The spectacular fall weather this week has made it hard to work indoors. As Midwesterners, we know to appreciate the current warm spell as winter is just around the corner. If you’re like me, you’ve probably made it outside to take care of yard work, hike, grill out, or simply enjoy the fall colors. Speaking of colors, you’ve probably notices flashes of orange on the side of your home—multicolored Asian lady beetles (Harmonia axyridis). This fall, we’re seeing surprisingly high numbers of these lady beetles across Wisconsin.
Just like us, the final warm days of autumn have worked these lady beetles into a frenzy of outdoor activity and our recent weather patterns are the key to this phenomenon. While not native to North America, the Asian lady beetle is an adaptable species and has a good feel for the seasons—it also knows that winter is coming. An important cue for lady beetle activity is the first frost or period of near-freezing temperatures in fall. This sets the stage and when the temperatures creep back up into the mid-60’s or 70’s, it initiates a massive game of hide-and-seek-shelter for these insects.
But why our homes? It turns out that Asian lady beetles don’t necessarily want to invade our homes—they simply look for sheltered spots to spend the winter. In more natural settings, I’ve found dozens of these beetles beneath the loose bark of dead trees or in firewood piles during the winter months.
In their native range of eastern Asia, multicolored Asian lady beetles are cliff dwellers. These beetles use visual cues to actively seek out conspicuous, exposed rock faces with cracks to squeeze into. They’re particularly fond of south or west facing cliffs, which get warmed by the sun in the afternoon when they’re most active. The lady beetles fly to these rock outcrops and examine the cracks and crevices to see if a suitable overwintering site has been found. To us, our homes don’t necessarily resemble cliffs, but to the Asian lady beetles, the basic formula is there: large contrasting objects that stand out in the landscape with an abundance of vertical and horizontal lines resulting from modern design and construction methods. To the beetles, this looks close enough that they’ll fly to structures and wander around seeking out nooks and crannies to slip into as shown in the video clip below from the UW-Madison campus.
From the lady beetle’s point of view, these insects would really prefer to slip into a sheltered crack or crevice, hunker down for the winter, and leave again in the spring. However, when these insects get beneath siding or into a soffit area of our homes, they can accidentally pop out in the living quarters of the home—much to the dismay of the human inhabitants. This isn’t ideal for the insects either, which can face death by desiccation in the dry winter air indoors.
Enjoy these final warm days of autumn, because we’ll all be bundled up inside soon enough—with or without a bunch of lady beetles.
My final two cents: One of the best, long-term approaches to prevent nuisance issues with multicolored Asian lady beetles and other insects (like boxelder bugs and brown marmorated stink bugs) is to have good physical exclusion. This refers to making sure that potential entrance points on structures are sealed up due to good construction methods, caulk, expanding insulation foam, weatherstripping, or similar means.
Given their small general size, multicolored Asian lady beetles can squeeze through cracks or gaps as small as ⅛ inch in size. For perspective, this is about the same height as two pennies stacked atop one another. With that said, if you can easily slide two stacked pennies into a crack or crevice on the side of your house—it’s a big enough opening for multicolored Asian lady beetles to potentially get in!
The largest moths you’ll likely encounter in the northern United States are the giant silk moths (Family Saturniidae). We have a handful of species in the Upper Midwest which can be encountered with some regularity during the summer months: cecropia moths, polyphemus moths, luna moths, promethea moths, and imperial moths. True to their name, the giant silk moths don’t skimp on size—they generally have wingspans in the range of 3 – 6 inches, depending on the species. These moths are native to our area and the impressively large caterpillars feed on the leaves of various hardwood trees.
Finding an adult giant silk moth or one of the caterpillars is always a special occasion. However, there’s an even more impressive large moth, which occasionally pops up in our area—the Black Witch (Ascalapha odorata). The black witch has a wingspan of around 6 inches and can often be mistaken for a bat due to its dark colour. This tropical species doesn’t natively occur in our area and originates in parts of South America and Central America. However, the adult moths are somewhat regular “strays” and find their way as far north as parts of Canada. Still, black witches aren’t common in Wisconsin (or the US in general), and I typically only hear of a few reports in the state each year.
