All posts by pliesch

IDL Highlights, Invasive Species

A New Tool To Help Track Invasive Insects in Wisconsin

The United States Department of Agriculture (USDA) declared April to be Invasive Plant Pest and Disease Awareness Month. To support this effort, the University of Wisconsin Insect Diagnostic Lab recently launched a new Wisconsin invasive insect mapping page to help track invasive insects in the state.

If you’ve followed this blog for a while, you’ll notice that quite a few of my posts focus on invasive insects.  Why?  In part, it’s because these non-native insects tend to be new or emerging issues and a key role of the UW Insect Diagnostic Lab is to help identify and track new and trending insects in the state. In addition, these invasive insects can sometimes cause significant damage or capture our attention for other reasons.  In a typical year, I see 2-3 new non-native insects show up in Wisconsin, which really adds up over time.  For every species that has arrived here, many more are making progress towards the state (e.g., spotted lanternfly). In other cases, non-native insects show up completely out of the blue.

What’s the big deal with non-native insects?
Non-native insects can cause harm in many different ways:
Introducing the new mapping page:

Because of the impacts mentioned above, it’s helpful to track invasive species so we can better understand where they may be having impacts, and also to get the word out about new detections and allow folks to take appropriate action.  To help in this regard, the IDL’s new invasive insect mapping page hosts a series of maps showing the known county-level distributions of a select list of invasive species.

These particular species have been included due to their relatively recent arrival in Wisconsin, and the ability to track them on a county-by-county basis.  Keep in mind that many other non-native insects can be found in the state, but some of these have been around a long time, are now widespread, and tracking on a county-by-county basis is no longer feasible or helpful (e.g., Japanese beetle, European paper wasps, German yellowjackets, European earwigs, and many more).

The maps on this page will be updated when new detections occur, and additional species maps will be added over time.  If you believe that you’ve observed one of the listed insects in a county where it has not been documented or a new invasive insect species, please collect evidence (physical specimens and/or digital images) and contact me to work on officially confirming the detection.  An example entry from the map page can be found below:

Example entry from the new Wisconsin Invasive Insects Mapping page
Caterpillars, In the News, Invasive Species, Tree Insects

Spongy moth: an old pest with a new name

The spongy moth, Lymantria dispar has recently been in the news because of its new name. If you haven’t heard of the “spongy moth” before, it’s probably because you learned of this insect as the “gypsy moth”. It’s the same exact creature, just with a new common name.

Why the change? The word “gypsy” in this insect’s name was originally a reference to persons of Romani descent—“the popular name of the gypsy was no doubt suggested by the brown, tanned kind of color of the male” [Forbush & Fernald, 1896]. In 2021, the Entomological Society of America’s Better Common Names Project started to review the common names used to communicate about insects. Common names that include derogatory or inappropriate terms are being assessed. After a lengthy review process, the term “spongy moth” was ultimately decided upon to describe Lymantria dispar—and fittingly so. The beige egg masses of this insect have a soft, spongy consistency. In French-speaking parts of its range, this species has long been known as La Spongieuse for this very reason. Thus, you’ll be hearing more about the “spongy moth” over time as the term “gypsy moth” is phased out from educational/government websites and other resources.

Spongy moth caterpillar. Photo credit: PJ Liesch, UW Insect Diagnostic Lab

In addition to the name change, the spongy moth should be on our radar for other reasons. Despite being in Wisconsin for decades, this pest can still be a serious defoliator of hardwood trees, both in yards and forested areas. From the period of 2014 – 2020, spongy moths haven’t been much of an issue. An important reason for this is a beneficial fungus known as Entomophaga maimaiga. This fungus was introduced from Japan and it is strongly associated with the spongy moth. Although it took some time to make an impact in the US, this fungus is now viewed as an important “check” on spongy moth populations. Spring rains encourage this fungus, which can cause high mortality amongst spongy moth caterpillars. However, in many parts of Wisconsin we saw an unusually dry year in 2021 which likely curbed the impacts of this fungus. As a result, I saw an increase in cases and reports of spongy moth caterpillars and their damage, adults, and egg masses at the UW Insect Diagnostic Lab last year and Wisconsin also saw a subtle uptick in defoliation of forested areas.

Defoliation (acreage) due to the spongy moth in Wisconsin over time. Source: Wisconsin DNR Forest Health 2021 Annual Report

As illustrated in the chart above, spongy moth populations can be very dynamic and can explode under the right conditions—leading to extensive defoliation. The egg-laying strategy of this species plays an important role in this dynamic. Adult female spongy moths deposit egg masses that can easily contain upwards of 1,000 eggs. In late summer and fall of 2021, I saw plenty of reports where trees contained dozens of egg masses, which could turn into tens of thousands of hungry caterpillars this spring.

Adult female spongy moth depositing eggs. The spongy beige egg mass can easily contain 1,000 or more eggs. Photo credit: Ryan Hodnett via Wikipedia.

