Got Nature? Blog

Purdue Landscape Report: Recently, there has been an uptick in questions related to one of Indiana’s most notorious invasive pests: the emerald ash borer.  Homeowners, businesses, even professionals have asked if ash trees are still present in Indiana, and if the insect is still a threat to our ecosystem.  Emerald ash borer wreaked significant havoc among Indiana’s hardwoods, and a person could be forgiven for believing that there are no ash trees at all in our state, but this is simply not true.  Ash still survives in Indiana and can be found both as ornamental plantings and in untended woodlots; unfortunately, emerald ash borer is also still present and just as deadly to them as ever.  The question of protecting ash versus removal them is complex, but entomologists and tree specialists have learned from this insect’s invasion.

Figure 1. Side view of EAB, John Obermeyer

The emerald ash borer (Agrilus planipennis), a wood-boring insect native to Asia, is responsible for decimating ash (Fraxinus spp.) throughout the United States and elsewhere.  In Indiana, this insect’s presence was confirmed in 2004, though it had probably been in the state for some time before then.  Since its arrival, Hoosiers have been forced to watch as ash trees have rapidly declined and died due to the insect’s feeding and life cycle.  The insect lays its eggs in crevices in the bark of an ash that is 8 to 10 years old, and after hatching, the new larvae begin to bore through the tree’s cambium tissue. The tree relies on its cambium tissue to transport water and nutrients and supply cells for new growth.  Often, the only signs of the insect’s presence are a reduction in canopy coverage and D-shaped exit holes in the bark, indicating adult emergence.  As time goes on, however, the tree will continue to lose canopy, experience limb death, and often have large chunks of bark detach. Unprotected trees will typically die within 2 to 5 years of infestation.  Dead and dying ash trees represent a serious hazard to health and property as infestation will leave them extremely brittle. Brittle ash will often fall during weather events or even collapse over time as limbs fall off.

While emerald ash borer did significant damage to ash tree populations in Indiana, they did not destroy the population entirely.  While virtually all untreated trees will eventually become infested, saplings with a trunk diameter of ½ to 1 inch will remain untouched, allowing annual replacement of trees to continue.  Since the initial invasion killed so many trees, the borer’s populations have been proportionally reduced as well due to a lack of a food source.  This combination of factors has created a cycle of growth and infestation that allows both populations to survive, but at significantly lower levels as compared to the period of the initial infestation.  Unfortunately, this also means that emerald ash borer is now a permanent fixture in the hardwood ecosystem in Indiana.

Figure 2. This photo illustration shows three ash trees in Bloomington, Indiana, with different levels of canopy lost to the emerald ash borer. (Purdue Tree Doctor app illustration/Cliff Sadof)

While many may believe ash trees are a total loss, there are still options to protect ash tree and even rescue ash that have already been infested.  The first step in this process is to determine the extent of damage in a given tree.  As the cambium tissue is consume by ash borer larvae, the tree will experience a steady loss of canopy and limb death.  The proportion of lost canopy makes a great indicator for treatment viability.  For example, a tree that has only lost 10% of its canopy will normally respond well to treatment.  As more canopy is lost, recovery is more challenging, until the tree has lost %30 of canopy coverage.  After that point, there is very little chance that a rescue treatment will be successful, and removal will most likely be necessary.  It is also important to remember that limb death may occur; these limbs will not recover and will need to be removed to avoid any potential hazards.

There are several insecticides with varying ranges of efficacy that can be used to manage emerald ash borer.  These include imidacloprid, dinotefuran, azadirachtin, and emamectin benzoate. Several studies have been conducted to find the best combination of chemical and application type, such as the difference between using a soil drench compared to a trunk injection. While all of the above chemicals can be effective against the insect, the combination of emamectin benzoate applied through a trunk injection offers the best, longest lasting protection from infestation.  This combination has a durable effect lasting for two years under dense infestations.  However, the reduction in emerald ash borer populations have spread the distribution of the insect thinner, and longer intervals between treatments are possible.  A ten-year study conducted by Purdue University demonstrated that treating trees once every three years provided sufficient protection from the beetles, while also showing that 4 to 5 years after last treatment coincided with an increase in damage to the trees.  This same study also found that by six years post-treatment, the trees would decline to the point of making removal a necessity.  This research concluded that increasing time between intervals after three years increased the risk of catastrophic damage due to emerald ash borer activity, thus the recommendation for three-year intervals.

Ultimately, many will see this as a financial issue: the cost of treatment over time against the cost of removal to avoid potential damages.  The above study estimated the cost of treating a single tree with an emamectin benzoate injection at $300 per treatment. Since treatment only needs to happen once every three years, the cost per year per tree would be $100, approximately.  Tree removal was estimated between $1800 and $3600, depending on tree location and other factors.  Also consider replacement costs if you wanted to continue to grow ash in that area, and how long the tree would need to grow to match the size of the tree you just replaced.  Additionally, add in any treatment costs to make sure it survives infestation.  When looked at from this angle, maintaining regular treatment on rescuable trees would appear to be the most cost-effective route for managing ash.  Any treatment plan should be discussed with a professional, such as a certified arborist.