Wind plays an important role in the movement of black witches from their native habitat. One report even documented an adult black witch traveling with a strong westerly wind to an island in the south Atlantic—a distance of over 2,000 miles from South America. In the upper Midwest, dips in the jet stream and storm systems can play an important role. Since starting at the UW Insect Diagnostic Lab in 2014, I’ve seen several cases where black witches are spotted in late summer after hurricanes have hit the Gulf Coast states. Along these lines, hundreds of black witch moths arrived in Texas as Hurricane Claudette passed through in 2003. Following such an intense journey, the moths are often damaged, with tattered wings or other injuries. Surprisingly, some moths seem to arrive in nearly pristine condition, like this beautiful specimen spotted in Door County last month shortly after hurricane Sally made landfall.
If you do ever spot a black witch, consider yourself lucky. If you’re extremely lucky, you might even spot one of the rarest moths that strays to the Midwest—the “owl moth” (Thysania zenobia)—another large moth which has only ever been spotted in Wisconsin a few times and is much rarer than the elusive black witch.
With the media craze about “murder hornets” this past spring, I’ve seen a definite increase in reports of Asian giant hornet look-alikes at the UW Insect Diagnostic Lab this summer. Many folks recognize the commonest look-alike in the Midwest, the eastern cicada killer (Sphecius speciosus), which becomes active in July around the time that their prey (cicadas) start emerging. Another look-alike is one that you might not have bumped into before—the great golden digger wasp (Sphex ichneumoneus). Similar to Asian giant hornets, great golden digger wasps are large and nest in the ground, which are reasons why they may be mistaken for the former.
If you haven’t spotted one before, great golden digger wasps can be a bit intimidating in appearance as they can easily be over an inch long. However, their anatomy and appearance are quite different compared to Asian giant hornets. Great golden digger wasps are mostly black with a rusty-reddish color at the base of the gaster (“abdomen”). Their legs are the same reddish color and the black thorax and head possess fine golden setae or “hairs” (hence “golden” in their name). In contrast, Asian giant hornets have distinctive black and yellow stripes on their gaster and a vibrant yellowish-orange head. Great golden digger wasps belong to the “thread-waisted” wasp family (Family Sphecidae) and have a long, slender petiole (“waist”). This isn’t as thin and narrow as the “waist” of the related black and yellow mud dauber (Sceliphron caementarium), but still is quite noticeable when viewed from the side.
In terms of their biology, both Asian giant hornets and great golden digger wasps do nest in the ground, but the similarities end there. The Asian giant hornet is really quite similar to our ground-nesting yellowjackets in terms of their nesting behavior. These are social creatures which start nests from scratch in spring and build up in size over the course of the warmer months. Colonies ultimately die out in fall except for the “new” queens which overwinter. With a large colony of relatives to defend, social wasps can be defensive, especially when colonies are at peak size.
In contrast, great golden digger wasps are solitary ground nesters. Without a large colony of relatives to defend, they’re usually non-aggressive and very unlikely to sting. Stings are only likely if one were to pick one up bare-handed—in which case you might be asking for it! Similar to cicada killer wasps, each female great golden digger wasps excavates small tunnels in sandy soil and provisions them with prey for their young to feed on. In the case of the great golden digger wasp, prey consists of katydids, crickets, and relatives from the “grasshopper” group (Order Orthoptera). Rather than kill outright, the females inject their prey with a paralytic “cocktail” to keep them alive and fresh for their young to feed on—what a way to go! In addition to hunting katydids, adult great golden digger wasps visit flowers and can be beneficial pollinators.
Because they’re unlikely to sting humans, controlling great golden digger wasps is rarely justified and these magnificent creatures can simply be admired. Ultimately, these wasps are strongly associated with sandy soil, so if you see them in your yard every year and would prefer to not have them around, modifying the landscaping may be a long-term option to dissuade them from an area.
