Category Archives: Medical Entomology

Masked Hunter Bugs: Another Kissing Bug Look-Alike

“I think I’ve found a kissing bug and wanted to report it” is a surprisingly common line I get at the UW Insect Diagnostic Lab.

I’ve previously written about kissing bugs, but to quickly recap: these are blood-feeding assassin bugs found primarily in South and Central America.  Kissing bugs tend to be associated with vertebrate nests outdoors but can bite humans and can also carry Trypanosoma cruzia parasite that causes Chagas disease.  Due to this concern, I see a spike in website traffic and “reports” of suspected kissing bugs just about any time there’s national news coverage of these insects. While many kissing bug species exist, the vast majority are restricted to tropical and subtropical areas.  The northernmost species—the eastern conenose kissing bug (Triatoma sanguisuga)—ranges from Latin America as far north as southern Illinois.

Eastern conenose kissing bug adult.
Eastern conenose kissing bug adult. Photo credit: Robert Webster, via Wikipedia

Insects don’t care for geopolitical boundaries, but when humans shade in the entire state of Illinois on a distribution map of kissing bugs, it gives the false impression that these insects are on the tollway marching towards Wisconsin’s southern border.  However, the eastern conenose kissing bug is rarely spotted in the northern parts of its range and there has never been a verified case of kissing bugs from within Wisconsin.

The regular occurrence of false reports can likely be attributed to hype in the news combined with a good ol’ case of mistaken identity.  It turns out that there are a number of common insects that can resemble kissing bugs.  One of these, the western conifer seed bug (Leptoglossus occidentalis), is regularly encountered in the upper Midwest because these insects sneak indoors in the fall just like boxelder bugs.  Recently, the commonest look-alike I’ve been getting reports of is the masked hunter bug (Reduvius personatus), which can also be encountered indoors.

If you aren’t familiar with masked hunter bugs, there’s a good reason why these insects can sometimes mistaken for kissing bugs—they’re technically kissing cousins.  Both kissing bugs and masked hunter bugs belong to the assassin bug family (Family Reduviidae).  This is a diverse family of approximately 7,000 species worldwide and we have dozens of common species in the Midwest.  The vast majority of these species (including masked hunter bugs) are really beneficial predators of other arthropods and are of little medical importance.  In theory, if you picked up and mishandled one of our Midwestern assassin bugs species, it could bite—likely feeling similar to a wasp sting—although that’s about the worst it could do.

Juvenile masked hunter bug camouflaged with debris.
Juvenile masked hunter bug camouflaged with debris. Photo Credit: Chiswick Chap, via Wikipedia

Masked hunter bugs are readily identifiable, although the nymphs (juveniles) can have you scratching your head if you haven’t encountered them before.  The nymphs are often ¼” – ½” long and camouflage themselves with bits of lint and other debris—as a result, they can resemble miniature walking dust bunnies.  Once you recognize this disguise, they’re easy to identify.

Masked Hunter Bug Adult.
Masked Hunter Bug Adult. Photo credit: JP Hamon, via wikipedia

Adult masked hunter bugs are slender, roughly ¾” long, and entirely dark coloured.  They have long, thin legs & antennae and stout beak-like mouthparts which they use to feed on insects and other arthropod prey.  Several key features help distinguish masked hunter bugs from eastern conenose kissing bugs:

  1. Masked hunter bugs are entirely dark while eastern conenose kissing bugs have red on their body
  2. Masked hunter bugs lack the projecting “conenose” present on the head of kissing bugs
  3. Masked hunter bugs have a bulging, “muscular” appearance of their prothorax (trapezoidal region behind the head) when viewed under magnification
  4. Masked hunter bugs have stout beak-like mouthparts while kissing bugs have long, slender mouthparts when viewed under magnification

Side-by-side comparison of a kissing bug and a masked hunter bug.
Side-by-side comparison of a kissing bug and a masked hunter bug. Photo Credit: Devon Pierret and PJ Liesch, UW Insect Diagnostic Lab. [Click for full sized version]
When it comes to kissing bugs, we simply don’t have these insects in the Upper Midwest, but we do have look-alikes.  For side-by-side diagrams showing an eastern conenose kissing bug compared to common look-alikes, visit the ID Guide page on this website: labs.russell.wisc.edu/insectlab/visual-id-guides/

