Posts Tagged ‘forest health’

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,

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


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,


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

New Hemlock Quarantine Possible

It’s a tiny forest pest that is wreaking havoc across the Appalachian Mountain region and one that could cause the same kind of devastation in Michigan if we’re not careful.

It’s called the hemlock woolly adelgid (HWA), a small aphid-like, sap-sucking insect that is responsible for killing thousands of hemlock trees. It’s difficult to find due to its small size, but can begin killing trees as early as 4 years after infestation. The first reported sighting was near Richmond, VA in 1951. By 2005 it had spread to 16 states from Maine to Georgia.

It has been recently identified in west Michigan; first noticed in Muskegon county, but has also been found in nearby Allegan and Ottawa counties. An import quarantine is already in effect for Michigan, meaning that hemlock cannot be brought into Michigan from an infested state. However, since it has been determined that HWA is in several Michigan counties, an in-state quarantine is being considered. This would mean that movement within Michigan would be regulated, especially within the quarantined counties.

With the estimated 170 million hemlock trees in Michigan, including the virgin hemlock forest at Porcupine Mountains State Park, extra caution is a good thing.


Michigan is preparing to enact interior quarantine due to invasive hemlock tree pest

A recent outbreak of the pest within the state has prompted new legislation which will restrict the movement of hemlock products within Michigan in an effort to control this invasive pest.

Adelgid infested hemlock branches. Photo credit: USDA Forest Service - Region 8 - Southern, USDA Forest Service,

Adelgid infested hemlock branches. Photo credit: USDA Forest Service – Region 8 – Southern, USDA Forest Service,


Over the last several years, in reaction to the outbreak of hemlock wooly adelgid in forest stands across the eastern U.S., Michigan banned the shipment of hemlock trees and wood with bark into the state. However, a recent outbreak of the pest within the state has prompted new legislation which will restrict the movement of hemlock products within Michigan in an effort to control this invasive pest.

The exotic hemlock wooly adelgid insect was first identified in the eastern U.S. in early 1950s. It has systematically spread throughout the Appalachian region and is devastating the hemlock tree forest resource by the thousands. In an effort to help protect the estimated 170 million hemlock trees in Michigan, a ban or quarantine on bringing hemlock nursery stock and wood products with attached bark into the state has been in place for some time and was last revised in 2014.

In spite of the efforts to keep this destructive forest pest out of the state, an infestation has been identified in central West Michigan. First noticed in Muskegon County, closer inspection has identified colonies of the tiny sap feeding pest in neighboring Ottawa and in Allegan Counties as well.


Pale crown appearance with no new growth indicates this tree is under severe attack from Hemlock Woolly Adelgids. Photo credit: James Johnson, Georgia Forestry Commission,

In an effort to control or slow this tree-killing pest, the Michigan Department of Agriculture & Rural Development (MDARD) solicited public comment on a proposed hemlock woolly adelgid interior quarantine. The original draft stated that “the proposed quarantine, movement of hemlock nursery stock, branches, boughs, uncomposted chips, logs and firewood would be regulated. Specifically, movement out of, or within, the three county area would be prohibited except under compliance agreement issued by MDARD. The proposed regulated area includes Allegan, Muskegon and Ottawa counties.” Other counties may be added as the need arises to further limit the spread of hemlock woolly adelgid.

If the quarantine is enacted, the movement of hemlock trees, boughs, firewood, logs or limbs will be prohibited without a compliance agreement. This restricted movement would include movement within these counties from site to site. (Note: A compliance agreement are actions jointly taken by both producers and the State of Michigan to ensure hemlock nursery stock and wood products are free of the adelgid insect.)

For more information on the hemlock wooly adelgid, Michigan State University Extension has a bulletin available. Extension Bulletin E-3300  details the life cycle and highlights the negative impacts from this invasive killer with some available treatment options should landowners identify adelgid colonies in their trees.

In addition, people interested in becoming actively involved in identifying new infestations of this and other potential forest pests are encouraged to become involved in the MSU Extension Eyes on the Forest program by becoming a sentinel tree volunteer.

Gypsy Moth: How to identify it and what you can do

Invasive species across the country have been making news headlines. People want to know what they are, where they are, and if they pose a threat to their community. New ones like Asian Carp, Asian Long-Horned Beetle, and Emerald Ash Borer (while not exactly new, it’s still spreading westward across the U.S.) are what usually capture everyone’s attention. However, we can’t forget about the ones already established, ones that may have fallen off our collective radar because they have been around so long they have become commonplace. The fact remains, they’re still invasive, they’re still a problem, and we need to stay proactive about doing our part to control them.

Gypsy moth has been a long-standing problem in Michigan. They were introduced to the United States in Massachusetts in 1869 and made it to Michigan by 1954.