Author’s note: As of August 2020, Asian giant hornets have not been found in Wisconsin or anywhere in the Midwest. In North America, these insects are only known from far northwestern Washington state and nearby parts of British Columbia.
See this earlier post for additional details on the Asian giant hornet.
In the grand scheme of things, most insects (and spiders) are loners. Perhaps they set a good example for us in 2020 with their social distancing.
Of course, insects have to find a mate to reproduce at some point in their lives*, but out of the 1 million+ described insect species, being truly “social” isn’t the norm. There certainly are some well-known examples of insects that are eusocial—i.e., they live together as a colony. Examples include ants, certain types of wasps (such as yellowjackets and paper wasps), some bees, termites, and a few other interesting examples. However, there are many insects that are much more solitary in their habits. If you think of our bees in the Great Lakes region, we have roughly 500 species. Other than honey bees, bumble bees and a few others, the vast majority of these species are solitary creatures with each female doing her own thing.
Interestingly, there’s a quirky insect that can be commonly encountered this time of the year and it missed the memo on social distancing. I’m referring to an interesting species of barklouse (Order Psocodea): Cerastipsocus venosus. Barklice are relatives of true lice (e.g., head lice and pubic lice) but they’re really quite harmless to humans and tend to be scavengers. Barklice make up an obscure group of insects and many entomology students simply identify them to “order” level as this group can be challenging to narrow down further to family, genus, or species.
If you haven’t encountered Cerastipsocus venosus (aka “tree cattle”) before, it might catch you off guard to find a group (formally known as a “herd”) of these small insects hanging out together on the bark of a tree or a rock in your yard. The tiny juveniles are particularly striking with yellow stripes on their abdomens. The adults are larger (up to 1/4″ long) and possess black wings.
Rest assured, these barklice pose no threat to trees or other plants in our yard and these native insects simply nibble on lichens, and pieces of dead tree bark. Every year I get many reports of these insects in mid- and late- summer at the UW Insect Diagnostic Lab and there’s no need to spray or do anything about these if you spot them in your yard. These barklice don’t seem to stay in the same place for very long, so perhaps their herds just move along looking for greener pastures.
*Some insects are able to reproduce asexually, and don’t technically have to find a mate…
Perhaps you’ve heard some buzz about periodical cicadas (Magicicada spp.) lately. These insects resemble our typical “dog day” cicadas, which we see in mid-to-late summer in Wisconsin, but they are orange and black with vibrant reddish eyes instead of a dull greenish color. Parts of the US are currently seeing mass emergences of periodical cicadas, which appear by the millions every 13 or 17 years depending on the species. I’ve had a number of questions this last month asking if this was “the year” for us to see them in Wisconsin, but it’s not time for the big show…yet.
Periodical cicadas are sorted into cohorts known as “broods”, which occur in particular geographic areas and emerge at specific points in time. For the most part, these insects are excellent timekeepers and some broods have been documented as far back as the 1600’s in the eastern US. There are entire websites and apps dedicated to these insects and their schedules, and scientists have labelled broods with Roman numerals to help differentiate the cohorts.
With all the broods out there, some parts of the US do see these cohorts overlap in space, but these can be separated by the years in which they emerge. In Wisconsin, the situation is fairly straightforward as we only see a single brood: Brood XIII. Brood XIII’s 17-year cicadas last emerged in 2007, meaning that we’ve got four more years to wait until their mass emergence in 2024.
Interestingly, I’ve received a number of photos and reports of periodical cicadas in Wisconsin over the last month or so. I’ve had several confirmed reports from the Lake Geneva area (Walworth County) a confirmed report from southeastern Dane County, and a suspected report from Sauk County. While most periodical cicadas stick to the schedule, occasionally some of these insects veer off course. These out-of-sync individuals are referred to as “stragglers” and it turns out that Brood XIII has a history of these stragglers. In the late 1960’s, large numbers of stragglers were documented in the Chicago area. Likewise, many of the Chicago suburbs are seeing a similar phenomenon this year. With that said, we did technically see some periodical cicadas this year, but we’ll have to wait a few more years before the real “fireworks”.
