Mid-Michigan as drought hampers fungal controls.

Barrier band for gypsy moth larva control. Photo by Pennsylvania Department of Conservation and Natural Resources - Forestry, Bugwood.org.

Barrier band for gypsy moth larva control. Photo by Pennsylvania Department of Conservation and Natural Resources – Forestry, Bugwood.org.

 

They are back! A Clinton County resident contacted the Michigan State University Extension Lawn and Garden Hotline to report heavy caterpillar feeding in maples, pines and apple trees. A few trees had lost much of their foliage. A photo of the caterpillars confirmed it is gypsy moth, Lymantria dispar. For Michigan residents that have dealt with gypsy moths in the past, it is an unwelcome sight but one that is not unexpected.

Twenty to 30 years ago, gypsy moth was a plague across Michigan, defoliating thousands of acres of trees each year. Without many natural controls, it wreaked havoc on oaks, pines, maples, birches, apples and many other species. In 1989, a fungal pathogen was found killing off large populations of gypsy moth caterpillars in Northeastern states. This fungus was identified as Entomophaga maimaiga, a natural biological control of gypsy moth in Japan.

Brought to Michigan in 1991, E. maimaiga quickly became a key factor in suppressing gypsy moth across the state. Naturally occurring in soils, it spreads to young caterpillars as they move from tree to tree. Caterpillars begin to die as the fungus grows inside them. The spores from these dying and dead caterpillars spreads by wind infecting other caterpillars. As the season progresses, large infected gypsy moth caterpillars are found dying on tree trunks. Dead caterpillars remain attached to trunks and branches, hanging straight down. E. maimaiga is so effective that areas of the state often go for years without any noticeable damage from this ferocious defoliator.

So why are gypsy moths back in large numbers and feeding on trees? Drought! The fungus cannot effectively reproduce during times of drought. A year ago much of Michigan was in a serious drought from spring to early summer.  This is the time the fungus is dependent on moisture for its development and of course it is also the time gypsy moth caterpillars begin to feed on trees. Callers to the MSU Extension state hotline in 2016 confirmed that more caterpillars were feeding on trees across southern Michigan. Without consistent moisture in the spring, more gypsy moth caterpillars survived into the moth stage to produce larger numbers of egg masses. It was not unexpected to see growing populations of gypsy moth caterpillars this year.

gypsy moth larva

Gypsy moth caterpillar. Photo by Bill McNee, Wisconsin Dept of Natural Resources, Bugwood.org.

 

Drought is the weak link for the Entomophaga maimaiga fungus and in years when this occurs gypsy moth populations begin to grow and impact landscapes and forests. Spring droughts in 2007 and 2012 led to higher population of gypsy moth the following years. The good news is that in most years we do have adequate rainfall in the spring. Many areas in southern and mid-Michigan had consistent rain this past May, allowing for good development of the fungal pathogen.

Inspect plants now for gypsy moth caterpillars and damage. Trees that lose a large percentage of leaves to gypsy moth feeding can become stressed as energy reserves are used to produce a second set of leaves. Conifers may be permanently damaged if totally defoliated, especially pines. Valuable pines and hardwoods in the landscape can be sprayed with insecticides labeled for caterpillars, or trunks of trees can be banded with a sticky material to trap caterpillars as they crawl up and down trees. This may help on individual trees that are out in the open but may have little effect on trees in the woods where insects can move between adjacent trees.

If valuable trees are infested, you can contact an arborist to spray for the caterpillars. You could also choose to let nature take its course.  In my conversation with the gentleman from Clinton County, we discussed how wet conditions in most of mid to southern Michigan this spring should lead to development of the fungus E. maimaiga. He observed that he was already seeing dead caterpillars hanging straight down, which is a symptom of the effect of the fungus on gypsy moth caterpillars. These dead caterpillars infested with E. maimaiga now become the future source of the fungus in this area protecting trees for years to come.

Michigan is a large state with different weather patterns. While one area is in a drought, another site can be experiencing heavy rains. Awareness of where spring drought occurs can provide an early indicator for possible gypsy moth outbreaks. Nature provides many clues if we pay attention.

Oak Wilt Striking Michigan Trees

There is a fungal disease that has made its way into Michigan and is taking out our oak trees. As if we needed another forest pest to worry about, oak wilt has made an appearance in several Michigan counties. This is causing mass clear-cuttings in portions of the state, including in state parks.

The reason? The only way to stop the spread is to cut down all infected trees, and in many cases any oak surrounding an infected tree.