Luckily, there’s still a bit of time to take advantage of this knowledge as the young caterpillars typically don’t become active until late April or early May. In the meantime, removal or destruction of the egg masses could help reduce local populations. While often found on trees, the egg masses can also be located on just about any surface in a yard—stacked boards, sides of structures, piles of firewood, and even on vehicles. Don’t delay if you noticed spongy moth activity in your area last year, since it won’t be long before the caterpillars are out and active this spring.

Reference: Forbush, E. H. and C.H. Fernald. 1896. The gypsy moth. Porthetria dispar A report of the work of destroying the insect in the commonwealth of Massachusetts, together with an account of its history and habits both in Massachusetts and Europe.  Boston, Wright & Potter. 495pp.

Beetles, Odd Insects

UW-Madison and the Chamber of Flesh-Eating Beetles

Unbeknownst to most students, employees, and visitors at UW-Madison, there’s a room of flesh-eating beetles on campus.  An unmarked door on Bascom Hill leads to the chamber more formerly known a the Dermestarium, which serves a rather peculiar yet specific purpose.  No need to worry though—this isn’t 1999’s The Mummy.  Rather, these insects are actually quite helpful in the way that they’re used.

A fitting entryway to the chamber of flesh-eating beetles. Photo credit: PJ Liesch, UW Entomology.

Most insects are actually helpful in one way or another and provide ecosystem services as pollinators, predators, parasitoids, decomposers, or in other roles.  Humans have also figured out some pretty unique ways in which insects can help us out.  For example, mealworms can eat and break down certain types of plastics and are being looked at as a way to help reduce man-made waste materials.  In the legal realm, knowledge about insects is used to help solve crimes—a field known as forensic entomology, which dates back nearly 1,000 years.  In the case of UW-Madison and many other universities and museums, a specific type of beetle is used to help  clean skeletal remains for research, teaching, and display in zoological museums.  

The beetles in the UW Dermestarium are known as hide beetles (Dermestes maculatus) and they’re especially fond of dried-out, protein-rich materials such as remnants of muscles, sinew, fur, feathers, and similar materials.  Out in nature, such insects do play a role in the natural break down of animals remains—but not right away.  Rather, much of that initial work is left to the larvae (maggots) of blow flies (Family Calliphoridae) and flesh flies (Family Sarcophagidae).  Hide beetles and close relatives from the “carpet beetle” group (Family Dermestidae) show up days, weeks, or even months later once the remains are drier.  

Adult hide beetle (Dermestes maculatus). Photo credit: Udo Schmidt via Wikipedia.

In a museum setting, hide beetles can be helpful in the preparation of skeletal remains.  With their small size (roughly 1/4-inch long) , these insects use their mandibles to efficiently remove leftover bits of tissue from tiny nooks and crannies.  For a human trying to prepare remains, such a task would be tedious and may not be feasible for some structures (such as the inside of a skull).  However, a tank of these beetles can easily clean skeletal remains in a matter of days with relatively little effort required, other than maintaining correct ambient conditions for them. 

Skeletal remains in the UW Dermestarium; many larvae can be seen in the box in the photo. Photo credit: PJ Liesch, UW Entomology.

Interestingly, hide beetles and close relatives like the larder beetle (Dermestes lardarius) can be found in our own homes as well.  Their presence poses little risk to humans, but could indicate the presence of a dead rodent or bird in a structure.  Such insects can also develop on a range of protein-rich materials ranging from dead insects in a window sill to human and pet foods and they can occasionally be a pest in home pantries.  Historically, such insects were notable pests of dried meats and cheeses in storage. If you’re curious to know more about these and other insects associated with our homes and everyday lives, Richard Jones has an excellent book on the topic: House Guests, House Pests: A Natural Hisotry of Animals of the Home.

A more detailed history of UW-Madison’s Dermestarium can be found here.

   

Aquatic Insects, IDL Highlights, Odd Insects, Phenology, Uncommon Insects

Insects on the Snow

Despite the season, there’s a surprising number of insects and related arthropods that can be found on the snow during the winter months here in the Midwest.  Such creatures have fascinating life histories and special adaptations (such as natural “antifreeze”or cryoprotectants) that allow them to not only survive, but remain active at low temperatures.  Even these adaptations have limitations and winter insects generally aren’t active if temperatures are below ~20˚F (-7˚C).  Most activity occurs on mild winter days when temps close to or just above freezing.

If you’re curious to learn more about the stories behind these winter creatures and others, I’d encourage you to check out Bernd Heinrich’s Winter World: The Ingenuity of Animal Survival. Read on to learn about some of our commonest “winter” insects in Wisconsin and nearby states:

Snow Fleas: If you follow this blog, you might recall the example of snow fleas from two winters ago.  These dark-colored springtails (Collembola) can sometimes be abundant enough to give large swaths of snow a sooty appearance.  Snow fleas can be common on mild winter days and if I’m out cross-country skiing in the Northwoods, I’m often more surprised if I don’t spot any.