Black Flies: Out for Blood

Mosquito season has officially kicked off in Wisconsin, meaning the omnipresence of repellents for the foreseeable future.  If mosquitoes have redeeming properties, it’s that they at least serve as food for a wide variety of animals and can even act as pollinators in some cases.  When mosquitoes bite, they do so with surgical precision that would make a phlebotomist green with envy.  Simply reading about mosquitoes might make you want to scratch, although on the spectrum of biting flies, things could be much more sinister…

Also very active at the moment in Wisconsin are black flies (Family Simuliidae) and our state is home to 30 species of these tiny sanguivores.  Black flies—or “buffalo gnats” due to their hump-backed appearance—are deceptive creatures for their small size (~ 1/8″ long).  You usually don’t notice them as much by sound like buzzing mosquitoes, but when they land to feed, these tiny flies are vicious.  Rather than using needle-like mouthparts to delicately probe for blood vessel like mosquitoes, black fly mandibles resemble the jagged edge of Rambo’s survival knife which they use in a “slash-and-slurp” approach.  These mouthparts slice into flesh to create a pool of blood which they then consume.  If this sounds unpleasant—it is!  Reactions to black fly bites can sometimes be severe, with fever and enlargement of nearby lymph nodes.  In addition, their sheer numbers can take a psychological toll and can be a strong test of one’s fortitude if you must be outdoors during peak black fly season.

Adult black fly taking a blood meal. Photo Credit: Credit: D. Sikes, via Flickr.

Of the 30 species in Wisconsin, only a handful actually bite humans.  Other species are “picky eaters” with a strong preference for other animals.  The species, Simulium annulus, specializes on common loons and in “bad” years the constant pestering can force adult loons to abandon their nests.  Other birds, such as purple martins and bluebirds can face high rates of chick mortality when the black flies are bad.  Pets, like dogs can commonly get bites and large pinkish welts on the soft skin of their belly.  Dairy cows can be harassed to the extent that feeding and weight gain is greatly reduced and milk production all but ceases.  In some cases, large animals including deer, cows, and horses have been killed outright by black flies.

With that said, if you’ve ever encountered an outbreak of black flies, you’d likely remember.  If you haven’t bumped into black flies before, you’re perhaps in a good spot on the map.  The larvae of many black fly species tend to be associated with streams and rivers, meaning that geography can play a role with outbreaks.  Within the state, areas near the Wisconsin River and other large rivers and streams tend to see the most intense black fly activity.  Black flies can be even worse to the north.  These insects can be notoriously bad in the Boundary Waters Canoe Area in June, and in Canada black flies have even been enshrined in film and a surprisingly catchy folk song.

Black fly larvae in a river. Photo credit: GlacierNPS via Flickr

If there’s good news about black flies, it’s that the adults are short-lived.  Wisconsin tends to see a blitz of activity spanning a 2-3 weeks in late spring.  When black flies are active, the best approach is to layer up with long sleeves, break out the repellents like DEET, and use a head net if needed.  If you’re in an area with intense black fly activity, cutting back on outdoor activities until these insects run their course for the year may be the simplest option.

What’s Trending? Ticks and Lyme Disease

This month’s post features contributions from Dr. Bieneke Bron


As stories about measles and vaccinations circulate in the news, it’s easy to lose track of other emerging health threats.  May is Lyme Disease Awareness month, and if you want to look at an emerging health threat particularly relevant to the Midwest, look no further than deer ticks and Lyme disease.

Adult female deer tick (Ixodes scapularis). Photo credit: Robert Webster / xpda.com / CC-BY-SA-4.0 via Wikipedia.

A Brief History of Deer Ticks and Lyme Disease:
The Lyme disease story is surprisingly new to Wisconsin and deer ticks are something that our grandparents didn’t have to deal with while growing up.  It wasn’t until the late 1960’s that our first deer ticks were documented in northern Wisconsin. At the time, this particular tick was known from more southern locations, so the first Wisconsin reports were noted as a curiosity in the scientific literature.  In actuality, this marked an early foothold of deer ticks in the region, which have spread rapidly.  Fast forward 50 years and deer ticks are widely distributed around Wisconsin and surrounding states.