Since it’s relatively new in Michigan, we have an opportunity to help stop the spread. Here are some tips we all can do to help:

  • Watch your trees closely. If something doesn’t look right, report it to the Michigan Department of Natural Resources. It may turn out to be nothing, but it’s better to be safe than sorry.
  • Don’t trim oak trees from April 15 until July 15, or even through the entire summer if you want to err on the safe side. Any injury can create a way for the fungus to get into the tree. This means intentional injuries like trimming, or accidental ones from lawnmowers, weed whips, and storm damage. If you accidentally nick the trunk of your oak trees doing yard work, seal it up with pruning sealer or tree paint.
  • And the last tip we’re going to give is please don’t move firewood. It is tempting to save money and inconvenience by bringing wood with you when you go camping, but this can cause problems by carrying forests pests long distances and bringing them to new areas. Oak wilt is no exception. The fungus spores can live in the bark of firewood and infect healthy trees at your destination. Please buy where you intend to burn!

A Warning for Great Lakes States: A disease called “Oak wilt” is striking Michigan Forests

Oak tree effected by Oak wilt.

By , Great Lakes Now

If you head to Northern Michigan this summer, you might see some disturbing landscapes across the shoreline and in other spots across the state: clear-cutting. In most cases, it’s not because a shopping development or a subdivision is about to be constructed. It’s because of a fast-moving and deadly fungus that takes aim at Oak trees and can kill them in less than four weeks. And the only solution to stop the spread of the disease is to kill the trees it infects.

It’s called “Oak wilt” disease. Great Lakes Now talked with Jenna Johnson who’s a forest technician with AmeriCorps at the Michigan Department of Natural Resources in Cadillac. She says Oak wilt was first discovered in Great Lakes states in the 1940’s. It has caused major damage in Midwestern States like Minnesota but has only recently made its way into Michigan. She says Roscommon, the Gaylord area, Missaukee County, and Kalkaska County are being particularly hard-hit right now.

Beetles spreading Oak wilt

 

Johnson says, “Oak wilt is a vascular disease. It makes the tree unable to absorb water. It starves the tree to death.” She says the tree starts to die the minute it’s infected, and starts dropping all its leaves. She says it strikes Red oaks, Pin oaks and some White oaks. It’s spread by sap-feeding beetles that take aim at freshly wounded trees. And once one Oak tree is infected, all other Oak trees in the area are in danger of being infected.

She says if the tree isn’t cut down and removed from the area – right into the roots- followed by what’s called “vibratory plowing” down at least 5 feet into the ground to destroy the fungus –   Oak wilt could sweep across the state. The DNR says if Oak wilt isn’t stopped by cutting down infected trees, it could continue to spread, possibly killing almost all the Red oaks in Michigan.

At least 21 states are dealing with the disease, but the majority of Oak wilt cases are being discovered in the Midwest.

The DNR says Oak wilt isn’t just spread through live trees. It’s also spread by firewood that still has its bark. That’s why the DNR wants to get the word out this summer that no one should cut any kind of Oak trees – including power companies – from April 15th to July 15th, and there’s a ban on cutting Oak trees for firewood during this time, too. Bill O’Neill, State Forester of Michigan and Chief of the Forestry Division of the DNR   tells Great Lakes Now if you are gathering or buying firewood, “use and buy your firewood locally – get it from the vicinity where you’re going to be using it.” 

For more information go to http://www.michigan.gov/dnr.

Firewood Awareness Month. Why do we need one?

Fall is here! That means that many will be travelling, looking for that perfect fall foliage that makes the covers of calendars everywhere. And there’s nothing wrong with that.  Michigan welcomes all who want to take a gander at her magnificent fall colors. We just ask that you do one thing.

Leave the wood at home.

This goes for everyone, both in-state and out-of-state travelers. It might seem harsh, or that it’s just another excuse to sell firewood, but there’s a good reason for it. Insects can hitch a ride in firewood, either as eggs, larvae, or even as adults depending on the time of year. Right now, a lot of insects are laying eggs that will overwinter and hatch next spring. By bringing your own firewood you may be unknowingly moving forest pests hundreds of miles to cause new devastation next year.

If we have learned anything from the destruction of the Emerald Ash Borer it is that prevention is key. We do not want a repeat of this kind of damage. So it becomes all of our responsibility to be part of the solution, instead of the problem.

By purchasing firewood where you intend to burn it, or even gathering it on site if it’s permitted, is one of the easiest things you can do to help stop the spread of unwanted insects and disease.