Up-Close View of a Snow Flea. Photo Credit: Daniel Tompkins via Wikipedia

Snow Flies: One of the weirdest examples of a “winter” insect would be “snow flies” from the genus Chionea.  Despite their spider-like appearance, snow flies are actually a type of wingless Limoniid crane fly.  Being wingless and generally slow moving might sound like an easy target for predators, but by being active at cold temperatures these insects can actually avoid the many predators that feed upon related flies during the warmer months.  Interestingly, their physiology is so specialized, that these unusual insects can be active between about 20˚F (-7˚C) and 32˚F (0˚C), but if it’s a warm winter day with melting snow it can actually be too hot for them!  If you’d like a more detailed look at these insects, check out J.R. Schock’s article in The Kansas School Naturalist.

Snow fly (Chionea sp.) on the snow in northern Wisconsin. Photo credit: PJ Liesch, UW Insect Diagnostic Lab

Winter Crane Flies: I occasionally get reports of “swarming mosquitoes” on winter days, and perhaps you’ve bumped into a cloud of tiny delicate flies out in the snowy woods or on a mild fall or spring day.  What you’ve likely encountered are winter crane flies (Family Trichoceridae).  These delicate flies are related to mosquitoes but have no interest in blood.  The adults are simply trying to mate and the larvae are scavengers.  

A winter crane fly (Family trichoceridae) that landed on the snow. These can be spotted flying on mild fall, winter, and early spring days. Photo credit: PJ Liesch, UW Insect Diagnostic Lab

Snow Scorpionflies: In my mind, one of the more elusive winter insects is the snow scorpionfly.  Despite having “scorpion” in the name, these aren’t scorpions (or true flies for that matter).  Rather, they belong to a small order of insects (Mecoptera), which includes some bizarre examples, such as the common scorpionflies, hangingflies, and earwigflies.  Like the snow flies, the snow scorpionflies are also flightless and simply wander about on the snow when conditions are right.  In the Midwest, we only have two species from this group Boreus brumalis and Boreus nivoriundus, and both species are associated with mosses.

A snow scorpionfly. Elusive, but fascinating creatures. Photo credit: PJ Liesch, UW Insect Diagnostic Lab.

Aquatic insects: If you’re near open streams or rivers during the winter months, certain aquatic insects can sometimes emerge and be found on the snow.  Caddisflies and stoneflies are two of the commonest examples.  I recall ice climbing one winter’s night at Governor Dodge State Park west of Madison and reaching the top of a frozen waterfall only to spot dozens of adult “aquatic” insects active on the snow.  The conditions must have been just right that evening, as I also saw hundreds of tiny Cynipid wasps (from oak galls) on the snow as I descended the access trail from the climb.

Caddisfly on the snow near a Northwoods stream. Photo credit: PJ Liesch, UW Insect Diagnostic Lab

Spiders: Hexapods aren’t the only arthropods getting in on the winter fun.  Species from at least a half-dozen families of spiders can occasionally be spotted on the snow on mild winter days.  They might be pretty lethargic, but it’s still interesting to see creatures like that out-and-about on the snow.  The video clip below shows a spider I spotted on the snow in Northern Wisconsin on New Year’s Eve a few years ago when the air temperature was right around 30˚F (-1˚C).

 

  

IDL Highlights, In the News, Invasive Species, Medical Entomology, Ornamental Pest, Wasps and Bees

Looking back at 2021 at the UW Insect Diagnostic Lab

What a year it’s been. Things seemed like they were getting back to normal this past summer, only for the Omicron variant to pop up and say—not so fast. Despite all the ups-and-downs, services have carried on at the UW Insect Diagnostic Lab in one way or another through the second year of the COVID pandemic. Things have changed a bit and these days I’m on campus much more than a year ago. Throughout the pandemic, demand for services at the IDL has remained high with over 2,400 ID requests in 2021.

Early 2021—The UW Insect Diagnostic Lab was still mostly closed to visitors at the time. Campus services were mostly back to normal by the start of the fall semester on campus. Photo credit: PJ Liesch, UW Insect Diagnostic Lab.

Since COVID first popped up, there have been some subtle shifts in lab statistics—an increase in the percentage of samples solely involving digital images (vs physical specimens) and an overall increase in the proportion of cases coming from the public. Considering the pandemic, this makes sense. Over the last two years, campus buildings and the IDL have been closed to visitors at various points, meaning that clients couldn’t drop off samples. In other cases, it might have been tough to make it to a post office or the UPS store to ship a sample in. Likewise, with many folks working from home, it likely led to more time out in yards and gardens, or visiting local parks or hiking trails—and more time to notice insects.

Looking back at the cases from this last year, 2021 was a unique year due to our unusually hot and dry weather conditions in Wisconsin. Based on data from the Wisconsin State Climatology Office, Madison was quite warm and saw an extra ~500 growing degree days in 2021, but was down about 15 inches of precipitation for the year. Some parts of the state were even hotter and/or drier than Madison and most of the state was categorized as either unusually dry or in some stage of drought during the year [US Drought Monitor].

Drought conditions in Wisconsin as of late December, 2021. It’s been an unusually dry year around the state. Map source: Drought Monitor, UNL.