Read the original article posted in the Purdue Landscape Report April 2025 Newsletter: Revisiting Ash Tree Protection.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
New Hope for Fighting Ash Borer, Got Nature? Purdue Extension-FNR
Invasive Pest Species: Tools for Staging and Managing EAB in the Urban Forest, Got Nature?
Emerald Ash Borer, Purdue Extension-Entomology
Emerald Ash Borer Tools & Resources – Purdue Extension Entomology
Planting Your Tree Part 1: Choosing Your Tree, Purdue Extension YouTube Channel
Tree Planting Part 2: Planting a Tree, Purdue Extension – Forestry and Natural Resources YouTube Channel
Indiana Invasive Plant List, Indiana Invasive Species Council, Purdue Entomology
Landscape Report Shares Importance of Soil Testing, Purdue FNR Extension
Find an Arborist website, Trees are Good, International Society of Arboriculture (ISA)
Tree Risk Management – Got Nature? Blog, Purdue Extension – FNR
ID That Tree – Video Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
Purdue Arboretum Explorer
Conservation Tree Planting: Steps to Success, Purdue Extension – FNR YouTube Channel
A Woodland Management Moment, Playlist, Purdue Extension – FNR YouTube Channel
Woodland Stewardship for Landowners, Playlist, Purdue Extension – FNR YouTube Channel
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
Cooperative Invasive Species Management Area (CISMA)
Report Invasive, Purdue Extension
Native Trees of the Midwest, Purdue University Press
Professional Forester, Indiana Forestry Woodland Owners Association
Forest Improvement Handbook, The Education Store

Bob Bruner, Exotic Forest Pest Educator
Purdue Entomology

Purdue Landscape Report: Sawflies are frequent pests in the landscape that attack a wide variety of plants, from ornamental flowers to large trees. You might start to see them damaging plants around this time of year as the first generations hatch and begin to feed on foliage. They are often mistaken for caterpillars, which are the larval stages of butterflies and moths (Order Lepidoptera). However, sawflies are actually wasp-like insects (Order Hymenoptera).

Let’s review how to tell them apart. Products that are labeled for caterpillars do not always work on sawflies, so proper identification is important.

• The most reliable characteristic are the prolegs. Sawflies have 6+ pairs of prolegs, or false legs, while caterpillars have < 6 pairs of prolegs. (Fig. 1)
• When disturbed, sawflies will lift their posterior into an “S” shape. Caterpillars don’t display this behavior. (Fig. 2)

Integrated management recommendations

Early in the year, before hatching starts, look for sawfly oviposition on your plants. This will vary depending on the species of sawfly. For example, the European Pine sawfly eggs look like yellow-orange spots evenly spaced on the needles (Fig. 3). The Bristly Roseslug sawfly uses her ovipositor to cut a slit into the leaf petiole where she inserts eggs. The gooseberry sawfly lays eggs on a leaf vein (Fig. 4).

If the eggs are readily visible, manual removal will help reduce the populations. This is best accomplished in early spring before the eggs hatch. Use a tool to smash the eggs, or prune of the affected plant material.

You may not notice any problem on the plant until you start to see holes appearing in the foliage. Monitor regularly in the spring for holes and “window pane” damage (Fig. 5). This is the time of year when sawflies are hatching, so don’t wait any longer to check your plants. Sawfly management is best accomplished when the larvae are still small. Prune or shake off the larvae from the plant, or spray with a biorational material so as not to disturb natural enemies and cause a secondary pest outbreak later in the summer.

For more information on sawfly biology, check out this five-minute video: Slaying Sawflies with Purdue Plant Doctor.

Specific management recommendations can be found on the Purdue Plant Doctor website. Type “sawfly” into the search and click on the species you would like to read more about!

Read the original article on Purdue Landscape Report: Sawflies: the caterpillar pests that are not caterpillars.

Purdue Landscape Report: The bitter winter cold has finally passed us (or has it? It’s hard to tell in the Midwest)! The days are getting warmer and longer, and that means the insects are coming out of their overwintering stages. As you prepare for your landscaping and gardening this year, are you implementing preventative measures for pests? Now is the time to think about those strategies to minimize the damage to your plants.

Preventing pest issues is foundational to integrated pest management. The first step is always to start with healthy and clean plants. Don’t be afraid to bring a hand lens to the store and check for those hard-to-see pests! You don’t want to bring a problem home. Next, remember that many pests will thrive due to improper watering, light conditions, or fertilization. Avoid these issues by reviewing the recommendations for your plants and consulting a soil test. (Read more about why soil tests are essential!)