Deer ticks are only one component of the Lyme disease equation. The spirochete bacterium Borrelia burgdorferi (or the closely-related B. mayonii) must be transmitted by these ticks to cause Lyme disease in humans.  Similar to the deer tick situation, Lyme disease has had an interesting recent history.  Research from the Yale School of Public Health suggests an ancient origin of Borrelia burgdorferi, but the first clinical cases of Lyme disease weren’t formally documented in the medical literature until the 1970’s.  At that time, an unusual cluster of juvenile arthritis cases with an accompanying rash helped researchers characterize the disease near Lyme, Connecticut*.  It wasn’t until the early 1980’s that the roles of deer ticks and Borrelia burgdorferi were recognized.

Skip ahead a few decades and the numbers for Lyme disease have increased steadily.  Today Lyme disease is the most commonly reported arthropod-borne disease in the US with over 40,000 confirmed and probable cases in 2017 alone.  Looking at Wisconsin’s statewide averages, approximately 20% of deer tick nymphs (juveniles) and 40% of adult deer ticks are carrying Lyme disease, which are alarmingly high percentages.

Deer tick nymphs (juveniles) next to chia seeds, sesame seeds, flax seeds and a penny for size reference. Photo Credit: Dr. Bieneke Bron, MCE-VBD.

Tracking Ticks with Mobile Technology:
With the changing tick and tick-borne disease situation over the last 50 years, understanding the factors that influence where and when ticks are encountered is more important than ever before.  Researchers at the Midwest Center of Excellence for Vector-Borne Disease and the Northeast Regional Center for Excellence in Vector-Borne Diseases have teamed up to develop The Tick App—a mobile app to help gather critical clues to better understand human exposure to ticks.  The app, available in iTunes and GooglePlay, not only allows the public to contribute valuable data to tick researchers, but the app provides helpful tips on tick identification, activity, and precautions to take.  During the tick season, the researchers will also identify ticks from the images submitted in the app.

As we move into peak tick season, Midwesterners should be aware of ticks and take appropriate precautions to protect themselves [Recommended reading: the ABCs of Tick Season].  Learn more about The Tick App by visiting thetickapp.org or follow on Twitter @TickAppOnTour.


*Interestingly, a 57-year old physician from Medford, Wisconsin, was diagnosed with the hallmark rash of Lyme disease (erythema migrans) in 1969 [Scrimenti 1970, Arch Derm].  Just imagine, Lyme disease being known as Medford disease…

2018’s Top Trends from the Diagnostic Lab (Part 2)

In this post, we’re continuing to count down the University of Wisconsin Insect Diagnostic Lab’s top arthropod trends of 2018. This is the second half of a two part series; the first half can be found here.


5) White-Lined and Other Sphinx Moths:
The white-lined sphinx moth (Hyles lineata) can be a common species, so encountering one of the 3 inch long hornworm caterpillars isn’t unusual. However, these caterpillars can also be encountered in massive road-traversing hordes if the conditions are just right. From midsummer onwards, large numbers of these caterpillars were observed around the state—in some cases by the tens of thousands. If you didn’t spot any of the caterpillars themselves, you might have encountered the large adult moths with their hummingbird-like behaviour in late summer. Several other sphinx moths species also had a strong presence in 2018, such as the clearwing hummingbird moths and the tobacco and tomato hornworm caterpillars which can regularly be encountered in gardens as they munch away on tomato and pepper plants.

Large, dark-colored hornworm caterpillar of the white-lined sphinx moth on a plant
Large, dark-colored hornworm caterpillar of the white-lined sphinx moth. Photo submitted by Ted Bay, UW-Extension

4) Sawflies:
Sawflies, the caterpillar copycats of the insect world, are a diverse group, so they’re always present to some extent. Last year saw an unexpected abundance of two particular types in Wisconsin—the dogwood sawfly and the non-native Monostegia abdominalis, which feeds on creeping Jenny and related plants from the loosestrife group (Lysimachia species). While sawflies are plant feeders, dogwood sawflies can also damage the soft wood of a home’s siding or trim when these insects excavate small chambers to pupate in. The UW Insect Diagnostic Lab saw a distinct bump in reports of wood damage from the dogwood sawfly last year.

