Posts Tagged ‘gypsy moth’

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.

What to Do With Gypsy Moths?

Gypsy moths have been a plague in Michigan for a long time now and likely will be for years to come. That’s the problem with invasive exotic pests, once they’re established in an area they are difficult if not impossible to remove. While we have past the point to prevent a hatch of new ones this year (that happens in May), there are things you can do to control them.

The article below was one I wrote in 2014 for our annual newsletter. It lists several resources that may prove useful if you find yourself battling voracious gypsy moth caterpillars this summer.

 

Gypsy Moth: A New Look at an Old Enemy

By: Jennifer Hunnell, Michigan Arbor Day Alliance

Invasive species have been making news headlines across the country. People want to know what they are, where they are, if they pose a threat to their community, and what they can do about them if they find one.

The new ones are what usually capture everyone’s attention; Asian Carp, Asian Long-Horned Beetle, and Giant Hogweed just to name a few. Emerald Ash Borer makes this list as well. While not exactly new, the fight continues as the Emerald Ash Borer is still spreading into the western states. However, we can’t forget about the invaders that are 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 is a good example. This Eurasian 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. Since female moths don’t fly, their spread across the country has been largely attributed to human transportation of eggs or caterpillars. And while there are several natural factors for population control, including diseases, parasites, and predators, we still get the occasional population boom where they seem to be everywhere. The caterpillars have a voracious appetite and can infest a wide range of broad-leaf trees, but favors oak and aspen. Defoliation by the caterpillars can cause extensive damage and even death of the infested tree if it is old or weakened by disease or stress.

And while eradication of the gypsy moth is a dream of the past, there are some things you can do to control them on your own property.

  • Properly Water and Fertilize – This is your first line of defense. Keeping an eye on your trees and shrubs, making sure they are healthy, will reduce the pests attracted to them and reduce the amount of damage done if they are attacked.
  • Sanitation – Keep your yard as clean as possible. Remove dead branches, stumps, etc. where the adult moths may lay egg masses. Watch out for eggs transported on firewood or recreational vehicles (boats, trailers, RV’s, etc.)
  • Destroy Egg Masses – Gypsy moth egg masses are around for nearly nine months (August – May). Seeking out and destroying egg masses each year will reduce populations.
  • Tree Barriers – Various bands around tree trunks can help prevent caterpillar movement into and out of the tree canopy. Some act as traps (sticky), some as deterrents (slippery). Cloth hiding bands can also be made. These bands serve as hiding places for the caterpillars during the day so you can easily find them.

For more information about gypsy moths or other invasive species, check out these resources:

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.

gypmoth_map

 

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


FOR IMMEDIATE 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 athttp://msue.anr.msu.edu/topic/info/pest_management. 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 www.michigan.gov/foresthealth.

 


Gypsy_moth_caterpillarliving_gypsy_moth_adult

 

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 www.michigan.gov/dnr.