Finally, which pests/diseases do you anticipate? What are the most common pests on the plants in your landscape? Perhaps you have had issues in past years and know what to expect. Review the biology of these pests and consider implementing preventative measures now. Let’s look at a couple of examples of frequent landscape pests and some management options you can add to your list of spring preparations.

Spider Mites

Spider mites overwinter on the host plant or in leaf litter. Around this time of year, cool season mites such as spruce mites and boxwood mites are the dominant issue. Check your plants now for these spider mites, and scout regularly to make sure populations aren’t getting out of control. A rainy spring will help keep the pressure low. If you have to spray, avoid chemicals that will harm natural enemies, which are vital to spider mite management. (Learn more about spider mite management: Spider Mites on Ornamentals; and check out the Purdue Plant Doctor Quick Guide: Managing Spider Mite Mayhem)

Bagworms

Bagworms overwinter as eggs in the bags left on the tree. They’re frequent pests of arborvitae, junipers, and several other trees and shrubs. Take action now to prevent an infestation in the summer that requires costly pesticides. Manually remove the bags from your tree and drown them in soapy water. (Learn more about bagworm management: Bagworms).

Lace Bugs

Lace bugs may overwinter as eggs or adults, depending on the species. They become active again in the spring, so now is a good time to check for these pests. Focus on the undersides of the leaves where the pests are found. Lace bugs prefer hosts planted in sunny areas with a lack of plant diversity, so consider including some flowering plants in your landscape to provide pollen and nectar to beneficials. (Learn more about Lace bug management from the Purdue Plant Doctor Quick Guide: Managing Lace bugs).

What pests do you encounter in the landscape? Take a moment to review their biology and your options for preventative management. Be proactive now and reduce your pest problems for the season ahead. Read the original article, Insects are waking up – are you prepared?

Alicia Kelley, Cooperative Agricultural Pest Survey (CAPS) Coordinator
Purdue Extension – Entomology

Purdue Landscape Report: The elm zigzag sawfly (EZS), Aproceros leucopoda, is a non-native insect recently detected in several midwestern states. Originally from eastern Asia, this insect is rarely considered a problem in its native range, having several natural enemies and environmental factors able to keep it in check.

Figure 1. Elm zigzag sawfly adult, Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org

However, when in new landscapes, aspects of this insect’s life cycle enhance its ability to spread across new habitats and do significant damage to its host plant, the elm tree. EZS was first detected outside of its native range in Europe in 2003. Then, in 2020, it was found in North America for the first time in Quebec. It has since been detected in several states in the US, spreading first through the Northeast before entering the Midwest. It has not yet been detected in Indiana, but has been in the surrounding area.

Elm zigzag sawfly is a member of the insect order Hymenoptera, which includes bees, ants, and wasps. More specifically, sawflies belong to a suborder known as Symphyta, whose members are noted for a broad-waisted appearance and a saw-shaped ovipositor. Sawflies are a fairly common group of insects, though observers will often overlook them or confuse them for other insects. Adult EZS are generally small, darkly-colored insects that are easy to write off as ‘just another black bug’ you see around the garden or yard (Fig. 1).

Figure 2. Elm zigzag sawfly larva feeding, Gyorgy Csoka, Hungary Forest Research Institute, Bugwood.org

They resemble wasps, but possess a broad waist with no narrowing of space between the thorax and abdomen, and they lack a stinger. EZS larvae closely resemble caterpillars in both form and feeding habits, with pale green coloration, a black stripe that runs down the length of the body, and dark T-shaped markings on the legs (Fig. 2). The larvae, like moth and butterfly caterpillars, will also possess six pairs of fleshy prolegs that are lost upon reaching maturity. While the larvae bear chewing mouthparts to consume the leaf material of many kinds of plants, the adults are nectar and pollen-feeding. It should be noted that EZS larvae chew zigzag patterns into elm leaves, thus the common name of the insect. Like bees and wasps, sawflies also possess wings, but are typically lazy fliers, choosing to fly only during warm, sunnier periods of the day.

View the rest of the article here: A New Threat to Elms in North America

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Intro to Trees of Indiana: American Elm, Got Nature? Blog, Purdue Extension – FNR
Intro to Trees of Indiana: Slippery Elm, Got Nature? Blog, Purdue Extension – FNR
ID That Tree, Playlist, Red Elm, Siberian Elm, Winged Elm, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
ID That Tree, Playlist, Purdue Extension – FNR YouTube Channel
Invasive Species Playlist, Playlist, Purdue Extension – FNR YouTube Channel
A Woodland Management Moment, Playlist, Purdue Extension – FNR YouTube Channel
Woodland Stewardship for Landowners, Playlist, Purdue Extension – FNR YouTube Channel
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
Cooperative Invasive Species Management Area (CISMA)
Report Invasive, Purdue Extension
Episode 11 – Exploring the challenges of Invasive Species, Habitat University-Natural Resource University
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – FNR
Native Trees of the Midwest, The Education Store, Purdue Extension’s resource center
Investing in Indiana Woodlands, The Education Store
Forest Improvement Handbook, The Education Store

Bob Bruner, Exotic Forest Pest Educator
Purdue Entomology

Figure 1: Spongy moth caterpillar, credit to John Obermeyer.