Asian giant hornets have hit the news recently, sometimes going by the name of “murder hornets”. Below are six key things to know about these insects and the situation in North America:
1) What is the Asian Giant Hornet?
The Asian giant hornet (Vespa mandarinia), which is also known as the “great sparrow bee” in its native range (or recently sensationalized as the “murder hornet”) is a wasp species native to parts of southern and eastern Asia. The Asian giant hornet is amongst the world’s largest wasps, with queens approaching a length of 2 inches (typically ~1.5 inches). Workers and males are smaller, but still measure over an inch long. Asian giant hornets have a distinctive appearance with a bright yellowish-orange head, a dark body, and alternating dark and yellowish stripes on the gaster (“abdomen”). This species creates subterranean nests, which commonly have a peak workforce of around 100 workers.
Asian giant hornets pose threats as an invasive species in North America. These insects are efficient predators with complex hunting behaviors. While Asian giant hornets prey upon a wide range of insects, they are capable of attacking honey bees. Under the right conditions, Asian giant hornets can decimate hives of European honey bees (Apis mellifera) within a few hours. Their potent stings can also pose medical concerns for humans.
2) What’s the risk in the Midwest?
Based on the current situation, the risk from Asian giant hornets in Wisconsin and the Midwestern US is extremely low. To date, Asian giant hornets have never been found in Wisconsin or surrounding states. A very small number of Asian giant hornets were spotted in southwestern British Columbia and northwestern Washington state in the second half of 2019. For Wisconsin, these sightings have been roughly 1,500 miles from us. At the time this article was written (early May 2020), Asian giant hornets had not been spotted in North America in 2020. Update 5/27: we recently learned that AGHs have made it through the winter in North America. This species recently resurfaced, as reported in the New York Times. Despite this recent finding, all confirmed sightings of the AGH are from the Pacific Northwest and these insects pose little risk for the Midwest at this time.
3) What’s the timeline of the Asian giant hornet story?
Asian giant hornets have gotten a lot of attention in the news recently, but these stories really missed the main “action”, which occurred roughly half a year ago. (Imagine if Sport Illustrated took half a year to write about the Super Bowl’s winning team!). The story of the Asian giant hornet in North America began in August of 2019 when a beekeeper in Nanaimo, British Columbia (SE Vancouver Island) spotted these wasps. Three specimens were collected at the time and their identity was confirmed.
Also in August of 2019, a beekeeper in Northern Bellingham, Washington (US) observed Asian giant hornets, but no specimens were collected. Back in Nanaimo, British Columbia, an Asian giant hornet nest was located and eradicated in an urban park (Robin’s Park) in September. A month later (late October, 2019) a specimen was photographed in nearby mainland British Columbia (White Rock, BC). Around that time, the same beekeeper in Northern Bellingham, Washington observed Asian giant hornets attacking a hive. The last sighting of the Asian giant hornet occurred near Blaine, Washington in December of 2019, when a dead specimen was collected and a live specimen was spotted at a hummingbird feeder.
Update June, 2020: Small numbers of AGHs have been reported in North America—but only in the pacific Northwest.
4) Have Asian giant hornets become established in North America?
The ability of the Asian giant hornet to survive and spread in North America is not understood at this time. In its native range, the Asian giant hornet is associated with forested and low mountainous areas with temperate or subtropical climates. A key unanswered question at the moment is: have the Asian giant hornets successfully overwintered in North America? Update 5/27: we recently learned that AGHs have made it through the winter. This species recently resurfaced, as reported in the New York Times.
Asian giant hornets overwinter as queens. If previously fertilized, queens attempt to establish nests during the spring months. Established nests won’t produce the next batch of queens to carry on their “blood lines” until mid-fall, meaning that responders monitoring the situation in the Pacific northwest will have roughly half a year to hunt down any nests. For this reason, 2020 will be a critical “make or break” year in the story of the Asian giant hornet in North America.