Whitish larva of the dogwood sawfly curled up on a dogwood leaf
Larva of a dogwood sawfly showing the whitish, waxy coating. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab

3) Armyworms:
True armyworms (Mythimna unipuncta) can be a dynamic and sporadic pest in the Midwest. This species doesn’t survive the cold winters of our area, so adult armyworm moths must invade from the south each spring. Depending on national weather patterns, the arrival of the adult moths can vary significantly from year to year. If an early mass arrival is followed by abundant food and ideal conditions for the ensuing caterpillars, large populations can result. Once they’ve arrived, true armyworms can go through 2-3 generations in the state and this second generation of caterpillars made an alarming appearance in mid-to-late July. Under the conditions last summer, massive hordes of these caterpillars decimated crop fields before marching across roads by the tens or hundreds of thousands to look for their next meal. In some cases, that next meal included turfgrass, meaning that some Wisconsinites came home from work to biblical hordes of caterpillars and half-eaten lawns in late July.

Striped caterpillar of the true armyworm
Caterpillar of the True Armyworm (Mythimna unipuncta). Photo Credit: Lyssa Seefeldt, University of Wisconsin-Madison Extension

2) Monarch Butterflies:
Much to the delight of fans and conservationists, the iconic monarch butterfly (Danaus plexippus) appeared to have a banner year in the Midwest in 2018. Reports and observations of high numbers of monarchs poured into the Insect Diagnostic Lab during the summer months. As comforting as these reports were, the butterflies still faced a perilous 2,000 mile journey to reach their overwintering grounds in Mexico.  The most consistent measurement of the eastern monarch population comes from estimating the area occupied by the densely-packed overwintering butterflies.  In late January the latest count was released with encouraging news—the eastern monarch population is up 144% over last year and is estimated to be the largest in over a decade.  In contrast, the western monarch population overwinters in southern California and has recently dipped to alarmingly low numbers. Regardless of the winter assessments, monarchs face tough challenges and Wisconsinites are encouraged to help conserve this iconic species.  The Wisconsin Monarch Collaborative recently launched a website with resources for those wishing to join the effort.

Seven monarch butterflies nectaring on a flower
Multiple monarch butterflies nectaring on a single plant in August. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab

1) Floodwater Mosquitoes:
Mosquitoes snagged the top spot on 2018’s list for good reason. The upper Great Lakes region is home to over 60 different mosquito species, but one subset—the “floodwater” mosquitoes—drove the storyline last year and impacted outdoor activities through much of the spring and summer months. Mosquitoes in this group, such as the inland floodwater mosquito (Aedes vexans), flourish when heavy rains come. Last year’s mosquito season kicked off in force with a batch of pesky and persistent floodwater mosquitoes just before Memorial Day weekend. Mosquito monitoring traps in southern Wisconsin captured record numbers of mosquitoes shortly thereafter. Later in the year, the Midwest experienced an unprecedented series of severe rainstorms, setting the stage for an encore performance of these mosquitoes. It was this second explosion of mosquitoes that caught the attention of anyone trying to enjoy the outdoors in late summer—a time of the year when mosquitoes are typically winding down in the state.

Ephemeral pools of water created ideal conditions for floodwater mosquitoes in late summer. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab

September’s Mosquito “Madness”

While much of our insect activity in the Midwest slows down as summer draws to a close, some areas have seen an unusual increase in mosquito activity recently.  In Wisconsin, we generally expect mosquitoes to be “bad” from late spring through the summer months, but these pesky sanguivores typically fade away as autumn approaches.  September of 2018 has definitely bucked the trend, and mosquito pressure has been very high in many parts of the state and region this month.

As with other mosquito stories, the common denominator is water—in this case, the unprecedented rainfall events in late August and early September.  During this time, a series of storms dropped heavy rains across large swaths of Wisconsin and surrounding states.  Much of Wisconsin received several inches of rain, and some southern counties were bombarded with 10+ inches of rain in short periods of time.  Devastating flooding ensued, and it was only a matter of time before the mosquitoes responded as well.

Flooding caused over $200 million in damages in Wisconsin alone and set the stage for September’s unseasonably high numbers of floodwater mosquitoes. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab

Surprisingly, not all mosquitoes can take advantage of floodwaters and some species have a strong preference for more permanent bodies of water, such as tree-holes, man-made objects, marshes, and other areas that can hold water for weeks or months on end.  Out of the 60+ mosquito species in the Midwest, it’s a much smaller subset that has flourished lately—a group appropriately called the “floodwater mosquitoes” for their ability to use temporary water sources to their advantage.  Members of this group, including the currently-abundant “inland floodwater mosquito” (Aedes vexans), tend to lay eggs in low-lying areas without water.  Laying eggs away from water may seem like a counterintuitive strategy, but the hardy eggs simply bide their time until heavy rains arrive—in some cases, years later.