Lymantria_disparSince the female moths don’t fly, their spread across the country has been largely attributed to human transportation of eggs or caterpillars. While there are natural population control mechanisms in Michigan (disease, parasites, and predators), we still get the occasional population boom where they seem to be everywhere. The caterpillars have a voracious appetite, favoring a wide range of deciduous trees. The defoliation can cause extensive damage and even death of the infested tree if it is old or weakened by disease or stress.


Here are a few resources that may help you if you believe you have a gypsy moth problem:

Michigan State University Extension Gypsy Moth Homeowner’s Guide – identification, life cycle, and control methods

Midwest Invasive Species Information Network (MISIN) Gypsy Moth Fact Sheet

U.S. Department of Agriculture’s Hungry Pests website – current range, signs and symptoms of infestation, what you can do

What to Know Before You Move, USDA Hungry Pests – what to inspect, quarantine areas, moving checklist and tips

Gypsy Moth Still a Problem in Parts of Michigan

Gypsy moth caterpillars making life challenging for Michigan residents

Michigan DNR sent this bulletin at 07/15/2013 09:30 AM EDT

Press Release

July 15, 2013

Contact: Roger Mech, 517-335-4408 or Ed Golder, 517-335-3014

Gypsy moth caterpillars making life challenging for Michigan residents


Michigan residents in northern parts of the state are noticing loss of leaves on oak, aspen and maple trees. The prime culprit contributing to this defoliation is the gypsy moth. Department of Natural Resources forest health officials report that, while the most obvious defoliation is currently heaviest in Crawford, Oscoda, Otsego and Montmorency counties, it is likely that gypsy moth caterpillars are causing similar problems on a local scale in other areas of the Lower Peninsula.

“Gypsy moth caterpillars are nothing new to our state,” said DNR forest health specialist Dr. Robert Heyd. “They’re a recurring challenge. We most often see defoliation in the season following a particularly drought-heavy year like we experienced in 2012. Many forest pests tend to target trees that are weakened – perhaps from drought – or otherwise not in optimum health. The number one thing people can do to reduce the effects of pests like gypsy moth is promoting tree health.”

Regular watering and avoiding damage to roots and bark go a long way in helping trees fend off the effects of defoliation. Likewise, periodically removing dead and dying trees in woodlots keeps remaining trees growing strong.

Heyd explained that gypsy moth populations surged across the state during the 1980s and 1990s, defoliating many woodland areas. At that time, the moth was fairly new to the state and, like any introduced species, its population grew rapidly without natural control from parasites, pathogens and predators.

During this period, the Michigan Department of Agriculture and Rural Development worked with local communities to conduct aerial spraying to reduce gypsy moth nuisance in areas with high caterpillar numbers. When done properly, using biological insecticides, aerial treatment can help make life more tolerable during outbreaks, without affecting the natural enemies that eventually bring gypsy moth populations under control.

While these spray programs are no longer conducted by the state, natural enemies of the gypsy moth are now well-established across Michigan and are actively helping to reduce populations. Two pathogens in particular – the nucleopolyhedrosis virus (NPV) and a fungus, Entomophaga maimaiga – are killing gypsy moth caterpillars in large numbers across much of the Lower Peninsula. Wet spring weather in many areas has given these organisms the upper hand, helping them to develop and spread quickly.

Surviving gypsy moth caterpillars are currently spinning cocoons to transform into moths later in July. With the caterpillar stage nearing an end in most areas, it’s too late for spraying to help.

The good news is that defoliated trees are already beginning to develop new leaves to replace those that were eaten. And even heavily defoliated trees will recover without serious long-term effects.

Heyd said gypsy moths rarely kill trees in Michigan.

“Historically, only trees already suffering from problems like drought, old age or root damage are at risk,” he added.

To learn more about gypsy moth caterpillars, visit the MSU Extension website at More detailed information is also available in a MSUE bulletin that covers the origins, lifecycle and other facts about the gypsy moth caterpillar.

For more information about the DNR’s Forest Health Program, visit




The Michigan Department of Natural Resources is committed to the conservation, protection, management, use and enjoyment of the state’s natural and cultural resources for current and future generations. For more information, go to

Things Are Not Always As They Appear

Despite the fact that Michigan, as well as the Great Lakes region as a whole, has hundreds of exotic invasive species, the public generally only knows about the headliners – the big ones like Emerald Ash Borer and Asian Carp that get a lot of press because of their widespread or flashy destruction.  But there are several more that do just as much damage without getting the face time and household name recognition.  As a side note, it should be known that not all non-native species are invasive – think about most of the trout species and all of the salmon in the Great Lakes for example.  These are not native to this region, but do not out-compete other species or throw off ecological balance.

Because our existing issues are so diverse, we are constantly on the lookout for new invaders; the ones at our backdoor in nearby states, waiting to pounce on an opportunity to invade a new area.  It is always good to be aware of your surroundings since the key to getting ahead of a potential exotic is early detection.  But if you find something you think doesn’t belong, double-check before you panic.  Things in nature are not always what they seem at first.  There are several native animals and plants that look quite a bit like their exotic counterparts, but hold no threat to us, our yards or the ecosystem.  Below are just a few examples of this look-alike confusion.