Responders in the Pacific Northwest have plans to monitor for Asian giant hornets with traps and visual methods. If spotted, individual hornets can potentially be tracked back to their nest to allow responders to eradicate the colonies. Full details of the USDA response plan can be viewed here.
5) Health risks to humans are low
By referring to the Asian giant hornet as “murder hornets”, recent news stories have given the false impression that these insects pose a regular threat to humans. Many stories have repeated the claim that Asian giant hornets kill around 50 people a year in Japan, where these hornets naturally occur. In reality, the actual numbers are much lower. Based on publicly available data from the Japanese e-Stat statistics portal, from 2009-2018 an average of 18 deaths were reported annually in Japan from hornets, wasps, and bees combined. For comparative purposes, roughly twice as many annual deaths (average of 35) were reported as the result of slipping and drowning in bathtubs over that same period of time.
Nonetheless, Asian giant hornets do have potent venom and 1/4 inch-long stingers, which pack a punch. Due to their large physical size, a relatively large volume of venom can be injected leading to painful stings. If many stings occur (such as if one were to disrupt a nest), medical attention is advised.
6) Are there any look-alikes?
While we don’t have Asian giant hornets in Wisconsin or the Midwest, we have plenty of other insects that are currently being mistaken for the Asian giant hornet or could be mistaken for these hornets later this year. Panicked individuals thinking they’ve found an Asian giant hornet might end up killing native, beneficial insects which pose little risk to humans—such as bumble bee queens, which are currently trying to establish their nests for the year.
Historically, the UW Insect Diagnostic Lab receives many suspected reports of Asian giant hornets every year—all of these have been misidentifications by the submitters.To date, no confirmed sightings of the Asian giant hornet have occurred in Wisconsin or the Midwestern US. However, with the media spotlight on the Asian giant hornet, an increase in false reports is expected at the UW Insect Diagnostic Lab this year. Click the diagram below to view a
Some of the commonest look-alikes include:
Cicada Killer Wasps (Sphecius speciosus) These are the closest match in terms of size. However, these solitary ground-nesting wasps are really quite harmless, unless you happen to be a cicada... Because these insects don’t have a colony to defend, they are very unlikely to sting. This is the top look-alike reported to the UW Insect Diagnostic Lab every year. For additional details see this post: Asian Giant Hornets—Nope!
Great Golden Digger Wasps (Sphex ichneumoneus) These solitary ground nesting wasps capture and feed katydids and related insects to their young. Because these insects don’t have a colony to defend, they tend to be docile.
Pigeon Horntails (Tremex columba) These primitive wasp-like insects develop inside of decaying trees as larvae and can be common. They are not capable of stinging, but females do possess a prominent egg-laying structure (ovipositor).
Elm Sawflies (Cimbex americana) These plump, wasp-like insects cannot sting. The caterpillar-like larvae can feed on elms, willows, birches, and other hardwood trees.
Bumble Bees (Bombus spp.) The Midwest is home to over 20 species of bumble bees. These beneficial pollinators play important roles in the ecosystem. Bumble bees do live together as colonies and can act defensively if the nest is directly disturbed, but these important pollinators are generally docile. Annual colonies reach maximum size in late summer and naturally die out in the fall.
Yellowjackets (Vespula spp. & Dolichovespula spp.) The Midwest is home to more than 10 species of yellowjackets. Common species, such as the German yellowjacket (Vespula germanica) are typically around ½ inch in length. Yellowjackets are social insects and depending on the species, nests can occur in the ground, in hollow voids (such as soffit overhangs or wall voids), or as exposed as papier-mâché type aerial nests. Annual colonies reach maximum size in late summer and die out naturally in the fall.
Bald-Faced Hornets (Dolichovespula maculata) Our largest social wasp in the Midwestern US, reaching lengths of approximately ¾ inch. Bald-faced hornets are technically a type of “yellowjacket” but have a distinctive black and white appearance. These insects create large papier-mâché type nests, which can approach the size of a basketball. Annual colonies reach maximum size in late summer and die out in the fall.
