Tag Archives: In the News

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…

…An even earlier account of the Lyme-like “bullseye” rash was described in Europe by Arvid Afzelius in 1909.

Spring’s Coming…and so are the Insects

With daylight saving time beginning over the weekend and warmer temperatures knocking at our door, spring is finally crawling our way.  Last winter is one we won’t soon forget—the season started out mild before temperatures plummeted with January’s polar vortex.  During the coldest stretch, our coping strategy might have involved layers of blankets and reruns on Netflix, but what about the bugs? Questions regarding the winter impacts on insects have been some of the commonest at the UW Insect Diagnostic Lab this year.  There will undoubtedly be some impacts of this year’s polar vortex, although many insect species are well-equipped to deal with the cold.  Before we know it, overwintering insects will become active again in the Midwest and many species will simply shrug off the polar vortex as if it hadn’t happened.  For insects that didn’t fare as well in the cold, high reproductive capacities will likely allow their numbers to bounce back relatively quickly.

Thus, 2019 isn’t going to be insect-free by any means and intuitively this makes sense.  We know that every year insects make it through the winter months and become active as temperatures creep up in spring.  Looking at an evolutionary time scale, this year’s cold snap wasn’t the first time that the species in our area have encountered frigid temperatures before, and many creatures are adapted to survive surprisingly cold conditions.   We might have chosen to block it out of memory, but the Midwest experienced a very similar situation a mere five years ago.  Weather patterns in January of 2014 saw temperatures dip to -20˚F and colder in some spots of the Midwest.  The following summer, we still had plenty of insect activity in the region.

Thermometer from a cold and crisp Wisconsin morning. Photo credit: PJ Liesch, UW Insect Diagnostic Lab

Since we don’t see insects bundling up with tiny mittens and scarves, how do they make it through the winter?  It turns out that insects and other arthropods have a number of strategies to help them survive.  For starters, insects typically have a particular life stage (e.g., egg or pupa) that is more tolerant of adverse environmental conditions, such as freezing or desiccation.  Passing through the winter as a more resilient life stage is a good starting point.

Some of the other strategies are surprisingly similar to humans.  Just like snowbirds heading to warmer states for the winter, certain insects like monarch butterflies and green darner dragonflies migrate southward to avoid the coldest temperatures.  Our official state insect (the honey bee) doesn’t migrate, and instead chooses to remain active.  Honey bee colonies shiver together as an insect version of central heating to keep the inside of their hive a constant temperature.  Other insects simply seek shelter and overwinter in protected locations to avoid the worst of the cold.  Insects like the multicolored Asian lady beetle, boxelder bugs, and the invasive brown marmorated stink bug are fond of sneaking into man-made structures to spend the winter.  If insulation and central heating make homes warm enough for us, it’s plenty warm to prevent insects from freezing.  In more natural settings, such insects might end up sheltering in rock piles or beneath the loose bark of a dead tree.  Those locations might not be as toasty as a house, but they can still provide adequate respite from the cold—meaning that insects using this strategy should have been well protected from this year’s cold spell.  Similarly, many insects and other arthropods spend the winter below ground or on the surface of the ground amongst a layer of insulating leaf litter.  In addition, many parts of Wisconsin had a solid covering of snow by the time the polar vortex arrived, so creatures such as ticks had a thick layer of insulation from the coldest of the cold.

Another strategy utilized by insects is the production of natural antifreeze compounds (specific alcohols or proteins) which serve as cryoprotectants to help prevent freezing within their bodies.  We know that a cup of water will turn to ice at 32˚F, but dissolve salts or other substances in that same water and it will require colder temperatures to freeze it.  Insects producing high concentrations of these cryoprotectants can remains unfrozen at surprisingly low temperatures, similar to a bottle of high-proof spirits kept in a freezer.  Taking it even further, the common black and brown woolly bear caterpillars seem to embrace the cold and actually allow ice to gradually form within their bodies.  This may sound like a fatal mistake, but by regulating the formation of ice crystals on their own terms, woolly bear caterpillars are able to control where ice formation occurs and limit it to specific areas of their bodies to prevent damage.  If the same caterpillars were unprepared and froze rapidly, their cells might burst like a can of soda put into a freezer.