The weather conditions this year led to some shifts in the insects and related arthropods seen at the UW Insect Diagnostic Lab. A pest that had been relatively quiet the last decade, Lymantria dispar (formerly known as the “gypsy moth”), thrived with the dry conditions this past spring. In “rainy” years, a beneficial fungus (Entomophaga maimaiga) can “kick in” to help keep their numbers in check. If 2022 is another dry year, we could be in store for even more problems from this invasive species. Certain mites also thrived this year and I saw a large number of cases of eriophyid mites causing damage to plants ranging from coneflowers to garlic. Springtails weren’t necessarily more abundant (they feed on decaying plant matter and thrive under damp conditions), but I suspect the hot & dry conditions sent them looking for any place darker, damper, and cooler.  This led to lots of reports as they were trying to invade structures.

We’ll likely continue to see the impacts of the 2021 drought for some time.  Plants, including established trees and shrubs, also suffered from the drought and this will likely lead to an increase in reports of “secondary” insect pests in the next few years. Certain insects can be generally “well behaved” and leave healthy plants alone, only to attack stressed and weakened plants.  As an example, cases of the two-lined chestnut borer (a notable pest of oaks) often increase 1-3 years after a drought, and I’m expecting to see more cases in the coming years.

In the realm of medical entomology, it was a good year for ticks both in Wisconsin and other parts of the US. Black flies (Family Simuliidae) had another strong year in many parts of the state, although calls about these were shifted a bit earlier than in previous years (likely due to an “early” spring). If there’s a silver lining to the drought, it’s that mosquito pressure was down in Wisconsin for much of the summer. As we received a bit more rain in the latter half of summer we saw some late season activity, but disease pressure remained low (only three  West Nile Virus cases in Wisconsin, compared to 50+ in a “bad” year). As recreational and work-related travel increased a bit more in 2021 compared to 2020, I did see an uptick in reports of bed bugs.

With the Asian giant hornet garnering attention in the news for the second year in a row, I continued to see lots of reports of cicada killer wasps, pigeon horntails, great golden digger wasps, and other large insects.  Unfortunately, with the sensationalized hype about “murder hornets” (ahem—New York Times…) I had plenty of reports of other large harmless insects that were killed simply because they “looked big and scary” (one particular photo of a tomentose burying beetle comes to mind…).  Overall, the Asian giant hornet story was really pretty quiet this year, with a limited amount of activity in a small part of the Pacific Northwest.  As of December 2021, the Asian giant hornet has not been found in Wisconsin or anywhere close to us.

Insects like the pigeon horntail (Tremex columba) may be large (as far as insects go), but are completely harmless to humans. I saw plenty of cases where members of the public contacted me after killing such insects simply because they looked “big and scary”.  When publishers such as the New York Times use sensationalized language (i.e., “murder hornet”) there are plenty of negative impacts. Photo credit: PJ Liesch, UW Insect Diagnostic Lab.

I had plenty of reports of social wasps (yellowjackets, bald-faced hornets, and paper wasps) as well as bumble bees this year—including three reports of the endangered rusty-patched bumble bee in the same week in early August! We missed the Brood X “cicada craze” here in Wisconsin, but I still had plenty of questions about them from reporters. We will, however, see some periodical cicadas (Brood XIII) in 2024 in southern Wisconsin.

Some other IDL case highlights from 2021 include:
-An explosion of hackberry emperor butterflies in late spring in south central Wisconsin
-More black witch moths than I’ve ever seen before in a single year (over a dozen sightings!)
-First specimens of the invasive Asiatic garden beetle collected in Wisconsin
-An influx of fall armyworms in late summer, and finally
-Unexpected (live) European insect imported in a Jeep

Every year is a bit different here at the UW Insect Diagnostic Lab and 2021 was no exception.  I’ll be curious to see what 2022 has in store for insects in Wisconsin!

—PJ Liesch
Director of the University of Wisconsin Insect Diagnostic Lab

Beetles, Crop Pests, Invasive Species, Ornamental Pest

Asiatic Garden Beetles Collected in Wisconsin for the First Time

Serendipity can play a big role in being an entomologist or any kind of naturalist. Sometimes, you’re simply in the right spot at the right time to make an interesting observation or scientific discovery. There’s lots to learn about the natural world around us and plenty of room for discoveries.

Think about birds for a moment. According to the Wisconsin Society for Ornithology, there are 441 species of birds known from the state. Birders can spend an entire lifetime learning about the biology and habits of these species and how to identify them by sight, song, and other features. Now, think about insects. Here in Wisconsin, our best estimate is that we have somewhere in the ballpark of 20,000 insect species in the state (let alone all the other arthropods!). During talks to the public, I often joke that birders have it easy—with so many insects out there, you could have ten lifetimes and still have plenty to learn and discover!

With that said, there’s lots to be discovered in the world of insects. Even though I’ve been collecting and studying these creatures for over 15 years, I still make discoveries on a regular basis. This often requires hours of diligent observations and the ability to focus on the tiniest of details, but in other cases it comes down to plain old luck. For example, I’ve written about discovering and collecting specimens of the rare fly, Asteia baeta, in my house after setting up a Christmas tree (no such luck this year…).