Purdue Landscape Report: Spring is always a wonderful, if somewhat chaotic, time of year in Indiana.  Between the heavy rains and beautiful flowers blooming, the months leading up to summer can make your head spin.  While we enjoy the trees greening out and watch out for storms, we need to be aware that spring awakens other organisms, many of which have a major impact on our lives.  This time of the year introduces a host of insect species hatching from eggs, emerging from cocoons, or returning from their overwintering nap, and many of those species mean bad news for our trees.  One of the most impactful species we deal with in Indiana is Lymantria dispar, or the spongy moth.

The spongy moth, so named for the sponge-like egg masses they lay in the early fall, is an invasive species belonging to family Erebidae, a large group of moths that include species such as the woolly bear we see every year in Indiana.  Spongy moth is a native to Eurasia, and historical record shows it has caused problems throughout Europe as early as the seventeenth century.  In the late nineteenth century, an amateur entomologist and would-be entrepreneur brought spongy moth to North America in a failed attempt to create a new silk moth hybrid.  Inevitably, the insect escaped captivity and has since spread through several states over the last century, including the northern portion of Indiana.

Figure 2: Mating spongy moth adults, credit to John Obermeyer.

Spongy moth is a generalist pest that strips leaf tissue from many species of trees, though it has a particular preference for oak.  Like all butterflies and moths, the larva, or caterpillar, is the damaging form of this insect.  Spongy moth caterpillars bear chewing mouthparts they use to consume leaf tissue, but they do not attack wood or root systems of their hosts.  Adults are non-feeding and only survive long enough to reproduce.  Spongy moth can produce large populations each year and move quickly across a landscape, creating sudden infestations and near-complete defoliation in those areas.  While trees will typically recover after losing a significant portion of their leaf tissue, repeated infestations will make a host tree more susceptible to disease, reduce resilience, and potentially lead to death.

Like other moths and butterflies, spongy moth has well-defined life stages that can be used to easily identify them.  Caterpillars will begin to appear between mid-April and early May and can be identified by their hairy appearance, distinct black, blue, and red coloration, and the tendency to move up and down the surface of a tree (Fig. 1).  Male larvae will develop through five instars, while female larvae will grow over the course of six instars.  Larvae will enter the pupal stage midsummer and spend approximately ten to twelve days developing. The pupae of this insect are darkly colored and lack the silk cocoon seen in other species.  Adult male moths will emerge in the latter half of the summer season, followed by female moths about a week later.  The moths can be identified by the pattern on their wings: a black chevron associated with a dot on a pale white or cream background (Fig. 2).  Male moths will have large, feathery antennae and are capable of flight, while females are flightless with smaller antennae.  Adult moths will only survive for a few days to reproduce and lay sponge-like egg masses, which will overwinter and hatch the following spring (Fig. 3).

Figure 3: Spongy moth egg mass on tree, credit to John Obermeyer.

Management of spongy moth often involves work by state and federal agencies, such as the Indiana’s Department of Natural Resources.  Within the Hoosier state, the DNR has quarantined several northern counties to prevent movement of materials that could potentially spread spongy moth even further.  They also conduct yearly mitigation programs to eliminate infestations that are outside of the quarantined area.  Indiana DNR, specifically the Division of Entomology and Plant Pathology, posts information on all mitigation efforts as well as hosts public meetings so residents understand what treatments are used for spongy moth management, and how it will affect their community.

Most organizations, including Indiana DNR, typically use two methods to control spongy moth: mating disruption and Btk applications. Mating disruption uses the moth’s biology against it by confounding its ability to locate a mate.  Spongy moths, like many species, use a chemical signal called a pheromone to attract potential mates; male moths follow the trail of pheromones emitted by a female.  By filling an area with the pheromone, the male moths become unable to follow individual chemical signals, resulting in fewer eggs being laid for the next spring.  Pheromones are also highly species-specific, ensuring little to no impact on other organisms. In Indiana, the chemical used for mating disruption is applied aerially to cover a significant area, and the chemical used is made of food grade materials that break down easily.

Btk applications are also done aerially, coating foliage with a selective pesticide that only affects moth and butterfly species.  Btk is a protein derived from a native soil-borne bacteria (Bacillus thuringiensis kurstaki) and works by damaging the internal lining of an insect’s gut after being consumed.  This is a pesticide that is commonly applied to all manner of crops, persists only for a short time in the environment, and only harms insects.  It also has the benefit of having minimal impact on pollinators, especially when applied using label directions.