Relying upon temporary resources can be a risky strategy; if the waters dissipate too quickly,  stranded larvae or pupae can be doomed.  Floodwater mosquitoes have evolved to race against the clock, with eggs that hatch shortly after exposure to water, followed by hasty growth and development.  Under the right conditions, it can take less than a week for these mosquitoes to make it to the adult stage.  This scenario is exactly what played out in our area—the rains came, followed shortly thereafter by hungry adult mosquitoes.

The “inland floodwater mosquito” (Aedes vexans) is currently abundant in the Midwest. Photo Credit: Sean McCann, via Flickr

With the unseasonably high mosquito pressure this September, one of the commonest questions has been, “when will it stop?!”  While the mosquitoes have undeniably been bad lately, we’re past the worst of the situation.  Mosquitoes and other insects are “cold-blooded” creatures, so there’s a general relationship between warmer temperatures and insect activity. Most of our insects in the Midwest become lethargic when temperatures dip into the 50s; below 50˚F mosquitoes are often too lethargic to fly, let alone pursue a blood meal.  We saw unusually high mosquito activity in early- and mid-September when temperatures remained in the 70s and 80s most days.  Looking at the weather for the near future, many parts of Wisconsin are expecting more seasonal temperatures, which will provide relief.  Mosquitoes might still be encountered on warm fall days, but evening temperatures may simply be too chilly for mosquitoes to go about their business and impending frosts will be the final “nail in the coffin” for September’s floodwater mosquitoes.

In the meantime, the best way to deal with the late season mosquitoes may be to embrace “flannel season” and put on some long-sleeved layers as a physical barrier to bites, and use  EPA-approved repellents as needed (such as on warm days).  Avoiding prime mosquito feeding times (dawn/dusk) and good mosquito habitat can help you avoid bites as well.  It may be sad to see summer go, but the changing leaves and cooler temperatures also signal the winding down of mosquito activity for the upper Midwest.

To Boldly Go Where Man Has Gone Before: Pests on the Move

Since the earliest days of mankind, we’ve excelled at exploring and expanding our presence to nearly every spot on the map With all our wanderlust, we’ve been equally adept at taking other species with us as we go—often with unintended consequences. 

In some situations, species have been deliberately moved by humans: livestock to the new world, the introduction of birds from Shakespeare’s plays into Central Park,  and even the notorious gypsy moth was transported from Europe in a failed attempt at an American silkmoth industry On top of that, there’s an extraordinarily long list of species that have been accidentally moved, with significant impacts Stowaway rats on the ships of European explorers and traders would be one of the most notorious examples Rats introduced to new island environments wreak havoc on native birds and reptiles by devouring vulnerable eggs Insects have also been transported around the globe with devastating results and some of North America’s most important and emerging insect pests originate elsewhere on the planet: Japanese beetle, emerald ash borer, brown marmorated stink bug, and the spotted lanternfly.

Aedes sp. mosquitoes preparing for a blood meal.  Photo Credit: Ary Farajollahi, Bugwood.org.

One of the insects best adapted to follow humans is the notorious mosquito Certain mosquito species (peridomestic species) possess traits that allow them to take advantage of conditions in areas disturbed by humans and thrive in those spots.  With humans came environmental modification, construction, and discarded trash of one kind or another.  Some mosquitoes might have originally relied on the water pooled in natural containers, such as rotted out tree stumps to reproduce, but can just as easily take advantage of water-filled containers, ditches, and other artificial habitats.

In modern times, automotive tires have become a key habitat for certain mosquito species Tires not only are perfect objects for holding water for extended periods, but they also provide the dark, sheltered habitat favored by some female mosquitoes looking to lay eggs Tires are an important way for mosquitoes, like the Asian Tiger Mosquito (Aedes albopictus) to be moved into and around the US (including the Midwest) Other species, like the Asian Rock Pool Mosquito (Ochlerotatus japonicus), are also easily transported in human materials.

Hyacinth flower sold from a local store, including a vase pre-filled with water. Photo credit: PJ Liesch, UW Insect Diagnostic Lab.

