Got Nature? Blog

Purdue Landscape Report: Spotted lanternfly (SLF) has been the subject of a lot of media attention in the last few years.  In the east, states like Pennsylvania and New York have been dealing with heavy infestations since the insect was first detected in 2014.  In Indiana, this invasive planthopper arrived three years ago, infesting two counties on the eastern side of the state.  Since then, the Indiana Department of Natural Resources and Purdue University have been working together to mitigate the spread of this insect as well as educate Hoosiers on what they can do to help.  Spotted lanternfly is still on the move, and this update will help refresh you on how this bug works, and where they are headed.

Figure 1. Upper left: early-instar SLF; upper right: late-instar SLF; bottom left: adult SLF with egg mass; bottom right: uncovered SLF eggs.

Life cycle
Spotted lanternfly is an annual insect, having only a single generation in a year under normal conditions.  The insect goes through incomplete metamorphosis; immature stages, called nymphs, resemble smaller, wingless versions of the adults.  Nymphs will begin to appear in April or May, developing through four instars, until they reach adulthood in late summer.  With each instar, the period in between molting, the nymph will grow larger, develop wingpads, and eventually change color.  Early instars are black with a white dot pattern, while later instars will be bright red with black and white patterning (Fig. 1).  Late instar nymphs are often compared to milkweed bugs or lady beetles.  Once they complete development in the late summer or early fall, they will mate and lay egg masses covered in a protective substance that makes them resemble mud.  Eggs masses will overwinter until the spring, while adult insects will die as temperatures cool.  In Indiana, depending on temperature, adults can be seen as late as early November.

Impact
Spotted lanternfly is a sap-feeding insect, using syringe-like mouthparts to drain nutrients directly from plant tissues.  Like other sap-feeding insects, the activity of SLF wounds the plant, creating openings for various pathogens to exploit.  Feeding by SLF has been shown to reduce overall health of their hosts, reducing their capacity to survive overwintering, and potentially kill the host plant depending on species.  They also produce a sugary waste known as honeydew; while honeydew itself is not harmful, it acts as a growing substrate for sooty mold, which can have a serious impact the photosynthesis of understory foliage as well as attract other nuisance insects.

Spotted lanternfly is a generalist herbivore and can feed on over 100 different species of plant and tree in Indiana.  However, this insect has shown strong preference towards certain species, often with devastating consequences.  The most preferred host is tree-of-heaven, an invasive tree species in North America.  Tree-of-heaven is the primary host of SLF in their shared native range, and the insect appears to experience high reproductive success on it even when they share a new environment.  Grapes are also highly preferred by SLF, and infestations will typically result in overfeeding and the death of the plant.  Black Walnut, American river birch, and various maple species are also at risk of severe damage from this insect.   Evidence has also suggested that maple, when used for syrup production, will experience reductions in yield and quality when attack by spotted lanternfly.

Where are they now?
Spotted lanternfly has been present in Indiana since 2021, first arriving in Huntington and Switzerland Counties.  In Huntington, the infestation occupies a stand of tree-of-heaven next to an industrial parking lot.  Tree-of-heaven moved into the neighboring residential area, allowing SLF to also spread with it. The more rural infestation in Switzerland County was traced to a vehicle transported from Pennsylvania, and the insect has taken advantage of patches of tree-of-heaven in nearby wooded areas.  While both infestations have strongly associated with the insect’s primary host, there is some evidence that SLF is beginning to take advantage of other nearby plants, such as maple.  In the last year, SLF moved a significant distance and has been detected in several more counties, including Elkhart, St. Joseph, Porter, Allen, Dekalb, and Noble Counties.  Most of the activity has been found on tree-of-heaven along rail lines, supporting the idea that the insect is dispersed by rail traffic moving westward out of infested areas.