That is why this year, for the first time, the nature Conservancy’s Don’t Move Firewood program is teaming up with the U.S. Department of Agriculture – Animal and Plant Health Inspection Service’s (APHIS) Hungry Pests initiative for Firewood Awareness Month. Learn more in the article below.

We all need to do our part to protect our trees.

 

As the Weather Cools, Your Firewood Choices Matter

Don't Move Firewood pests graphic

Wood boring insect pests can continue their development deep within cut wood. They can emerge from wood left to sit outside to infest new areas.

 

This October, the Nature Conservancy’s Don’t Move Firewood campaign and Hungry Pests, an initiative from APHIS, are partnering to present the first-ever Firewood Awareness Month. The cooler nights and quickly approaching fall season brings an increase in RV camping, hunting, and home heating. Firewood Awareness Month looks to raise public awareness about the potential danger of firewood movement as a pest and disease pathway at this high-risk time of year.

Tree-killing invasive insects and diseases can lurk both inside, and on the surface, of firewood. While these insects and diseases don’t travel far on their own, transporting firewood allows them to move hundreds of miles and start infestations in new places, explains APHIS Deputy Administrator Osama El-Lissy.

Pest infestations can impact our forests by killing trees there as well as in our parks and communities. Infestations are also costly to control or eradicate.

Everyone’s firewood choices matter, says Leigh Greenwood, The Nature Conservancy’s Don’t Move Firewood campaign manager. When it comes to protecting our campsites, wildlife habitats, neighborhood trees, and other favorite places, we all have a personal responsibility to slow the spread of forest pests. Firewood Awareness Month serves as the perfect opportunity to inform the public on the different ways they can help protect the places they love.

Firewood in bags

Firewood that has been heat treated is often sold bagged, boxed, or wrapped. Look for a state or federal seal to certify it was properly treated. Photo credit: L. Greenwood, Don’t Move Firewood campaign, The Nature Conservancy

 

This Firewood Awareness Month, everyone can help protect the places they love from the spread of damaging forest pests by making one of these three safe firewood choices:

  1. Buy firewood near where you’ll burn it
  2. Buy certified heat treated firewood (look for a state or federal seal)
  3. Gather firewood on site when permitted

Anyone who will travel from one location to another, including campers, anglers, hunters, and RV owners, should not carry firewood—unless it is heat-treated and certified—to their destination. This can spread forest pests and may also violate state and federal laws, depending on the region. Plan to gather firewood on site if permitted or purchase firewood near your camping destination.

People who use wood to heat their homes or cabins can help by harvesting firewood locally or by purchasing firewood from a reputable dealer who is in compliance with state or regional firewood regulations. Some operations may be unaware of quarantine and movement restrictions, resulting in the unintentional and illegal movement of tree-killing pests.

Tourists, too, can help protect the places they love against the spread of pests. As thousands of “leaf peeping” fall foliage enthusiasts travel to view the changing leaves around the country, they should purchase firewood locally, buy certified heat treated firewood, or gather on site if allowed.

Get state specific firewood regulations and recommendations at Dontmovefirewood.org/map. Visit www.DontMoveFirewood.org or www.HungryPests.com to learn how to help stop the spread of invasive pests and report signs of them to the proper authorities, and use #firewoodmonth to join the conversation on Facebook and Twitter.

Firewood

When buying firewood for home heating, use a reputable dealer in compliance with local regulations. Photo credit: L. Greenwood, Don’t Move Firewood campaign, The Nature Conservancy

The Stink Bugs Are Back

They’re brown, numerous, and annoying. And right now they’re trying to make their way into your homes. Brown marmorated stink bugs.

Every year people are plagued with these pests as they look for warm places to hide for the winter. Unfortunately for us, we’ve made lots of them with our obsession for cozy homes, insulated garages, even storage sheds and barns. All of these provide great protection for these insects during the harsh temperatures of winter.

If you find yourself infested, don’t panic. While irritating, they’re harmless. And there are ways to keep them out of your house.

The article below from Michigan State University Extension gives you a few tips and resources to help.

 

Brown marmorated stink bugs are moving into Michigan homes again

What they are, why stink bugs are entering houses, and what you can do about them.

The brown marmorated stink bug is a shield-shaped, plant-feeding bug native to Asia. It has distinctive banding on its antennae and around its abdomen. Photo: Jeff Wildonger, USDA-ARS-BIIR.

The brown marmorated stink bug is a shield-shaped, plant-feeding bug native to Asia. It has distinctive banding on its antennae and around its abdomen. Photo: Jeff Wildonger, USDA-ARS-BIIR.