Does the COVID-19 situation have you cooped up at home? If so, you’re not alone during these unusual times. With the shift towards working from home, folks are spending more time in their own yards and gardens as well as nearby parks and nature trails. Spending time out in nature can have notable health benefits, but it also gives us a great opportunity to observe the creatures around us—including insects, such as butterflies.
In Wisconsin and the Upper Midwest, summer may be “peak” butterfly season, but a number of species can be active early in the year. These creatures might brighten your day during these tough times, and this guide will help you identify five of the commonest spring butterfly species in the Upper Midwest:
Mourning Cloak (Nymphalisantiopa):
This butterfly is often the first one seen in spring. It’s an easy species to identify given its large size (3-4 inch wingspan) and colors on the upper wing surface—dark wings bordered with a row of small blue spots and pale edges. Mourning cloaks overwinter as adult butterflies amongst leaf litter or in other sheltered spots, so as soon as it’s warm enough they can become active. This butterfly can catch people off guard if they fly while snow remains on the ground. In early spring when flowers haven’t bloomed yet, mourning cloak butterflies are fond of visiting the sap flows on trees caused by the activity of the yellow-bellied sapsucker.
Eastern Comma (Polygonia comma):
Like the mourning cloak, eastern commas overwinter as adult butterflies, so they’re ready to go as temperatures creep upwards. Eastern commas have a wingspan of approximately 2 inches. When spread, the wings are mostly orange with black spots and borders. The edges of the wings also have a “wavy” or “scalloped” appearance. The most distinguishing feature can be seen on the undersides of the wings when folded upwards: a small pale curved mark in the shape of a comma—hence the name. The closely-related question mark (Polygonia interrogationis) can also become active fairly early in the season and looks similar, but has a “?” shape on the underside of the hindwings.
Red Admiral (Vanessa atalanta):
The monarch butterfly (Danaus plexippus) is perhaps the best known migratory insect in our part of the world, but red admiral butterflies also migrate northwards in spring. The migratory behavior means that the arrival date and numbers can vary greatly from year to year, but red admirals can frequently be encountered in spring in the Upper Midwest. These butterflies have a wingspan of approximately 2 inches and have black wings with prominent white “!” marks near the tips of their forewings and a distinctive reddish-orange band cutting across the surface of their forewings.
Cabbage White (Pieris rapae):
Right around the start of the Civil War, the cabbage white made its first appearance in North America. Today, this European butterfly can be found widely distributed across much of the planet. Cabbage whites are indeed a whitish color with sooty black patches at the tips of their forewings. The forewings also possess black spots—1 spot for males, 2 for females. Their pale appearance and decent size (approximately 1 ¾ inch wingspan) make them easy to identify this time of the year.
Cabbage whites overwinter as chrysalises in the Upper Midwest, so they aren’t active quite as early as the mourning cloaks or eastern comma. However, the warmth of the sun can still lead to early spring sightings. Gardeners and vegetable farmers are well aware of this species since the caterpillars (“imported cabbageworms”) feed on plants from the mustard family—including broccoli, cabbage, and Brussels sprouts.
Spring Azure (Celastrina ladon ladon):
If you spot a cluster of small bluish butterflies around a puddle on a hiking trail in spring, there’s a good chance they’re spring azures. These butterflies are the smallest on this list, with a wingspan of only around 1 inch. The beautiful sky blue color of their wings can be seen in flight, but when they land, spring azures tend to keep their wings folded over their body, showing the grey undersides with an assortment of tiny black mark. There are many other species of small blue butterflies in our area throughout the year, but the spring azures are some of the earliest to fly and are wrapping things up for the year as June approaches.