It’s important to remember that trains aren’t the only vehicles that can have SLF passengers.  These insects, and their egg masses, can be found on just about any surface, including the car you drive to work, the RV you used for recreation, semi-trucks that cross the country, and more.  Purdue Entomology and Indiana DNR are encouraging everyone to inspect their vehicles when traveling through any of the infested areas.  Also check all recreational vehicles and trailers for spotted lanternfly egg masses; if found, scrape them off into a bag or bucket filled with soapy water.  This fall and winter, we also want to encourage everyone to please burn any firewood where you buy it, and please don’t move it off your property if you chop it yourself- especially if you are burning tree of heaven.  Egg masses will stick to firewood and can survive our winters very well.

What can I do?
We are still learning about the spotted lanternfly’s distribution through Indiana, and we need the help of citizen scientists to effectively track the insect’s movement.  If you believe you’ve seen spotted lanternfly, please report it using any of the resources listed below.  You can also feel free to reach out to Bob Bruner, Exotic Forest Pest Educator, by emailing them at rfbruner@purdue.edu, or you can report sightings by calling 1-866-NOEXOTIC.

Original article posted: Spotted Lanternfly is on the Move!.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Spotted Lanternfly Resources:
Spotted Lanternfly Found in Indiana, Indiana Woodland Steward
Spotted Lanternfly – includes map with locations, Indiana Department of Natural Resources Entomology
Report Spotted Lanternfly, Purdue College of Agriculture Invasive Species

Other Resources Available:
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
ReportINvasive, Purdue Report Invasive Facebook posts include webinars and workshops

Bob Bruner, Exotic Forest Pest Educator
Purdue Entomology

As the crisp autumn air settles in and campfires become a seasonal staple, October brings an important reminder: your firewood choices matter. That’s why October is officially Firewood Month, a nationwide campaign to raise awareness about the risks of moving firewood and the spread of invasive forest pests.

Why “Don’t Move Firewood” Matters
Transporting firewood, even just a few miles, can unintentionally spread destructive pests like emerald ash borer, Asian longhorned beetle and spongy moth. These invaders often hide inside or on firewood, threatening Indiana’s forests, parks and urban trees.

The Don’t Move Firewood website offers excellent resources to help you make informed choices. Whether you’re heating a cabin, heading out to hunt, or planning a backyard bonfire, they recommend:

• Buying firewood where you’ll burn it
• Choosing certified heat-treated wood
• Gathering wood on-site when permitted

You can also explore their Firewood Month Toolkit, maps of regulations and a webinar series designed for professionals and outdoor enthusiasts alike.

While October is Firewood Month, the risk of spreading invasive pests lasts well beyond the fall. Many forest pests remain a threat throughout the year. Adults may still be visible until the first hard freeze, and egg masses can be observed from now through June. The spotted lanternfly females lay egg masses in late summer through early winter, often peaking in October. These masses can survive through winter and hatch in the spring. Learn more about the Spotted Lanternfly from the Indiana Department of Natural Resources. This is why it’s important to practice safe firewood habits year-round.

Spotlight on ReportINvasive
Check out the latest post on the ReportINvasive Facebook which reinforces the importance of Firewood Month. ReportINvasive is a trusted source for updates on invasive species in Indiana, and their social media outreach is a great way to stay informed and engaged. Give the Facebook page a LIKE and FOLLOW for future webinars and workshops.

Concerned About Insects? Purdue Extension Entomology Can Help
If you suspect insect damage or want to learn more about forest pests, the Purdue Extension Entomology team is an outstanding resource. Their experts provide science-based guidance on insect identification, management strategies, and outreach materials to help protect Indiana’s ecosystems.

Let’s work together to keep Indiana’s forests healthy and resilient. This October, make the smart choice—don’t move firewood!

More Resources
Spotted Lanternfly – including map sharing locations, Indiana Department of Natural Resources
October is Firewood Awareness Month!, Purdue Landscape Report
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
Cooperative Invasive Species Management Area (CISMA)
Aquatic Invasive Species, Illinois-Indiana Sea Grant (IISG)
Emerald Ash Borer Information Network, Purdue University and Partners
Invasive plants: impact on environment and people, The Education Store, Purdue Extension’s resource center
Entomology Weekly Review, Indiana Department of Natural Resources, Division of Entomology & Plant Pathology
Division of Entomology & Plant Pathology, Indiana Department of Natural Resources

Diana Evans, Extension and Web Communication Specialist
Purdue University Department of Forestry and Natural Resources

Fig. 1. Yellowing mottling damage due to scale feeding. Image: Brian Kunkel, University of Delaware.

