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.
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.
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.
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.
“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…
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.
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.
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 ofadult 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.
Will we see Brood X cicadas in Wisconsin or the upper Midwest this year? Read on to find out: Cicadas—they’re all over the news and soon to be out by the billions. All this buzz is about periodical cicadas, a group of species from the genus Magicicada which emerge once every 17 years (or every 13 years in some cases). Periodical cicadas are only found in the eastern United States and vary by location and the timing of their activity. To help categorize these insects, entomologists refer to each cohort of cicadas as a “brood” and have numbered them with Roman numerals. This year’s cicadas are referred to as Brood X (i.e., Brood ten) and last emerged in 2004.
Periodical cicadas are amongst the longest lived insects and their long life span and massive emergences are believed to be a survival strategy—by overwhelming predators with sheer numbers, they simply can’t all be eaten. But the wait for their appearance is a long one. Periodical cicadas spend 17 years below ground as juveniles (nymphs) feeding on the sap from tree roots, before making their way above ground. Their emergence is associated with soil temperatures, and when the soil has warmed to 64˚F, they emerge. This corresponds to parts of April, May, or June depending on the location on the map. Once they make their way above ground, the cicadas molt and transform into adults. Shortly thereafter, a raucous mating free-for-all commences. After mating, the females cut small slits into twigs of trees to deposit their eggs. The eggs hatch and the juveniles head to the soil for their lengthy development. Periodical cicadas don’t live long as adults (a matter of weeks), so it’s a long build up to a noisy grand finale.
With all the attention in the news, many Wisconsinites and other Midwesterners are wondering if they’ll be able to see or hear Brood X cicadas in their area this year. For Wisconsin, Minnesota, Iowa, and most of Michigan and Illinois the answer is no—although they aren’t terribly far away either. Brood X cicadas can be found in over a dozen eastern states, but primarily emerge in three main pockets:
Indiana, Ohio and nearby slivers of eastern Illinois and southern Michigan
Southern Pennsylvania and parts of nearby Delaware, Maryland, Virginia, New Jersey, and New York
Eastern Tennessee and nearby parts of North Carolina and Georgia
While we won’t see Brood X cicadas here in Wisconsin, we will see other periodical cicadas in the not so distant future. Wisconsin is home to Brood XIII cicadas, which last emerged in 2007, meaning that the next big emergence in the Badger State is only a few years off in 2024. In the meantime, we’ll still see and hear plenty of our typical “dog day” cicadas during the warm days of summer. To learn more about Brood XIII cicadas in Wisconsin, check out this post from last year.
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”.
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.
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.
It’s a funny world we live in. We hear regular reports of insect declines in the news and still get bombarded with constant ads for services pitching a mosquito free yard all summer and a grub free lawn. But what about simply appreciating insects and the critical roles they play in our everyday lives?
That’s a goal of the first ever Wisconsin Insect Fest being held at the Kemp Natural Resources Station in Woodruff, Wisconsin later this month. The two-day event—being held on Friday, July 26th and Saturday, July 27th—is a celebration of insects.
Wisconsin Insect Fest is free, open to the public, and will feature a wide range of activities for insect enthusiasts of all ages. Topics will range from how to observe and collect insects, to the role of insects in the ecosystem, entomophagy, and even forensic entomology. The Wisconsin Insect Fest will also feature The Great Wisconsin Bug Hunt—a 24-hour BioBlitz activity to see just how many arthropods can be spotted at the Kemp station in a 24-hour period (including a night time activity in conjunction with National Moth Week).
If you love insects, join in the festivities at the Wisconsin Insect Fest later this month or check out the event website for details: tinyurl.com/WisconsinInsectFest