The Upper Midwest is home to over 150 butterfly species—each unique in its appearance, biology, and distribution. If you’re looking for some additional resources to learn about our butterflies, some of my favorites include: Butterflies of the Northwoods by Larry Weber, A Swift Guide to Butterflies of North America by Jeffrey Glassberg, and the Wisconsin Butterflies website (wisconsinbutterflies.org) by photographer Mike Reese. The Wisconsin Butterflies website not only has wonderful photos and a wealth of information about each species, but users can view and submit butterfly sightings from around Wisconsin.
In the last month, COVID-19 has changed the ways that Americans go about their everyday lives. Here in Madison, WI, the University of Wisconsin-Madison has taken a number of steps in response to the COVID-19 situation such as switching to online classes for the remainder of the semester and having most employees work remotely. The full details of UW-Madison’s response can be found here: covid19.wisc.edu.
Despite the disruptions, part of the Wisconsin Idea is that the activities of institutions like UW-Madison should provide benefits to residents in all reaches of the state. To that end, the UW Insect Diagnostic Lab remains open to provide insect/arthropod identification and outreach services to residents of Wisconsin, with some notable changes. Bookmark this page for updates which will be posted as they arise.
General Diagnostics & Questions:
Many of the services of the IDL, such as email photo submissions, remain unchanged. Important points are noted below:
Arthropod ID requests (insects, spiders, etc.) can still be submitted to the UW Insect Diagnostic Lab
Digital photographs are the best way to submit an ID request in the time of COVID-19. See this webpage for required information and tips on submitting insect images.
Physical samples can also still be submitted to the diagnostic lab by mail. Per UW-CALS policy, the IDL’s building on campus is locked until further notice and samples cannot be dropped off in-person at this time. Please be aware that processing times will be slightly longer than usual for mailed-in samples, but I will be able to check for mail submissions on a regular basis. Please see this webpage for instructions on how to submit physical samples by mail.
General insect questions can still be submitted by email to firstname.lastname@example.org (best option) or by phone. I will continue to have regular email access while working remotely, but phone responses will likely be delayed. Email will be the best way to reach me for the time being.
The UW Insect Diagnostic Lab regularly provides outreach around Wisconsin via public radio, workshops, public seminars, and other venues. Unfortunately, the COVID-19 situation is impacting in-person delivery of this outreach. See below for additional details:
In-person presentations provided by the UW Insect Diagnostic Lab have been cancelled until further notice.
If interested in distance education (via Zoom, Skype, Google Hangouts, etc.), feel free to reach out to me by email (email@example.com) to coordinate.
Fleas (Order Siphonaptera) can be an unwanted surprise—no one wants fleas on their pets or in their house. Our commonest flea on both cats and dogs in the Midwest is the “cat flea” (Ctenocephalidesfelis), and this same species can also live on a wide range of wild animals. Cat fleas may be annoying but can be controlled with a diligent multi-pronged approach: chatting with your veterinarian to pick a proper treatment for your pet and regular and thorough vacuuming. In heavy infestations, carpets and furniture may also need to be treated. While fleas could be encountered anytime of the year, I see the vast majority of flea cases at the UW Insect Diagnostic Lab in late spring and summer. In contrast, cases of fleas are few and far between during the winter months due to the dry conditions and lower temperatures which can be hard on these insects.
There is one type of “flea”, however, that I see regularly through the winter months—the “snow flea”. Snow fleas (Hypogastruranivicola and close relatives) aren’t actual fleas and rather than a pest, these harmless creatures are a beneficial curiosity. Their cold tolerance and ability to launch themselves into the air account for their nickname.
The snow fleas we’re talking about technically aren’t even insects and belong to a closely related group of arthropods known as springtails (Collembola). Springtails get their name from the furcula—an anatomical structure on the underside of their bodies, which springs downwards to catapult them up into the air. Springtails can’t “jump” very far by human standards given their tiny size (less than a tenth of an inch long), yet they can easily launch themselves many times their own body length in a mere blink of an eye (video).