A recent case at the UW Insect Diagnostic Lab illustrates the ease with which non-native mosquitoes can be moved around the country In the first part of 2018, stores have been selling hyacinth bulbs in vases pre-filled with water as a way to force the bulbs to bloom into a flash of color during the dreary winter months In a recent discovery in southeastern Wisconsin, a vase purchased at a local store ended up yielding half a dozen larvae of the non-native Asian rock pool mosquito.  The exact origin of the mosquitoes isn’t known at this time.

A bonus surprise with the flowers—larvae of the Asian rock pool mosquito (Ochlerotatus japonicus). Animation credit: PJ Liesch, UW Insect Diagnostic Lab.

These mosquitoes won’t be much of a concern in the grand scheme of things as Ochlerotatus japonicus has been present in Wisconsin for over a decade and is already established hereHowever, such cases do leave open the possibility of non-native mosquitoes being moved into parts of the country where these pests have not been encountered beforeWhere humans go, pests will boldly follow.

Under the Microscope: Arthropod Trends of 2017

Over 2,500 cases flowed through the doors of the UW Insect Diagnostic Lab last year, ranging from the typical June beetles through bizarre creatures that most humans will never see in their entire lives (like the itch-inducing pyemotes grain mite).  Perhaps Forrest Gump said it best when he quipped, “life was like a box of chocolates—you never know what you’re gonna get.”  A distinction amongst insects, however, is that the “box” contains 20,000+ possibilities in Wisconsin alone and over well 1,000,000 globally.  With that said, a year at the UW Insect Diagnostic Lab is like having one humongous, box of really awesome chocolates, without all the calories.

Finding a pyemotes itch mite is like trying to find a needle in a haystack, except in this case these microscopic mites were in a farmer’s batch of corn. Photo credit: PJ Liesch, UW Insect Diagnostic Lab

With insects and related creatures, the weather can of course have a big impact and there definitely were examples of this in 2017.  The current cold winter aside, the last two winters had been otherwise mild, giving a few insects suited for warmer conditions a chance to inch their way northward.  Last spring and summer, this meant a bunch of sightings of an otherwise uncommon bee for our area known as the carpenter bee due to its habit of tunneling into unpainted cedar trim and other wood.  In a typical year, I might see a few cases out of the southeastern corner of Wisconsin, but 2017 had regular reports of these bumble bee look-alikes during the spring and summer months.  Similarly, praying mantids often meet their maker at the hands of a cold winter, but were surprisingly abundant in late summer and fall of last year.  Ticks were also extremely abundant last spring and with the rainy start to the summer, mosquito numbers were at an all-time high in some traps.  Mosquitoes were also a big deal in the news, with Wisconsin’s first confirmed reports of the Asian Tiger Mosquito last July.

Asian Tiger Mosquito (Aedes albopictus). Photo credit: James Gathany, Centers for Disease Control

The creature that amassed the most phone calls and emails in 2017 was the notorious Japanese beetle, which likely also benefited from the warmer than average winters these past few years.  For Wisconsin gardeners and farmers, the Japanese beetle is certainly a formidable foe, but at least there are ways to mitigate the damage.  In contrast, there’s another destructive pest wiggling its way into the spotlight in the state, which is much more difficult to control—an invasive earthworm commonly known as the jumping worm.  While they may not be insects, these earthworms are creepy-crawly and can wreak havoc in  gardens and flower beds, so I received a fair number of reports and questions.  What stood out to me in last year was the rapidity with which these destructive worms have been moved around the state (moved—as in humans have moved soil, plants, mulch, and similar materials).  Jumping worms were first found in the state in 2013 (in Madison), but have now been spotted in roughly half of the counties in Wisconsin.  To make matters worse, we don’t have any highly effective tactics to prevent these worms from turning rich garden soil into the consistency of dry, crusted coffee grounds—gardeners beware!

Speaking of invasive species, the emerald ash borer has continued its march through the state and now has footholds in some of our northern counties including Chippewa, Douglas, Eau Claire, Marathon, Marinette, Oneida, and Sawyer counties.  Unfortunately, our greatest concentrations of ash trees are in the northern part of the state (e.g. black ash in swampy areas), and the loss of ash from northern wetland areas could result in significant ecosystem effects.  Other recent invaders like the spotted wing drosophila and the brown marmorated stink bug had busy years as well.