While spongy moth is a serious challenge, there are some options you can use to protect your natural spaces.  The first option, and perhaps the most important, is to be vigilant.  If you live in or near an infestation, get into the habit of checking your trees for egg masses starting in the late summer through the fall.  When you find egg masses, check for small pinholes in the sponge-like covering; the hole is created by a beneficial parasitoid wasp that uses the caterpillars as hosts for their young.  You can also destroy egg masses by using a horticultural oil labeled for that purpose, or by scraping off the egg masses into a bucket of soapy water.  Also be watchful of egg masses being laid on homes, firewood, or the sides and undersides of vehicles that move through infested areas.

Larvae will begin to appear in late April, with warmer temperatures encouraging populations to hatch earlier.  One method of controlling larvae is to use burlap banding as a trap to capture larvae moving up and down the surface of the tree trunk.  This can be done by tying a folded piece of burlap around the trunk of the tree at approximately chest height.  Caterpillars, attempting to hide from predators during the day, will crawl into the folds.  Once the late afternoon arrives, the caterpillars can be removed and destroyed by dumping them into soapy water.  You can also use sticky substances in an effort to capture the caterpillars by coating a tree at chest height with it, but this method has several drawbacks.  Any substrate that is sticky enough to capture spongy moth caterpillars will also capture any other insect, beneficial and damaging, and could potentially catch small mammals and birds as well.

If you plan to use pesticides, May through June is the best time to apply.  Biological pesticides such as Btk, spinosad, and others, are available for homeowner use, as well as systemic insecticides such as dinotefuran and emamectin benzoate.  However, given how widespread the caterpillars can be and the heights they can reach, using some insecticides may not be feasible or may require professional assistance.  Homeowners and property managers should consult certified arborists to learn what options will be best, and use pesticides as per the label directions.

While spongy moth is now a permanent part of our ecosystem, we still want to limit its ability to move into new parts of Indiana.  If you live outside of quarantine areas and find an egg mass, caterpillar, or adult moth, report them by contacting the Indiana Department of Natural Resources at 1-866-NOEXOTIC, or by emailing DEPP@dnr.in.gov; make sure to include pictures and location.  You can also consult your local Extension office for assistance in finding arborists, speaking with specialists, or getting problem insects identified.

Original article posted: Purdue Landscape Report.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Spongy Moth, Indiana Department of Natural Resources
The Spongy Moth in Indiana, Purdue Extension – Entomology
Invasive Species, Playlist, Purdue Extension – FNR YouTube Channel
Report Invasive Species, Purdue Invasive Species
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Pest Management, The Education Store
Protecting Pollinators: Why Should We Care About Pollinators?, The Education Store, Purdue Extension resource center
Subscribe Purdue Extension-Forestry and Natural Resources YouTube Channel

Bob Bruner, Exotic Forest Pest Educator
Purdue Entomology

Purdue Landscape Report: It’s that time of year when we remind everyone to watch for spotted lanternfly (SLF) infestations. Spotted lanternfly is an invasive insect first detected in Pennsylvania in 2014, and has since spread throughout the eastern USA. Its preferred host is the invasive Tree-of-Heaven, but it also feeds on a wide range of important plant species, including grapes, walnuts, maples, and willows.

Early instar-Photo credit Richard Gardner, Bugwood.org

Late instar -Photo credit Richard Gardner, Bugwood.org

There are two known populations of SLF in Indiana. The first population was found in 2021 in Switzerland County, and the second population was found in Huntington County in 2022. The Indiana Department of Natural Resources (IDNR), Division of Entomology and Plant Pathology, has launched a delimiting survey throughout the two counties to delimit its range and monitor for activity.

Egg hatch was confirmed in Huntington County and Switzerland County in mid-May at the two known sites. A few adults have been caught about one mile south of the core infestation site in Huntington; however, there are not any new infestations reported as of July 2023. IDNR employees have completed several egg scraping events at the infestation sites, removing over 16,800 egg masses so far this year. That’s over 672,000 eggs!

Adult-rest & late instar -Photo credit Richard Gardner, Bugwood.org

Adult Spotted lanternfly Photo credit-Rebekah D. Wallace, University of Georgia, Bugwood.org

Finding this invasive insect early is crucial to preventing its spread as long as possible. Currently, SLF nymphs are in their 1^st-3^rd instar, so watch for small, black, white-spotted bugs on Tree-of-Heaven. Later instars are black and red with white spots. The adults are about 1 inch long, with very brightly colored wings. The forewings are light brown with black spots, and the underwings are a striking red and black, with white band in between the red and black. When at rest, the adult SLFs appear light pinkish-grey.

Report any suspect findings at ReportINvasive.

