Tag Archives: 2021 Lab Highlights

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

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.

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.

 

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.

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.

Hackberry Emperor Butterflies Take the Stage in Wisconsin

Wisconsin is home to roughly 150 species of butterflies. Some of these, like monarchs (Danaus plexippus), are well-known and easily recognizable. Other species can be more subtle in appearance (such as the “skippers”) or may not be particularly abundant. Nonetheless, we occasionally see localized “booms” of certain butterfly species from time to time. This year, the hackberry emperor butterfly (Asterocampa celtis) has taken the stage in some parts of the state.

Hackberry emperor butterfly with wings spread
Hackberry emperor butterfly. Photo credit, Richard Crook via Flickr.

In the last month, I’ve had more reports of hackberry emperor butterflies at the UW Insect Diagnostic Lab than any other butterfly species. These reports have primarily come in from southcentral and southwestern Wisconsin. In some cases, hackberry emperors have been spotted by the thousands as they covered rural roads or transformed backyards into temporary live butterfly exhibits.  Hackberry emperors primarily occur in southern parts of the state where the food plant of the caterpillars (hackberry trees) can be abundant; they’re also known from parts of central and west central Wisconsin.

Hackberry emperors are mid-to-large sized butterflies with a wingspan of approximately 2 inches. Their brownish-orange and black wings are somewhat similar to certain other butterflies (such as the “Satyrs”), which can make identifying them a bit more challenging to the uninitiated. Luckily, there’s a distinctive row of black spots on the wings—one distinctive spot on the topside of each forewing and seven slightly smaller spots on each hindwing. When the undersides of the wings are viewed (such as when the wings are folded upwards at rest), these black spots are bordered with a bit of yellow, giving them an “eyespot” appearance.  A close relative and look-alike, the tawny emperor (Asterocampa clyton), lacks the large black spot on each forewing.

Hackberry emperor butterfly with wings folded at rest
Hackberry emperor butterfly lapping salt. Photo Credit: Judy Gallagher via Wikipedia.

Adults butterflies often serve as pollinators when they visit flowers for nectar, but hackberry emperors have slightly different behaviors.  They prefer to head to oozing tree wounds for sap or decaying plant materials in compost piles. They’re also fond of salts and can readily be spotted at puddles (a phenomenon simply known as “puddling”), at dung or carrion, lapping sweat from humans, or on roadways.

Hackberry emperor butterflies on a rural road
Thousands of hackberry emperor butterflies were recently spotted on roadways in southwestern Wisconsin. Photo Credit: Jay Watson, WI-DNR. [Photo used with permission]
After overwintering as partially-grown caterpillars, hackberry emperors complete their development in late spring with two broods (batches of adults) in southern Wisconsin.  We see the first batch of adults in June, with the other in August, so we may see more of this species later this summer. If you’re located in southern Wisconsin, keep an eye out for these abundant butterflies in 2021.

In Defense of Ground Bees

“Ground bee” season is officially here, but before we get any further, let’s clear up a few things about these insects.  Ground-nesting bees get a lot of undeserved blame for stings that they simply aren’t responsible for.  Despite their claims, many folks have probably never been stung by an actual “ground bee”.  Every year I get plenty of calls about “angry stinging ground bees” in late summer, but these are almost always ground-nesting yellowjackets (Vespula spp.).  Undoubtedly, if you stumble into an in-ground yellowjacket nest, you’ll be forced to make a hasty retreat from the area as the colony defends itself.  But those aren’t bees

Entrance of a ground-nesting yellowjacket nest in late summer. These might be black and yellow, but they aren’t bees… Photo credit: Jeff Hahn, U. Minnesota.

While yellowjackets and bees are related (both belong to the insect order Hymenoptera along with the ants and sawflies), they belong to completely different families.  From a standpoint of taxonomic classification,  mixing up yellowjackets and bees would be like confusing dogs for cats, raccoons, or walruses (all belong to separate families within the mammalian order Carnivora).  We do technically have social, ground-nesting bees that can be ornery if disturbed (i.e., bumble bees), but folks generally recognize bumble bees by their large size and robust appearance.  

A solitary ground nesting bee guarding the entrance to its nest in a city park in Middleton, WI. Photo credit: PJ Liesch, UW Entomology.

So what about these other “ground bees”?  Most bees (about 2/3 of all bees) are actually ground-nesting species.  In the Midwest, we’ve got around 500 different bee species, meaning there are hundreds of ground-nesting species around us.  Our common ground-nesting bees include species of: cellophane bees, mining bees, squash bees, longhorned bees, sweat bees, and others. For the most part, these ground-nesting bees are solitary creatures that live alone, although many nests can occur in the same general area as shown in the video clip below.  They often prefer sunny, open areas with thin ground cover or bare, sandy soil and can be common in parks and home lawns.  

To a certain extent, solitary bees can be thought of as the insect equivalent of “preppers”.  Each bee digs her own nest—a small, bunker-like tunnel in the ground, which looks like an ant hill.  Not only do the females have to construct these shelters, but she has to gather all of the provisions needed for her young to survive inside—often in the matter of just a few weeks.  The female bees collect pollen and nectar from flowers to create a nutritious substance called bee bread, which they place into small chambers (cells) and lay an egg.  Once the eggs hatch, the young bees (larvae) have all the supplies they’ll need to grow and develop in their survival bunkers.  

Most of these ground bees have a single generation per year.  The adult bees are out and active for a short period of time (often a few weeks), before they’re done and gone for the year.  When they are active, our solitary bees can be excellent pollinators and can be more efficient than honey bees in some regards.  However, their pollination services often go unrecognized and unappreciated by the general public.  While news articles regularly sound the alarm about honey bee declines, we should really be much more concerned about the potential loss of our solitary bee species, as they’re more sensitive to disturbances, pesticides, and other stressors.

Post-jog entomologist next to five solitary bee nests. These bees are extremely gentle and unlikely to sting. This portion of a local park had thousands of solitary bees flying around. Photo credit: PJ Liesch, UW Entomology.

If you spot ground bees this time of the year, is there any reason for concern? No. Solitary ground-nesting bees are great to have around.  Being solitary nesters, these ground bees don’t have a large colony of  adult relatives to defend and they end up being surprisingly gentle and unlikely to sting.  Overall, they pose little risk to people or pets.  The best thing to do is to simply let them be and appreciate the pollination services they provide. 

If you’d like to learn more about Wisconsin’s bees, check on the Wisconsin Bee Identification Guide or the US Forest Service’s Bee Basics: An Introduction to Our Native Bees. If you have solitary ground-nesting bees in your yard and would like to teach others about these amazing pollinators,  click the image below to get a  sign to laminate and post:

A yard sign about wild bees