Rusty patched bumble bee (Bombus affinis) visiting a flower in Middleton, WI. Photo credit: Rick Terrien

In other insect news, it seemed to be a good year for monarch butterflies in 2017, and the rusty-patched bumble bee finally made it onto the federal endangered species list. I was pleasantly surprised by a number of confirmed sightings of the rusty-patched bumble bee in the state as well. Perhaps my favorite “bug” story for the year involved black widow spiders.  It’s not common knowledge, but we do technically have a native black widow species in the state (Northern Black Widow, Latrodectus variolus).  It’s a reclusive species and is rarely encountered in Wisconsin, but reports trickled in once or twice a week at some points during the summer months (details to follow in a future blog post).

With so many cases last year, we’re really only touching the tips of the antennae.  If you’re interested in hearing more of the unusual stories from the UW Insect Diagnostic Lab, I’ll be giving a “highlight” talk on May 4th on the UW campus.

 

 

 

A Mysterious Tingling Sensation: Bird Mites

If I had to pick the most misunderstood creature I regularly encounter at the diagnostic lab, it’d be bird mites.  Perhaps you’ve never even heard of bird mites—tiny arachnids that suck the blood of the birds nesting in your back yard.  Under the right conditions, those same mites can wander indoors and  inadvertently bite humans.

If you haven’t heard of bird mites before, your first inclination may be to do a quick Google search to learn more.  Unfortunately, the Internet is rife with misinformation about these creatures.  In the age of fake news, here’s another gentle reminder to assess the credibility of online sources.  I’ve encountered websites full of misleading, downright wrong, and in some cases, dangerous management recommendations about bird mites.  I’ve also had to console clients on multiple occasions because they’ve read about bird mites online—only to believe that the mites will be infesting themselves, their homes, and vehicles indefinitely.

Although small (<1 mm long), bird mites can be seen with the naked eye, and their nearly constant movement helps give them away.  Perhaps the best description of their appearance is walking flakes of pepper.  Under magnification, bird mites have a somewhat tick-like appearance with their eight legs and long, prominent mouthparts.  The mites are often whitish in color with some black on the body but can turn darker after feeding.   Each year, I typically bump into 10-20 bird mite cases during the spring and summer months.  The mites can actually be quite common but simply aren’t encountered unless you have a bird nest very close at hand: under a back deck, on a patio light fixture, in a gutter or a damaged soffit area or in a shrub just outside a bedroom window.

Bird mite. Photo Credit: Whitney Cranshaw, Bugwood.org

True to their name, bird mites are parasites that feed on the blood of birds.  These mites are often most noticeable when young birds have just left the nest and the mites wander desperately looking for a blood meal.  Without their avian host, bird mites have a short time to live, but they can make their way indoors where they can crawl on and inadvertently try biting humans and pets.  Although the mites can be an itchy tingly nuisance, they can’t survive on humans or in homes for any significant length of time.  The literature suggests that off of their avian hosts, the common bird mites may be able to survive a matter of weeks under the most ideal of conditions.  In most cases, the conditions off the birds are so hostile (too dry) that survival is limited to a few days at best—especially in a modern home with air conditioning.

As with many pest control situations, eliminating the source of the problem often brings about rapid results and bird mites aren’t any different.  If you’ve found bird mites, removal of the bird nest once the birds have left the nest is the single most important step.  Like flipping a switch, mite activity typically drops off rapidly within a day or two of the nest being removed.  Indoors, desiccation is probably the biggest threat to bird mites, so running your AC and/or dehumidifier may  help hasten their demise.  Vacuuming, using sticky tape, or wiping up mites with a damp soapy cloth can all help eliminate any additional stragglers that made it indoors.  Pest control professionals typically also apply to residual product to nearby areas to help control any residual mites.

If you think you may be dealing with bird mites, contact the local University Extension service in your state/area for advice.

Don’t Be an (April) Fool: Look Out For Ticks

April Fools’ Day may be here, but the topic of ticks is anything but funny.  The Midwest is home to over a dozen tick species, although only a few of these are encountered regularly by people and/or pets and are of notable concern.  Nevertheless, the medical concerns posed by some species can be quite significant.  Our two most notorious species of ticks in Wisconsin and nearby states are the wood tick (aka American Dog tick) and the deer tick (aka black-legged tick).