To view this full article and other Purdue Landscape Report articles, please visit Purdue Landscape Report.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Spotted Lanternfly Found in Indiana, Indiana Woodland Steward
Spotted Lanternfly Feeds on Over 70 Plus Plant Species, Purdue Extension – Forestry and Natural Resources (FNR)
Spotted Lanternfly – includes map with locations, Indiana Department of Natural Resources Entomology
Spotted Lanternfly is on the Move!, Purde Landscape Report
Spotted Lanternfly, Indiana Department of Natural Resources Entomology
Invasive plants: impact on environment and people, The Education Store, Purdue Extension’s resource center
Woodland Management Moment: Invasive Species Control Process, Video, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
Invasive Species, Playlist, Purdue Extension – FNR YouTube Channel
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – FNR
Report Invasive, Purdue College of Agriculture – Entomology

Alicia Kelley, Cooperative Agricultural Pest Survey (CAPS) Coordinator
Purdue Extension – Entomology

Governor Eric Holcomb has proclaimed February 25th to March 2nd as 2024 Invasive Species Awareness Week in Indiana.

This serves as an important reminder for Hoosiers to be aware and report potentially devastating invasives.

This proclamation states “invasive aquatic, riparian and terrestrial species influence the productivity, value and management of land and water resources in Indiana and the cost to prevent, monitor and control invasive species costs Indiana millions annually and after habitat destruction, invasive species are a great threat to biodiversity and threaten the survival of native plants and animals and interfere with ecosystem functions by changing processes like fire, nutrient flow and flooding”.

It continues with “invasive species impede industry, threaten agriculture, endanger human health and are becoming increasingly harder to control as a result of rapid global commercialization and human travel; and invasive species are as significant threat to almost half of the native species currently listed as federally endangered.”

As Invasive Species Awareness Week starts Sunday, February 25th, the Indiana Department of Natural Resources (IN DNR), Purdue Extension-Forestry and Natural Resources and the Indiana Invasive Species Council will answer any questions you may have.

For Questions:
Ask an Expert, Purdue Extension-Forestry and Natural Resources
Invasive Species – Indiana Department of Natural Resources (IDNR)
Indiana Invasive Species Council – Includes: IDNR, Purdue Department of Entomology and Professional Partners
Cooperative Invasive Species Management Area (CISMA)

Report and Learn More About Invasive Species –
Great Lakes Early Detection Network App (GLEDN) – The Center for Invasive Species & Ecosystem Health
EDDMaps – Early Detection and Distribution Mapping System
Purdue University Report Invasive Species, College of Agriculture

Check Out Our Invasive Species Videos –
Subscribe: Purdue Extension-Forestry and Natural Resources (FNR) YouTube Channel
Invasive Species YouTube Video Playlist includes:

• Asian Bush Honeysuckle
• Burning Bush
• Callery Pear
• Multiflora Rose
• Invasive Plants Threaten Our Forests Part 1: Invasive Plant Species Identification
• Invasive Plants Threaten Our Forests Part 2: Control and Management

More Purdue Extension-FNR YouTube Video Series –
Woodland Management Moment:

• Against Invasives
• Garlic Mustard
• Autumn Olive

Woodland Stewardship for Landowners:

• Common Buckthorn
• Japanese Barberry

ID That Tree:

• Invasive White Mulberry
• Invasive Siberian Elm
• Invasive Tree of Heaven

More Resources –
FNR Extension Publications, The Education Store:

• Invasive Plant Species: Tree of Heaven
• Invasive Plant Species: Oriental Bittersweet
• Invasive Plant Species: Wintercreeper
• Japanese Chaff Flower
• Kudzu in Indiana
• Mile-a-minute Vine

Purdue Landscape Report:

• Alternatives to Burning Bush for Fall Color
• Now is the Time to Identify Callery Pear

FNR Extension Got Nature? Blog:

• Woodland Invaders
• Invasive Species: the Good News and the Bad News

Don’t Miss These Resources:
Episode 11 – Exploring the challenges of Invasive Species, Habitat University-Natural Resource University
What Are Invasive Species and Why Should I Care?, Purdue Extension-FNR Got Nature? Blog
Emerald Ash Borer Information Network, Purdue University and Partners
Aquatic Invasive Species, Illinois-Indiana Sea Grant (IISG)
Invasive plants: impact on environment and people, The Education Store, Purdue Extension’s resource center

Purdue Extension-Forestry and Natural Resources

Purdue Landscape Report: A new invasive insect of concern has been identified in the state of Georgia. In August of 2023, Georgia’s Department of Agriculture, along with the USDA, confirmed the presence of the yellow-legged hornet, Vespa velutina, outside of the city of Savannah. To date, this is the only confirmed identification of this insect in the United States; it has already established in Europe, the Middle East, and parts of Asia outside of its native range.  V. velutina is a native of the subtropical and tropical regions of southeast Asia, and it is not yet clear how it arrived in North America. Much like the northern giant hornet, previously known as the Asian giant hornet or ‘murder hornet’, this insect will attack honeybee hives in search of food and represents a potential danger to the beekeeping industry.