Purdue Landscape Report: Christmas tree growers have been struggling with an invasive scale pest called Cryptomeria scale (Aspidiotus cryptomeriae), which is a serious pest of conifers. The scales infest the undersides of the needles and extract plant juices with their piercing-sucking mouthparts. Economic losses are due to the unsightly yellow discoloration and needle drop that occurs from the insect feeding (Fig. 1).

Life cycle: Cryptomeria scale has two generations per year. It overwinters as second-instar nymphs on the undersides of the needles, and in spring (March-April) the nymphs begin feeding again and continue development. They reach maturity by late spring. The adult females are flightless and remain stationary. They have a “fried egg” appearance of a white oval shape with a yellow center (Fig. 2). The adult males are alate, meaning they have wings (Fig. 3). Males fly in the summer, typically in July. They will mate with the females and die shortly after. The females lay eggs in the weeks following the mating flight. Egg hatch occurs around late August. These newly-hatched nymphs are called “crawlers”, because they are mobile and will disperse across the plant to find a new spot to settle and feed. Cryptomeria scale nymphs may not move very far from the female; many settle close to the female. The crawler stage is over by early September, when most have established a feeding site. They will develop through the fall into second-instars and overwinter until the following spring.

Management: Scout for the scale in the late winter when the scales are overwintering and prune infested branches, or remove the entire tree if heavily infested. Lady beetles and parasitic wasps will feed on Cryptomeria scale, so use biorational insecticides to maintain populations of beneficial insects which help control Cryptomeria scale and other pests.

Since Cryptomeria scales are armored scales, horticultural oils are recommended instead of insecticidal soaps for effective management (Quesada et al. 2017). Apply oils before bud break to target overwintering scales. Make sure to saturate the needles fully, especially the undersides of the needles, to smother the scales. For a more aggressive solution, dinotefuran can be applied for control of Cryptomeria scale. Basal bark applications of dinotefuran applied just after bud break were shown to significantly reduce scale populations and actually improved the rate of parasitism from parasitic wasps (Cowles 2010).

Not sure if you Cryptomeria scale or something else? Reach out to the Plant Pest and Diagnostics Lab for identification services!

View the original article on the Purdue Landscape Report website: Cryptomeria scale on Christmas trees.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Purdue Landscape Report: It’s that time again!  With the arrival of warm temperatures and increased rainfall, many of us are getting to work on our lawns, gardens, and landscaping.  Unfortunately, this often comes with discovering what new (or old) invasive species are here to haunt us.  So far this year, the invasive I’ve gotten the most questions on is the Asian jumping worm.  This earthworm’s life cycle tends to experience ‘boom & bust’ years due to their feeding habits, and, anecdotally speaking, we appear to be experiencing an increase in their populations throughout the state this season.  Now is a great time to brush up on our understanding of this organism, and the revisit how it impacts our environment.

Figure 1. The clitellum, the set of pale, milky colored segments, is the reproductive organ of earthworms.

Identification
While Asian jumping worms share a lot of traits with other, less harmful earthworm species, they do have some features we can use to differentiate them from the rest.  Jumping worms tend to be darker in color, since they live either on top of the soil or just under the first layer of plant detritus and get more exposure to sunlight.  Asian jumping worms also have a significantly higher number of bristles, or setae, that they can use to move around.  They can have as many as forty bristles per segment, in contrast to the eight found on other species, giving them the traction they need to wriggle and squirm as violently as they do.  Perhaps the easiest feature we can use to identify them is the clitellum, the organ that contains they reproductive organs.  On Asian jumping worms, the clitellum just looks like a very pale set of segments close to the anterior end of the worm, whereas on most other worms, it’s about midway down the body and saddle-shaped.  Finally, we can detect their presence by changes in our soil.  Asian jumping will not improve soil quality for growing like other earthworms can, but rather change the soil consistency into something like coffee grounds, rendering it unsuitable for growing most crops and ornamentals.