Photo of adult Asiatic garden beetles
Asiatic garden beetle adults. Photo credit: Emmy Engasser, Wichita State University, Bugwood.org.

A more recent example of entomological serendipity occurred this last July in my own backyard in Dane County. I was enjoying a cold beer on our back deck one warm evening  when I noticed a few small scarab beetles on our window screens. Since I keep a lookout for invasive species as part of my job at the UW Insect Diagnostic Lab, I always have a list of species in mind that I’m keeping an eye out for. In this particular case, the beetles piqued my interest due to their resemblance to the non-native Asiatic garden beetle (Maladera formosae), although we have native species in the genus Serica that can look similar to the naked eye. Just a few weeks before this, I had identified some specimens of the Asiatic garden beetle from a suburb of Chicago, which placed the species on my immediate radar.

Hold my beer, I’m getting some vials. I collected all the specimens I could spot (4), and was able to confirm their identity as the Asiatic garden beetle after tracking down appropriate keys and dissecting out the male genitalia—a surprisingly common and delicate entomological task used to distinguish certain insects that look similar. While I’ve seen a possible report of the AGB on iNaturalist, the specimens from my back deck marked the first specimens of the Asiatic garden beetle collected and confirmed from the state of Wisconsin.

Adult Asiatic garden beetles colleted in Wisconsin.
A few of the Asiatic garden beetle specimens known from Wisconsin. Photo credit: PJ Liesch, UW Insect Diagnostic Lab.

The Asiatic garden beetle first showed up in the United States in New Jersey in the early 1900’s and has spread westward ever since. This species is a notable pest and feeds on a wide range of plants. The adult beetles are “sneaky”—hiding by day and causing most of their damage after dark. They are primarily active on warm evenings (>70˚F) and can be strongly attracted to lights. In this case, not only was I enjoying a cold beer on a warm summer night, but the string of patio lights over our deck likely attracted the beetles from the nearby area. The larvae (white grubs) can be pests of turfgrass, home gardens, and agricultural crops such as corn and potatoes.

Adult Asiatic garden beetle and plant damage.
An adult Asiatic garden beetle and feeding damage on a landscape plant. Photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org.

At this point, I have many more questions than answers about the Asiatic garden beetle and what the future holds for this species in Wisconsin. To date, only a handful of specimens have been collected (four in July and another specimen in mid-September) and no plant damage has been observed. However, I’ll be keeping a close eye on this species, since reports from nearby states suggest that we may be seeing more of this species and damage in the coming years.

Bugs, IDL Highlights, Odd Insects, Uncommon Insects

Jeep ‘Adventure’ Leads to an Unexpected Insect Discovery in Wisconsin

On average, I see 2 – 3 new, non-native insect species show up in Wisconsin every year through my work at the UW Insect Diagnostic Lab (3 so far in 2021!). I’ve mentioned this in previous blog posts, but humans make excellent accomplices in moving species from one spot to another on the globe. This last spring, I saw one of the most interesting cases of my career which highlights this point exactly.

Like any good globetrotting adventure, this story involved a rugged, adventurous mode of travel—a Jeep. This particular Jeep had been imported in late 2020 and after a period of time in the eastern US, it eventually wound up in a small town in central Wisconsin. Unbeknownst to the owner of the vehicle, this Jeep also contained unexpected insect stowaways.

These insects managed to survive for months sheltered within the Jeep and would become active when the vehicle was in use—unexpectedly wandering out of nooks and crannies, much to the displeasure of the driver. Obviously, this isn’t something a new car owner wants to see, so a pest control professional was consulted about the insects and they got in touch with me at the UW Insect Diagnostic Lab to figure out what the specimens were. In the initial conversation, the mystery insects had been described as “stink bugs” and I figured that overwintering nuisance insects like the brown marmorated stink bug might have been involved. The photos, however, hinted at something far more puzzling.

The initial photo I received of the mystery insect on a car window.  Limited resolution, but definitely not a stink bug or anything else that I recognized. This certainly was a “we’re not in Kansas anymore” type moment.

By this point, I had been running the UW Insect Diagnostic Lab for six years and hadn’t seen anything quite like the insect in the photo. I requested a sample to get to the bottom of this mystery under the microscope.  I handle so many cases at the diagnostic lab (~2,500 annually), that I can generally identify most specimens to family (or perhaps even genus or species-level) with a quick peek. In this case I was utterly perplexed, meaning I had to run it through a general family-level taxonomic key for the true bugs (Order Hemiptera). In Borror and DeLong’s Introduction to the Study of Insects the specimens keyed out to the Family Heterograstridae.

From the Hemiptera family key from Borror and DeLong’s Introduction to the Study of Insects. The asterisk symbol (*) is always a surprise.