Figure 1. Yellow-Leg Hornet. Image Credit: Allan Smith-Pardo, Invasive Hornets, USDA APHIS PPQ, Bugwood.org

Yellow-legged hornets are predators and will regularly attack honeybees to provide food for their young, though it is possible they could attack other, similar species.  Since honeybees concentrate their numbers in hives with a lot of in-and-out traffic, they provide an excellent opportunity for the hornets to hunt and provide food for their young.  The hornets are effectively ambush predators, waiting in front of hive entrances and capturing workers with their legs as they leave the hive. The hornets then dismember the bees, returning to their young with only the thorax, which contains the largest amount of protein. However, it is believed that yellow-legged hornets only represent a lethal threat to weaker hives that are already experiencing problems; it is also too early to tell how already-existing honeybee issues, such as mite and disease issues, will interact with the presence of this insect.

The yellow-legged hornet, much like other members of Order Hymenoptera, is a social insect. They create oval or egg-shaped nests in trees that can house as many as 6,000 individuals. Colonies are composed of a foundress and her young, who become the workers within the colony.  Female hornets will overwinter within tree hollows, leaf litter, or other environmentally stable locations, and once spring arrives, they start their own colony and give birth to new workers who care for young and hunt.

As with any new invasive species, it is critical to successful identify it and differentiate it from other species of wasps and hornets that we experience in the Midwest.  At a glance, the yellow-legged hornet is barely discernable from European hornets, yellowjackets, and similar insects; they possess aerodynamic shapes with heavy yellow and black color patterns like many of their cousins. The most easily identified trait is their namesake: the legs of this insect tend to be black closer to the body, with the lower half of the leg bright yellow. The segments of the abdomen follow a similar pattern, with those segments closer to the center of the body being dominated by black, steadily becoming more yellow as you reach the tip of the abdomen. The yellow-legged hornet is also approximately an inch in length, with reproductive individuals sometimes reaching an inch and a half.

While remaining observant will be critical to reporting any invasive species, there are a few things to keep in mind about the yellow-legged hornet. This insect has only been found in one location in Georgia; no other states have any sightings or confirmed reports of this insect. There is also no evidence the insect has established a population in Georgia, there is only one confirmed sighting. The best course of action for now is to be vigilant and report any potential sightings by calling 1-866-NOEXOTIC, or you can contact our local Purdue Extension educator for assistance.

To view this full article and other Purdue Landscape Report articles, please visit Purdue Landscape Report.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
Invasive Species, Playlist, Purdue Extension – FNR YouTube Channel
Report Invasive Species, Purdue Invasive Species
What are invasive species and why should I care?, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources
Pest Management, The Education Store
Protecting Pollinators: Why Should We Care About Pollinators?, The Education Store, Purdue Extension resource center
Ask The Expert: What’s Buzzing or Not Buzzing About Pollinators , Purdue Extension – Forestry & Natural Resources (FNR) YouTube Channel
Purdue Pollinator Protection publication series, Purdue Extension Entomology
Subscribe Purdue Extension-Forestry and Natural Resources YouTube Channel

Bob Bruner, Exotic Forest Pest Educator
Purdue Entomology

Tom Creswell, Plant & Pest Diagnostic Laboratory Director
Purdue Botany and Plant Pathology

Cliff Sadof, Professor, Ornamental, Pest Management
Purdue Entomology Extension Coordinator

Purdue Landscape Report: The emerald ash borer (EAB), Agrilus planipennis, is still one of the most damaging insect pests ever to invade North American forests. Unlike most native boring insects, this beetle can attack and kill relatively healthy ash trees. In Indiana cities we found this insect capable of killing most of the unprotected ash trees within 6 to 10 years.  Nearly 20 years after its first detection in Indiana (2004), trees still need to be protected to keep them alive. The benefits of these living ash trees easily justify the cost of monitoring them. We provide answers to common questions people have about the need for continued treatment.

• I have had a tree care specialist treat my ash trees for the last 10 years. What will happen to these trees if I stop this service? If your trees are still healthy, they were probably treated with injections of emamectin benzoate.  Initially we recommended treating trees once every 2 years. This was especially helpful during the initial invasion when each newly infested tree was producing hundreds of beetles per year.  Now that most of the untreated ash trees are dead in Indiana, there are fewer emerald ash borers to attack the surviving ash trees. Research clearly shows that treating trees once every 3 years is enough to keep ash trees alive. Increasing the time between treatments beyond 3 years will increase the risk of losing your trees.

We recently completed a 10-year study in Indianapolis, where large ash trees were treated at 3-year intervals (2013 and 2016), Although they were well-protected through 2019, we saw a slight increase in damage 4 and 5 years after the last injection (2020 and 2021).  By the 6^th year trees after the last treatment (2022), trees declined to the point that they were a safety hazard.  Overall, spring treatments were more effective than fall treatments.