The snow flea is unusual for springtails (and most arthropods) in the fact that these creatures can remain quite active during the winter months. As discussed in this post from last March, insects and other arthropods have a variety of strategies to make it through winter, ranging from migration to freezing solid in some cases. The vast majority of arthropods are inactive during winter, but some, like the snow flea, seem perfectly content wandering out on the snow. With their tiny size and dark grayish bodies, snow fleas can almost look as if someone had dumped out a pepper shaker on the snow.
Their ability to remain active at frigid temperatures is due to the concentration of specific proteins in their bodies, which serve as a cryoprotectant or natural “antifreeze”. During the rest of the year, these creatures simply blend in amongst fallen leaves where they scavenge upon decaying materials and help with nutrient recycling.
These creatures are truly a winter curiosity if you haven’t encountered them before. The next time you’re out snowshoeing or cross-country skiing, keep an eye out for these tiny acrobats on the snow.
Final Note: Overseas, our friends in the UK have different creatures they refer to as snowfleas—insects from the genus Boreus, which we’d call “snow scorpionflies” in our area.
Despite being winter, Wisconsin has recently been in the news because of insects—blister beetles—and their potentially deadly impacts on horses. In addition to their medical significance, these insects have a long and interesting story with some surprising twists.
Blister beetles comprise a diverse family of insects (Family Meloidae), with over 3,000 species known from around the globe. In the Unites States, we’ve got approximately 400 species, with the bulk of the diversity centered in the dry southwestern part of the country. However, this group is widely distributed across the lower 48 states, with nearly 30 species known from Wisconsin alone.
The common blister beetles species of the Upper Midwest are oblong and typically range from ½-inch to ¾-inch long, although other species can vary in size. Unlike the stereotypical “crunch” of most other beetles—think of accidentally stepping on a May/June beetle—blister beetles have softer bodies and are similar to fireflies in this regard. A few of our Midwestern species are striped or brightly colored, but many common species are dark-colored, being mostly black, grey, or a dark metallic green.
But don’t let their drab appearance fool you. Blister beetles wield a potent defensive toxin—cantharidin. In adult blister beetles, this compound is produced by males, which provide it to females during courtship. Females then use it to chemically protect their eggs.
The properties of cantharidin are well-known, and this chemical irritant and its coleopteran source have a surprising history dating back thousands of years. For example, Pliny the Elder knew of the toxic effects and mentioned blister beetles in his writings. Old medical reference books list a number of potential uses for cantharidin, ranging from the treatment of skin conditions to a supposed remedy for baldness. However, cantharidin might have harmed more than it helped. Dermal exposure has long been known to cause irritation and blistering—hence the common name of “blister beetles”. If ingested, symptoms can be much more serious: severe irritation of the gastrointestinal and urinary tracts, kidney and heart damage, and a cascade of other undesirable effects. Human deaths have been recorded in the medical literature and in a recent report, a soldier consumed a single blister beetle on a dare and ended up hospitalized with acute kidney injury.
Surprisingly, cantharidin was also historically deployed as an aphrodisiac—Spanish fly. In the days before the little blue pill, Spanish fly was known for its ability to irritate the urethral lining to produce a “stimulating” effect. In one historical report, French Legionnaires in North Africa complained of priapism after feasting upon frogs that had happened to eat blister beetles (frogs seem to be unaffected by cantharidin).
Humans aren’t the only creatures affected by blister beetles and horses are especially sensitive. Ingestion of only a few grams of cantharidin can potentially be lethal to an adult horse. Blister beetle poisoning is rare in equines, but can occur if the adult beetles happen to be in an alfalfa field feeding on blossoms at the time of harvest and are crushed by farm equipment. In an unfortunate situation, blister beetles have recently been reported in connection with the deaths of over a dozen horses in Mauston, Wisconsin.
Blister beetles have another noteworthy Wisconsin connection from the history books. The former governor of Wisconsin, Robert “Fighting Bob” La Follette, was well-known for his progressive politics as well as an impressive head of hair. His secret?—a hair tonic containing cologne, oils of English lavender and rosemary, and a cantharidin-containing tincture made from blister beetles.