Don’t Be Fooled By Emerald Ash Borer Look-Alikes – Michigan State University Extension

Aquatic Invasive Plant, Hydrilla – New York Invasive Species


Massachusetts Introduced Pests Outreach Blog

Hey – That’s Not ALB!

Over the past couple of weeks, our pest reporting website has been deluged with reports from people who are worried they’ve spotted the dreaded Asian longhorned beetle. Turns out almost all of these reports can be blamed on a look-alike, the whitespotted sawyer:
whitespotted sawyer beetle

The whitespotted sawyer (Monochamus scutellatus) is a native beetle that attacks diseased and damaged pine trees. It emerges from trees earlier in the season than Asian longhorned beetles (“ALB”), which is not expected to be seen in Massachusetts until the end of June. Both beetles are black with white spots and long, black-and-white banded antennae, but sawyers are not as shiny as ALB, they have fewer and duller white markings, and they all have a distinct, white, half-circle marking at the top center of their wing covers. Use this image to compare:

If you think you’ve seen an Asian longhorned beetle, or you aren’t sure what you’ve seen, you should always report it. Try to get a photo or capture the insect if you can.

Invasive Species Information, MI Department of Agriculture & Rural Development – Giant Hogweed

Examples of Giant Hogweed

How Do You Know If It’s Really Giant Hogweed? A number of common plant species resemble Giant Hogweed, but there are ways to tell them from the real thing. Here are a few guides you may find useful:

If you have seen a plant that appears to be Giant Hogweed and need help identifying it, send an email to, along with any pictures, so that the pictures can be examined by professional staff of the Michigan Department of Agriculture & Rural Development. (Email pictures of the whole plant, leaves, flower head, and where the leaf joins the stem.)  You can also call 1-800-292-3939.

Giant Hogweed is a public health hazard that ranks up there higher than poison ivy, poison oak, and poison sumac in respect to its potential to harm humans. The reason for concern is that the sap from this plant can cause a severe skin reaction known as photo-dermatitis or photo-sensitivity. The reaction can happen up to 48 hours after contact. After coming in contact with the sap, the skin blisters when exposed to sunlight. Contact with the eyes can lead to temporary or possibly permanent blindness. The weed can be especially troublesome for children that may find the long stems attractive to play with. There are accounts from Great Britain about instances where children suffered from severe skin reactions after playing with the hollow stems as pea-shooters, telescopes and even play swords. If you do come into contact with the plant, and especially the sap, you are advised to wash the affected areas immediately, keep the exposed area out of direct sunlight and seek medical advice.

Besides these public health concerns, Giant Hogweed is also reported to be invasive under certain conditions. It does especially well in disturbed soils and also along waterways where seeds can be spread long distances. Large colonies have been known to form from a single plant, where an abundance of seeds coupled with shoots arising from the roots gives rises to dozens of offspring. Weed specialists have reported that once it becomes established, it takes up to five years to completely get rid of a colony due to regrowth from seeds and roots.

This unwanted plant is found on the Federal Noxious weed list. This means that it is illegal to sell or transport it across state lines, a violation punishable by fines. Florida, North Carolina, Oregon and Washington also regulate giant hogweed as a noxious weed.

Giant Hogweed was introduced into North America in the early 1900s. Its native range is Central Asia, although now it now occurs throughout the United Kingdom, Australia, Europe, parts of Canada and the United States. It is suspected to have made its way into this country as an ornamental. Its size made it somewhat of an oddity, and gardeners that wanted something unique imported it.

Giant Hogweed has been confirmed in 11 counties in Michigan:  Branch, Calhoun, Gogebic, Ingham, Jackson, Kalamazoo, Kent, Manistee, Oakland, Ottawa and Saginaw. The rest of Michigan should be watchful for this species. It’s reported distribution in North America includes Maine, Michigan, New York, Pennsylvania and Washington in the U.S. and in the Canadian provinces of British Colombia and Ontario. Small colonies of giant hogweed have recently been found in Indiana, Maryland, Ohio and Vermont where eradication is underway.

If you have seen a plant that appears to be Giant Hogweed and need help identifying it, send an email to, along with any pictures, so that the pictures can be examined by professional staff of the Michigan Department of Agriculture & Rural Development. (Email pictures of the whole plant, leaves, flower head, and where the leaf joins the stem.)  You can also call 1-800-292-3939.

A few informative web sites are:


But of course, if you see something you think you need to report, by all means do so.  It is better to be safe than sorry.  If you live in or around Michigan, here are a couple of good resources:

Midwest Invasive Species Information Network

Michigan Department of Natural Resources – Invasive Species Specialist Contact List