An asterisk is always a surprise when you encounter it in a taxonomic key. It generally means one of two things: you either took a “wrong turn” in the decision-making process (and misidentified the specimen) or it’s something rare or highly unusual. Something seemed amiss, so I consulted a few other keys to further confirm the Family Heterogastridae. In North America there’s only a single genus (Heterogaster) from this family and three species known from the west coast of the US. The specimens in my possession looked markedly different. Because the Family Heterogastridae is mostly a footnote in the western hemisphere, it’s hard to find information on this group of insects.

This is why geographic clues can be so important in diagnostics and why I request this information with every sample at the UW Insect Diagnostic Lab. Knowing where a specimen was collected and/or originated helps tremendously in learning more about it. Through follow-up conversations, I learned that the Jeep was manufactured in and imported from Melfi, Italy—meaning there was a good chance I was looking in the completely wrong hemisphere for the information needed to identify it.

This led to many evenings of armchair sleuthing. During this process, I’d like to imagine myself as Jason Bourne tracking down members of an international conspiracy while a suspenseful soundtrack blared in the background, but in reality I was mostly just locating pdfs of scientific papers and using Google Translate. Such work could have taken months or even years a few decades ago, but was now possible in the matter of a week or two.

Thanks to Interlibrary Loan and other online resources, I tracked down manuscripts from a half-dozen European and Middle Eastern countries in multiple languages and spent hours pouring over posts on Italian and French insect forums looking for clues. I finally found my answer in a scanned pdf version of Jean Péricart’s Hémiptères Lygaeidae euro-méditerranéens, vol. 1., which identified the specimens as Platyplax inermis—a species associated with Salvia spp. plants in the Mediterranean region.

Map showing reports of Platyplax inermis from its native range. Map credit: iNaturalist.

Having finally identified the stowaway insects and their origin, my work was mostly done at that point. The species happened to be on the USDA-APHIS regulated plant pest list (technically, the entire family Heterogastridae is listed), so I reached out to colleagues at the USDA-APHIS office in Madison to hand off the case. Specimens were sent off to an APHIS field office in Chicago and then off to the Smithsonian for further confirmation, a few specimens are also being deposited in the Wisconsin Insect Research Collection.

While most cases at the UW Insect Diagnostic Lab aren’t anywhere near this exciting, even insect diagnosticians get to live vicariously every once in a while.

 

Caterpillars, Crop Pests, In the News, Moths

Fall Armyworms: A Late Summer Surprise in Wisconsin

It’s been hard to miss the recent news headlines about fall armyworms “FAW” (Spodoptera frugiperda). States east of the Rockies have seen historical outbreaks of this insect in 2021, including a bit of fall armyworm activity here in Wisconsin. In some cases, the caterpillars have decimated entire crop fields or home lawns overnight before marching onwards in search of “greener pastures”.

We usually don’t see much of the fall armyworm in Wisconsin and it’s primarily a pest of warmer areas, such as the gulf coast states.  The FAW is native to tropical and subtropical parts of the western hemisphere and the larvae (caterpillars) can feed on dozens of different types of plants—ranging from field crops to fruits and vegetables and even turfgrass. They can be particularly important pests to crops such as corn, grains, and alfalfa.

Fall armyworm caterpillar
Fall armyworm caterpillar. Photo credit: Frank Peairs, Colorado State University, Bugwood.org.

The fall armyworm can’t survive the winters in the US, other than the southernmost areas (e.g., southern Texas and Florida). However, in spring and summer the adult moths migrate northwards and lay eggs. Over the course of many generations and subsequent northward migration, fall armyworms can make it to the upper Midwest and even parts of southern Canada. Historically, fall armyworm has rarely been a notable pest in Wisconsin or the upper Midwest—it simply arrives too late or in too small of numbers to be a concern. To a certain extent, every year is a roll of the dice, but the odds are usually in our favor in Wisconsin and other northern states.

Fall armyworm adult moth
Fall armyworm adult moth. Photo credit: Lyle Buss, University of Florida, Bugwood.org.

This year has been different though, with large numbers being spotted northwards and reports of significant damage coming in from nearby states such as Illinois, Indiana, Iowa, and Ohio. Many other states ranging from Kansas to the mid-Atlantic region have also been impacted in the later parts of summer. While there have been scattered reports of fall armyworm damage to field crops in southern parts of Wisconsin, the lateness of this pest’s arrival and our declining temperatures have likely spared us from the widespread damage seen in other states.

Under hot conditions (e.g. temps in the 90’s), the life cycle of the fall armyworm—from eggs to adult moths—can take only a few weeks. However, fall armyworms are “cold blooded” creatures and cooler temperatures slow down their growth and development. Depending on how chilly it is, their life cycle can be “stretched out” to take 60 days or longer—leaving them much more vulnerable to predation, parasitism, or exposure to frosts.

Eggs of the fall armyworm
Fall armyworm eggs from a residential yard. Photo submitted to UW Insect Diagnostic Lab in September, 2021.