It’s that time of year again when brown marmorated stink bugs invade structures humans create looking for a place to hunker down for winter. Since last fall when Michigan residents were asked to report brown marmorated stink bugs in their homes, we now know that brown marmorated stink bugs are well-established as a nuisance pest in homes in the southern Lower Peninsula of Michigan.

What are they doing?

Brown marmorated stink bugs are looking for a protected place to hibernate over winter. They will leave your house again in the spring – if they can find their way back out – to look for plants to feed on and lay their eggs outside.

What are they NOT doing?

They are NOT nesting, laying eggs or feeding on anything or anyone in your house. These are plant-feeding insects with straw-like mouthparts for drinking plant juices – they are harmless to humans and pets.

What do you need to do?

  1. Don’t panic.
  2. Look for gaps around window air conditioners or holes in window screens and block them off – these are easy access points for brown marmorated stink bugs to enter houses.
  3. The easiest, non-toxic way to dispose of them is with a couple inches of soapy water in a bucket – the soap prevents them from escaping the water. Sweep them into the bucket and they will drown in the soapy water, which you can then dump outside. Or you can do the same with a Shop-Vac – add the soapy water to the canister before vacuuming them up with the Shop-Vac.
  4. Report how many you’ve seen at a given location using the Midwest Invasive Species Information Network. If you have trouble entering the information on the Midwest Invasive Species Information Network website, leave a message for Julianna Wilson via email at jkwilson@msu.edu or by phone at 517-432-4766 with your name, address (or nearest crossroads), the date you saw them, and how many you have seen.

The map below shows where we have received reports to the Midwest Invasive Species Information Network of brown marmorated stink bugs in the Lower Peninsula since Sept. 25, 2015.

Map of Michigan counties that have received brown marmorated stink bugs reports

Biology and other tips for managing them in your home: download the free Brown Marmorated Stink Bug (BMSB): Information for Michigan Residents tip sheet from Michigan State University Extension.

Prevent them from entering your home: see “Managing brown marmorated stink bugs in homes.”

Report sightings of brown marmorated stink bugs: see “Report sightings of brown marmorated stink bugs in your home or business.”

Visit MSU’s Brown Marmorated Stink Bug website for 2016 monitoring network reports and additional information.

Hope for the Ash Tree

Experts thought the ash tree was doomed. With the introduction of one tiny insect in 2002, its demise seemed inevitable. The Emerald Ash Borer specifically targets ash trees for their hosts. They lay their eggs under the bark and the larvae wreak havoc, chewing up the tree from the inside, before they emerge as adults and cause destruction to the leaves as they feed and reproduce, starting the cycle all over again.

In the wake of Dutch Elm Disease, many Michigan communities planted mostly ash to replace the dead elm trees, setting the stage. By planting mostly one species, many communities lost nearly all their trees once the beetle reached them. The insect simply flew from one tree to the next, spreading like wildfire. Any tree that was planted or naturally grew in infested areas was almost always attacked once it reached a decent size.

It seemed like a losing battle.

Yet, there may still be hope of having ash trees around.

Hope for ash

An adult ash borer within the wood tissue. Image: Gerald Wheeler

Ash borer leaves a destructive trail through wood tissue. Image: Gerald Wheeler

By Colleen Otte

Experts used to say the number of ash trees lost in Michigan was tens of millions.

Now they say hundreds of millions, according to Deb McCullough, a professor in Michigan State University’s entomology and forestry departments. Still, there’s hope for the ash’s survival.

“In a nutshell, what I found is that [ash] seems to be holding on quite well,” said Dan Kashian, who studies ash tree regeneration.

The mortality varies among species, but now the devastation has become an international epidemic, McCullough said. While some patches are worse than others, it’s hard to find a lot of live ash trees in Lower Michigan and much of the eastern and central Upper Peninsula.

The culprit is the emerald ash borer, Agrilus planipennis Fairmaire, an exotic Asian beetle discovered in southeastern Michigan near Detroit in the summer of 2002. Adult beetles are metallic green and about 1/2-inch long. They hitched rides on ship and plane cargo originating from Asia and moving to Detroit.

“The longest history of the emerald ash borer in North America is right in the greater metro Detroit area,” McCullough said.

Kashian, an associate professor at Wayne State University, found himself in this prime location for assessing the plight of the ash.

“It’s been here longer than it’s been anywhere else, so it’s a good place to study what it’s going to look like, say, in Traverse City in 15 years or 10 years or something,” he said.

The three main ash species in Michigan are green, white and black ash. They grow in very different places, according to Kashian: black ash in swamps, green ash near rivers and white ash in the uplands.