Environmental Impact
As I alluded to above, Asian jumping worms do significant damage to soil quality when left unmanaged.  These earthworms, unlike their beneficial cousins, do not provide ecosystems services like soil aeration or castings that help add nutrients to the soil.  Since they live at the surface, they do not burrow, and their castings lock in nutrients and often get swept away by hydrological events.  Asian jumping worms also tend to gather in large groups whenever they infest an area, resulting in most of the decaying plant material and other organic material being stripped out of the soil.  Often, the only plants capable of developing in those conditions are invasive themselves!

Reporting
We are still learning about the Asian jumping worms spread in Indiana, so we are asking everyone to please report sightings.  You can report them either online by going to the EDDMapS website or you can call 1-866-NOEXOTIC.  We ask that you take a picture and tell us where you were when you saw the worms. You can also check the Report Invasive webpage for up-to-date information on all kinds of invasive species, or reach out to Bob Bruner, Purdue University Exotic Forest Pest Educator, by emailing rfbruner@purdue.edu.  With your help, we can map out this worm and create effective plans to limit its presence in our state.

View the original article on the Purdue Landscape Report website: Asian Jumping Worms: How to ID this soil pest.

Subscribe and receive the newsletter: Purdue Landscape Report Newsletter.

Resources:
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
Landscape & Ornamentals: Bagworms, The Education Store
Purdue Plant Doctor App Suite, Purdue Extension-Entomology
Find an Arborist website, Trees are Good, International Society of Arboriculture (ISA)
ID That Tree – Video Playlist, Purdue Extension – Forestry and Natural Resources (FNR) YouTube Channel
Fifty Common Trees of Indiana, Purdue FNR web page list
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

Bob Bruner, Exotic Forest Pest Educator
Purdue Entomology

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 – The Education Store, Purdue Extension’s resource center
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

The Purdue Plant and Pest Diagnostic Laboratory (PPDL) proudly presents its latest Annual Report, offering a comprehensive overview of the year’s most significant insights, diagnostics, and trends. This essential document covers critical topics such as spruce-tordon uptake, hosta virus X, ophiostoma ulmi, diamond back moth, lettuce slime mold, and bentgrass dollar spot. As an indispensable resource for growers, researchers, and the public, PPDL remains at the forefront of providing expert analysis on plant diseases, insect identification, and environmental concerns throughout Indiana and beyond.

Visit the PPDL Annual Reports webpage to find the 2024 report and view past reports.

About PPDL:
The Plant and Pest Diagnostic Laboratory (PPDL) remains dedicated to helping protect Indiana’s agriculture, the green industry, and individual landscapes, by providing rapid and reliable diagnostic services for plant disease and pest problems. PPDL also provides appropriate pest management strategies and diagnostics training. They are a participating member lab in the National Plant Diagnostic Network (NPDN), a consortium of Land Grant University diagnostic laboratories established to help protect our nation’s plant biosecurity infrastructure.

Resources:
Find an Arborist, International Society of Arboriculture
Diseases in Hardwood Tree Plantings, The Education Store, Purdue Extension’s resource center
Fifty Common Trees of Indiana
An Introduction to Trees of Indiana
Shrubs and Woody Vines of Indiana and the Midwest, The Education Store
Tree Installation: Process and Practices, The Education Store
Forest Improvement Handbook, The Education Store
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
Indiana Department of Natural Resources: Invasive Species
Indiana Invasive Species Council
ID That Tree, Purdue Extension-FNR YouTube playlist
Tree Defect Identification, The Education Store
Tree Wound and Healing, Got Nature? Blog, Purdue Extension – Forestry and Natural Resources

Purdue Plant & Pest Diagnostic Laboratory (PPDL)
Purdue Botany and Plant Pathology

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