One study* found that fall armyworm eggs didn’t hatch at all if temperatures were cool enough (though not particularly chilly by Wisconsin standards). That particular study simulated daytime/nighttime temperatures of 21˚C (70˚F) and 8˚C (46˚F)—temperatures that are “in the ballpark” for many parts of Wisconsin by mid-September and are often considered downright “pleasant” by Wisconsinites.  Eggs held at warmer temperatures in the experiment hatched just fine.

For eggs that did hatch this year in Wisconsin, cool temperatures also could have helped us out by slowing down their development. As they grow, fall armyworms pass through six sub-stages (instars). The early instar caterpillars are so small, they simply can’t eat much and cause little damage. It’s not until FAW caterpillars become more mature fifth and sixth instars that they really start to chow down and cause significant damage to plants. Thus, falling temps could help prevent the fall armyworm caterpillars from making it to the destructive late instar stages and could also leave them more exposed to a variety of threats.

Chart showing quantity eaten by fall armyworm larval instars.
Graphic representation of the amount eaten by fall armyworm caterpillars in an early USDA experiment. Early instar caterpillars eat little compared to late instars. Cool temperatures limiting their development could help prevent damage by the FAW. Credit: USDA Technical Bulletin No. 34

The fall armyworm outbreak of 2021 could very well be a “once every few decades” type of event, and our northern location likely helped us avoid the significant problems seen in other states. However, if changing climate gives the fall armyworm a “head start” by overwintering farther north, it’s possible that we could see more of this pest in Wisconsin in the future.

*Barfield, Mitchell, and Poe. 1987. A Temperature-Dependent Model for Fall Armyworm Development.  Annals of the Entomological Society of America. 71(1): 70-74.

Crop Pests, In the News, Invasive Species, Ornamental Pest

Spotted Lanternfly: The Next Big Pest in Wisconsin?

Is the invasive spotted lanternfly (Lycorma delicatula) poised to be a problem in Wisconsin? Only time will tell, but the threat is definitely real.

Spotted lanternfly adult
Adult spotted lanternfly. Photo credit: Emelie Swackhamer, Penn State University, Bugwood.org

What is the spotted lanternfly?
If you haven’t heard of the spotted lanternfly (SLF) before, it may be because this insect hasn’t been spotted in the upper Midwest yet. This invasive planthopper is native southeast Asia and was first spotted in the US (eastern Pennsylvania) in 2014. It has since spread to nearby states in the eastern part of the country. This plant-feeding pest poses significant concerns for both agricultural producers and the general public.

What do spotted lanternflies look like?
Spotted lanternfly adults and juveniles have a unique appearance and can easily be distinguished from our native insects. Adults are roughly 1 inch long with grey and black spotted forewings and bright pink patches on the hindwings; their abdomen is black and yellow. Although they have wings, adults are generally weak fliers and tend to walk or hop. The wingless juveniles (nymphs) are smaller than adults and are mostly black with white spots. When nearly mature, juveniles are red and black with white spots.

In contrast to the conspicuous adults and juveniles, the eggs have a subdued appearance. The small, brownish, seed-like eggs are laid in batches of 30-50 and are covered with a grayish putty-like material. These egg masses can resemble dried mud.

 

What is the life cycle of the spotted lanternfly?
The spotted lanternfly has one generation per year. In late summer, SLF females deposit egg masses containing 30-50 seed-like eggs on trees or other objects. After making it through the winter, the eggs hatch in late spring and juveniles emerge. Juveniles can’t fly, but can walk or hop on plants. The juveniles feed and grow over the course of two months before transforming to adults in mid-summer. Adults are present into the fall as they feed, mate, and lay eggs.

What do spotted lanternflies feed on?
Spotted lanternfies are plant feeders. Their preferred host plant is the invasive tree-of-heaven (Ailanthus altissima), which occurs in its native range in China. However, this pest is known to feed on over 100 different plants. Certain agricultural crops can be attacked, including: hops, pome fruit (apples, pears, etc.), stone fruit (peaches, plums, cherries, etc.), nut trees, grapes, and others. The spotted lanternfly can also feed on a wide range of landscape and forest trees and shrubs which can pose concerns for plant nurseries, homeowners, landscapers, and tree care professionals. Tree and shrub species known to be attacked include: maples, oaks, hickories, walnuts, cherries, catalpa, willows, serviceberry, roses, lilacs, and many others. Spotted lanternflies can feed gregariously and hundreds or thousands of individuals are sometimes spotted on tree trunks or branches.

What type of damage to they cause?
When SLFs feed, they use needle-like mouthparts to pierce plant structures to drink sap. Not only does this wound plants and create potential entry points for disease pathogens, but wounds may continue to ooze for some time—creating an unsightly mess. Significant feeding could cause dieback of branches of trees or shrubs and reduce yields of agricultural crops. The presence of SLF adults at the time of harvest could also pose a potential contamination concern for certain crops. In addition, spotted lanternflies excrete honeydew (undigested sugars) in their waste, which can lead to the growth of black sooty mold on the trunk or base of trees.