• Is it worthwhile to continue treating my trees? The simple answer is YES, especially if you think about the costs of the alternatives over time. Consider the following choices:
  • Homeowner tree removal vs treatment. Suppose you had ash tree that was whose trunk diameter was 30 inches. If you were to have that tree and its stump removed, the cost could easily be $1800.   If an ash tree is near your house or other valuable structure special precautions need to be taken to keep limbs from causing damage. These protective measures add greatly to the labor costs and could easily double the removal costs ($3600). In contrast, to keep that tree alive, you would have to inject that tree once every three years at a cost of $300 (assuming the fee is $10/ diameter inch).  In other words, the $1800 -3600 you pay to remove the trees would provide 18-36 years of enjoying your tree!
  • Homeowner tree replacement vs treatment. Trees grow slowly. Most add a bit less than a half an inch per year of diameter to the trunk. So, if you add $500 on top of the removal costs to plant a new tree ($2300- $4100), the same money would provide 23 to 42 years of tree enjoyment. Moreover, the tree you planted would only be half the size of the original ash tree in 30 years.

For the full article please visit Purdue Landscape Report: Should ash trees still be protected from emerald ash borer?

Resources:
New Hope for Fighting Ash Borer, Got Nature? Purdue Extension-FNR
Invasive Pest Species: Tools for Staging and Managing EAB in the Urban Forest, Got Nature?
Emerald Ash Borer, Purdue Extension-Entomology
Emerald Ash Borer Tools & Resources – Purdue Extension Entomology
Planting Your Tree Part 1: Choosing Your Tree, Purdue Extension YouTube Channel
Tree Planting Part 2: Planting a Tree, Purdue Extension – Forestry and Natural Resources YouTube Channel
Indiana Invasive Plant List, Indiana Invasive Species Council, Purdue Entomology
Landscape Report Shares Importance of Soil Testing, Purdue FNR Extension
Find an Arborist website, Trees are Good, International Society of Arboriculture (ISA)
Tree Risk Management – The Education Store, Purdue Extension’s resource center

Bob Bruner, Exotic Forest Pest Educator
Purdue Entomology

Cliff Sadof, Professor, Ornamental, Pest Management
Purdue Entomology Extension Coordinator

The clitellum, the set of pale, milky colored segments, is the reproductive organ of earthworms.

Purdue Landscape Report: Asian jumping worms, a group of invasive earthworms, have gained a significant amount of media attention in the last several weeks, and for good reason.  Unlike the nightcrawlers and other earthworms we know, Asian jumping worms do not improve soil health to the benefit of plants.  Instead, jumping worms (also called crazy worms, snake worms, or ‘Alabama jumpers’) almost completely strip nutrients out of soil, altering the soil structure and severely impairing the ability to develop many kinds of plants. After they are done with an area, Asian jumping worms leave behind soil that has a texture similar to that of coffee grounds and very low nutritional value. On top of this, Asian jumping worms are capable of reproducing asexually, allowing their population to grow very rapidly and making them an invasive species of some concern.

Identification
The good news is that Asian jumping worms are not well-suited to Indiana’s environment.  They aren’t capable of surviving winters in any life stage except as an egg, meaning their activity periods are limited to late June to the first hard frost of the year.  If you see worms outside of this period, it’s highly unlikely an Asian jumping worm.  There are also a few traits the worms have that you can use to visually confirm their identity.  First off, Asian jumping worms are accurately named; when handled, they writhe and thrash similar to snakes, setting them apart from common earthworms and nightcrawlers.  Jumping worms also tend to have drier skin that has an almost iridescent appearance, as compared to the slimy, moist texture of the beneficial earthworms we need for good soil health.  The most consistent feature is an organ known as the clitellum, or the reproductive organs of worms.  On common earthworms, this looks like a saddle-shape that partially covers several segments, is normally reddish-brown, and is raised off the surface of the body.  On an Asian jumping worm, however, the clitellum is indistinguishable from other segments, save for their pale, milky color.

To view this article and other Purdue Landscape Report articles, please visit Purdue Landscape Report.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
The Purdue Landscape Report
Purdue Landscape Report Facebook Page
Gardeners Asked to be Vigilant This Spring for Invasive Jumping Worm, Purdue Extension – FNR Got Nature? Blog
Fall webworms: Should you manage them?, Purdue Landscape Report
Mimosa Webworm, The Education Store, Purdue Extension resource center
Sod Webworms, Turf Science at Purdue University
Bagworm caterpillars are out feeding, be ready to spray your trees, Purdue Extension Forestry & Natural Resources (FNR) Got Nature? Blog
Purdue Plant Doctor App Suite, Purdue Extension-Entomology
Landscape & Ornamentals: Bagworms, The Education Store
What are invasive species and why should I care? (How to report invasives.), Purdue Extension – FNR Got Nature? Blog
Indiana Invasive Species Council
Ask An Expert, Purdue Extension-Forestry & Natural Resources

Bob Bruner, Exotic Forest Pest Specialist
Purdue Department of Entomology