The wood tick (Dermacentor variabilis) is perhaps our most commonly encountered tick and adults of this species are fairly noticeable with their relatively large size (~ 1/4  inch long).  Wood ticks can be associated with certain human diseases, such as Rocky Mountain spotted fever although the threat of this disease in the Midwest is low.  A complication regularly caused by this tick in the field of veterinary medicine is tick paralysis, which is a serious reaction to components of the tick’s saliva in situations where ticks have been attached to pets for extended periods of time.

Adult Female Wood Tick (American Dog Tick). Image source: CDC.

At the moment, the tick of greatest concern in the Midwest is the deer tick (Ixodes scapularis).  This is the species notoriously associated with Lyme disease, although it can also vector anaplasmosis, babesiosis, and other diseases.  This tick is noticeably smaller than wood ticks, making them more difficult to spot; adult deer ticks come in at a mere ~ 1/8 inch long.  Interestingly, deer ticks are relatively new to the upper Midwest and these ticks weren’t spotted in Wisconsin until the late 1960’s .  Fast forward 50 years and deer ticks can be found in nearly every corner of the state.  The high rate of infectivity (i.e., percentage of ticks carrying a disease) is worryingly high: approximately 20% of tick nymphs (juveniles) and 40% of adult ticks in Wisconsin are carrying the microorganism responsible for Lyme disease.  In certain spots in the state, the rate of infectivity has been documented at closer to 60% in some studies.  This high rate of infectivity combined with the recent ubiquity of deer ticks poses significant health risks to residents of the upper Midwest and nearly 30,000 confirmed Lyme disease cases are reported from across the country to the CDC each year.  What’s more alarming is that estimates from the CDC suggest that the actual number of Lyme disease cases may be an order of magnitude higher!

Adult Female Deer Tick (Blacklegged Tick). Image source: CDC.

So how will ticks and Lyme disease be in Wisconsin this year? Some scientists have predicted high tick and Lyme disease pressure in the eastern US in 2017.  While that topic has gotten a lot of attention in the news, this may not be the case in our state.  The thought behind the prediction is that high rodent populations (a host for juvenile deer ticks) may bolster deer tick numbers.  While this relationship was documented in certain geographic locations in a 2005 study, the relationship didn’t hold up across the board as a general predictor of tick activity and neither did weather patterns.  With that said, it’s difficult to get a reliable predictor of tick activity and Lyme disease pressure in a given year.  In addition, based on recent field observations by fellow entomologists, rodent populations don’t seem to be bursting at the seams at the moment in Wisconsin. Last year (2016) seemed to be an average tick year in the state and we may be in for more of the same this year.

Regardless of tick numbers, the threat of ticks and Lyme disease is still out there and isn’t something to be ignored.  Deer ticks can potentially be encountered anytime of the year that the temperatures are above freezing and the ground isn’t covered with snow.  While often thought of as a creature of the deep woods, ticks can also be found in suburban areas near parks and nature preserves, so vigilance is a must—even in your own backyard.  Below are some sound tips to help prevent issues with ticks this year:

  • Personal Protection: Long sleeved clothes can help prevent ticks from getting to skin. In addition, light-colored clothing can make it easier to spot ticks.
  • Repellents: A number of EPA approved repellents (such as DEET) can help repel ticks when properly used. Always consult the product label for important usage instructions (e.g., application to skin vs clothing, how often to reapply).  As another consideration, clothing can be treated with certain permethrin products (often sold at outdoor/camping stores) to provide long-term protection from ticks. Outdoor clothing impregnated with permethrin can also be purchased at outdoor clothing stores and can remain effective for extended periods of time.
  • Tick checks: To effectively transmit Lyme disease, deer ticks have to be attached and feeding for approximately 36 – 48 hours which means that daily tick checks can help find and remove ticks before they’ve had a chance to transmit Lyme disease. Tick checks can be an important precaution for both people and pets.
  • Protecting Pets: Family pets should be treated with a preventative flea and tick treatment. Consult with your veterinarian about the products recommended for your particular pet(s).  Lyme vaccines for animals are also available through your veterinarian.

Perhaps Mother Nature has a cruel sense of humor with her April Fools’ pranks—we finally have an end to the dreary days of winter only to move into tick season!