Aggregation of spotted lanternfly adults and damage at base of tree
Aggregation of spotted lanternfly adults, oozing feeding wounds, and growth of black sooty mold at base of a tree. Photo credit: Emelie Swackhamer, Penn State University, Bugwood.org

What’s the invasion risk from spotted lanternfly?
There’s significant concern about the spread of the spotted lanternfly. Since the first detection in Pennsylvania in 2014, this insect has already spread to many other states in the eastern US. Overall, spotted lanternflies mostly walk or hop (adults are weak fliers), but they are good at “hitchhiking” which may contribute to their spread; eggs are of particular concern. Egg masses are often laid on plant materials (e.g. tree trunks), but they can also be laid on man-made objects such as pallets, crates, automobiles, trailers, and other items. With their subtle appearance, egg masses can easily be overlooked and could be transported long distances. The movement of eggs could end up playing an important role in the spread of this insect over time.

A 2019 study evaluated potential spotted lanternfly habitat in the United States. The Midwest (including parts of Wisconsin) is expected to be good habitat for this invasive insect, highlighting the importance of early detection of this pest. If you suspect you’ve found the spotted lanternfly in Wisconsin: please take pictures, save any specimens you find, and contact me at the UW Insect Diagnostic Lab.

For additional information about the spotted lanternfly, check out these resources from the UW-Madison Division of Extension and the Wisconsin Department of Agriculture, Trade and Consumer Protection.

Outdoor Insect Invaders

The Summer of Springtails

With the unusually dry weather we’ve had in Wisconsin this year, I would not have predicted that springtails (Collembola), would have been one of the commonest samples at the UW Insect Diagnostic Lab this summer. In general, springtails tend to thrive under damp conditions. These tiny (<1/10 inch long), insect-like creatures are commonly associated with leaf litter, rich soil, compost, and mulch or plant beds outdoors where they feed on fungi and decaying plant materials.

Photograph of a springtail on a log.
A tiny springtail on a decaying log outdoors—a common place to spot these creatures. Photo credit: Melissa McMasters via Wikipedia.

Springtails are ubiquitous and can be found around the globe under a wide variety of conditions. In many parts of North America, you can even bump into large numbers of dark-colored springtails (snow fleas) bouncing around on the snow in winter.  Springtails are a fairly diverse group with over 15 Families in North America, so there’s a lot of variability in terms of the color and overall appearance.

Indoors, it’s usually too dry for springtails to survive or reproduce unless damp conditions exist. Occasionally, they can be found indoors in association with overwatered houseplants, new construction (due to residual moisture in construction materials), plumbing leaks, and other moisture issues. In many cases, when springtails are spotted indoors, they originated outside and simply snuck in but perish shortly thereafter due to desiccation.

Chart shwoing drought conditions in Wisconsin in June of 2021.
Drought conditions in Wisconsin—June of 2021. Much of the state experienced drier than usual conditions this year, with some parts experiencing extreme drought conditions. Photo credit: US Drought Monitor Program: https://droughtmonitor.unl.edu.

With the lack of precipitation and this year, I haven’t gotten the impression that springtails are necessarily thriving outdoors. However, the hot and dry conditions are likely forcing springtails to sneak into structures or other spots that may be slightly damper, darker, and cooler. When they do make it inside, springtails are often spotted near moisture sources—kitchen or bathroom sinks, showers or bathtub drains, and basement floor drains. Some good news is that springtails are completely harmless to humans, pets and homes, and in most cases won’t survive long.

Hundreds of springtails along a home's foundations.
Hundreds of springtails along a home’s foundation. Photo submitted for a recent case at the diagnostic lab.

The following tips can be helpful when springtails are a problem indoors:

  • Monitor both indoors and outdoors—Visually inspect for areas with lots of springtails and see if potential entrance points into structures are nearby. Indoors, glue board traps from the hardware store or garden center can be helpful tools for monitoring and management.
  • Manage vegetation near the foundation of homes and other structures—Plants near a foundation can hold in moisture and create good habitat for springtails, spiders, millipedes, and insects that can wander indoors. Having a gap of 1-2 feet or more between a structure and plants increases airflow and can decrease humidity.
  • Avoid excessive mulch—A thick layer of mulch can hold in moisture and may create good habitat for springtails and other arthropods.
  • Physical exclusion—Sealing up potential entrance points into a structure can help with many pests, including springtails. Caulk and expanding insulation foam can be helpful in this regard. Inspect and replace weather stripping to make sure that windows and doors seal properly. Pay particular attention to high priority areas such as along the foundation, around window and door frames, and basement window wells.
  • Keep indoor humidity low—Running a dehumidifier and/or air conditioning can help decrease moisture and make it harder for springtails to survive. Repair or correct any drainage, plumbing, or moisture issues that may be increasing humidity levels within a structure. Allow houseplants to dry out between waterings; soil that is kept damp can be a potential hangout for springtails indoors.
  • Insecticides—Since springtails sneaking in from outside don’t survive long, spraying indoors is generally not warranted or helpful. If springtails are highly problematic, treating cracks and crevices on the exterior of a structure may decrease the number making it inside but won’t eliminate them outright.