The front of an merald ash borer head. Image: S. Ellis

Kashian is studying how the different species respond to the ash borer. So far, his team has only set up seed traps and other regeneration trackers in 17 pockets in southeastern Michigan that are almost entirely green ash.

For five years, the study quantified how many seeds fell and how many new seedlings took root.

“It looks awful because the big trees are all being killed, and in terms of it ever looking like it did before the emerald ash borer came through, it’s probably never going to happen,” Kashian said. “But the species does not – at least based on what I’ve seen – look like it’s going to disappear, which is what a lot of people were predicting.”

MSU and other leading agricultural researchers, as well as government and non-profit institutions, have created and now support the Emerald Ash Borer Information Network, a multinational effort to share the latest information about the emerald ash borer as it spreads.

The network reports that the insect is established in Windsor, Ontario, was found in Ohio in 2003, northern Indiana in 2004, northern Illinois and Maryland in 2006, western Pennsylvania and West Virginia in 2007, Wisconsin, Missouri and Virginia in the summer of 2008, Minnesota, New York, Kentucky in the spring of 2009, Iowa in the spring of 2010, Tennessee in the summer of 2010, Connecticut, Kansas, and Massachusetts in the summer of 2012, New Hampshire in the spring of 2013, North Carolina and Georgia in the summer of 2013, Colorado in the fall of 2013, New Jersey in the spring of 2014, Arkansas in the summer of 2014, Louisiana in the winter of 2015.

“We will never see emerald ash borer densities at the same level that they were originally, because the carrying capacity of those systems has dropped hugely,” McCullough said. “When the big trees die, you’re not churning out nearly as many beetles, so the populations of the ash borer are going to remain lower for the foreseeable future. Whether they will stay low enough to give some of those young trees a chance to mature, we’ll have to see.”

Kashian said he wouldn’t go as far as to say the ash and the borer have reached an equilibrium.

“But we seem to be approaching some kind of balance with the bug at this population level and the trees hanging on,” he said.

The prevailing story of other studies is that the borer will eliminate ash in Michigan as it spreads. That’s because the studies were done in mixed forests where green ash were dying and different trees grew into the space, said Kashian.

In the pure stands of ash that Kashian studied, the dying green ash only made way for new ash seedlings.

“It’s very dependent on how much ash is there,” he said. “I think the more ash that’s there, the more likely it is to survive. A lot of people think intuitively the opposite – the conventional wisdom is that if it’s a pure stand, the bugs will just go crazy and kill everything.”

In northern Michigan, big stands of white ash are a concern. Though Kashian’s team hasn’t studied white ash yet, he suspects a similar phenomenon in which the trees growing in mixed forests won’t fare as well as those in pure stands.

A parasitic wasp injects its egg in the egg of an emerald ash borer where it will hatch, grow and kill the host egg. Image: Jian Duan

While it’s still early to tell, Kashian said there is some indication that where parasitic wasps were released to control the ashborers, larger ashes survived and more of them regenerated.

It might not be ideal to release a nonnative species, he said, but if we want to maintain nice, big ash trees, it’s something we need to do.

“The most well-funded programs aren’t even talking about stopping the emerald ash borer, they’re talking about slowing it,” Kashian said. “Whether or not (bio control) is cheap is kind of a moot point because there’s not really any other choice.”

For the eight-plus billion ash trees in the forest in the U.S., it’s hard to justify treating with an insecticide, McCullough said.

“It’s just not economically or environmentally appropriate,” she said. “That means you have to look for other options, and right now we don’t have much else other than bio control.”

The Emerald Ash Borer Biological Control Production Facility in Brighton, Michigan, rears Asian wasps that fight the borer.

“We work with the federal entities and the state entities to identify infested sites within each individual state,” said Ben Slager, the manager of the lab facility.

The borer has been identified in 27 states, and the lab has three more to distribute to: Georgia, Texas and Nebraska, Slager said. The tiny, wasp-like parasitoids were first released in Michigan in 2007, and have been released in all eight of the Great Lakes states.

“One of the goals for our agency is to get parasitoids into every infested county,” he said. “Last year, (the lab) put out 1.2 million, the year before that it was 750,000 and we’ve been steadily increasing through the years.”

The Bio Control Production Facility releases three different species of the wasps and is in the process of introducing a fourth. Its production of the fourth species has been ongoing since last fall, Slager said, but while they are doing scheduled releases this season, it’s only on a limited basis since they are still getting their rearing methods and procedures down.

The benefit of the new species is that it can lay eggs in trees with thicker bark because it has a longer ovipositor.