The ubiquitous woolly bear caterpillar (Pyrrharctia isabella) is well adapted to winter conditions. Photo credit: Dave Govoni via Flickr.

And then the ash borer
The insect I’ve gotten the most questions about lately has been the emerald ash borer.  While not native to our area, this invasive pest comes from similar latitudes of eastern Asia and the cold-hardy larvae are fortified with cryoprotectants as they spend the winter beneath the bark of ash trees.  These natural antifreeze compounds have their limitations though, and just like sidewalk salt failing to melt ice on a really cold day, the cryoprotectants only work down to certain temperatures before freezing (and death) occurs.  For emerald ash borer, the point at which freezing spontaneously begins to occur (the supercooling point) is when temperatures dip into the range of -13˚F to -23˚F.  This year’s polar vortex did see temperatures fall into and below that range, which would have killed plenty of emerald ash borer larvae, although the insulating effects of the tree bark likely provided some buffering.

The pale end of a surviving emerald ash borer larva sticking out from its tunnel. When larvae are killed by freezing, they typically become discolored. This sample came from the Milwaukee area in early March, 2019. Photo credit: PJ Liesch, UW Insect Diagnostic Lab

Emerald ash borer populations will almost certainly take a hit from this year’s polar vortex, but it’s not going to be a knockout blow.  Give it some time and the reproductive capacity of this invasive species will allow populations to rebound.  The news reports of cold-induced EAB mortality in early February might have been encouraging, but scientific models from the US Forest Service suggest that to really knock down EAB in the long run, we’d have to experience arctic blasts on a regular basis—news that many Midwesterners aren’t likely to receive warmly.


Further Reading: For a great read on how wildlife survive the winter, check out Bernd Heinrich’s Winter World

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

2018’s Top Trends from the Diagnostic Lab (Part 1)

Each year the University of Wisconsin’s Insect Diagnostic Lab receives thousands of arthropod samples and reports from around the state and region, providing a unique perspective into insect and arthropod trends in Wisconsin and beyond.  This post is the first half of a series counting down the top arthropod trends in our area last year.  The second part will be posted in early February and can be found here.


10) Dagger and Tussock Moths:
A few species of fuzzy caterpillars were surprisingly abundant last year and there’s a good chance you might have bumped into these in your own neighborhood.  Two similar-looking yellowish species, the American dagger moth and the white-marked tussock moth, were extremely common around Wisconsin and were two of the most widely reported caterpillars last summer. Another tussock moth associated with milkweed was also surprisingly common in 2018. With many Wisconsinites growing milkweed to attract monarch butterflies, the black and orange caterpillars of the milkweed tussock moth were also noted in abundance around the state last year.

Fuzzy black and orange Caterpillar of the milkweed tussock moth (Euchaetes egle)
Caterpillar of the milkweed tussock moth (Euchaetes egle). Photo Credit: Katja Schulz via Wikipedia

9) Fungus Gnats:
Pick any spot on a Wisconsin map and 2018 was most likely a soggy year. Understandably, rain encourages insects and other creatures that thrive under damp conditions. Last year’s rains created great conditions for fungus gnats, which became quite abundant by late summer. While fungus gnats are harmless to people and pets, they can be an annoyance if present in high numbers. Fungus gnats thrive in damp organic materials, meaning that rich soil, compost piles, and decaying plants can produce masses of these tiny, dark-colored flies. The larvae of these insects can also be common in the soil of houseplants.  As Wisconsinites brought their favorite potted plants indoors in autumn to avoid approaching frosts, reports of indoor fungus gnats were common.

Small dark coloured gnats captured on a yellow sticky card trap
Tiny (2mm long) fungus gnat adults captured on a sticky card trap near indoor plants in fall of 2018. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab

8) Purple Carrot Seed Moth:
With several new, non-native insects showing up in Wisconsin every year, the impacts of each species can vary significantly. Some exotics, like the emerald ash borer make massive waves, while others cause merely a ripple. The impacts of one of our newest invasive insects, the purple carrot seed moth (Depressaria depressana), are not yet fully known. This European species was spotted in Wisconsin for the first time last summer and the tiny caterpillars love to feed on the flowers (umbels) of plants from the carrot family. Below-ground plant structures (e.g., the taproots of carrots) aren’t impacted, but notable damage to herbs like dill, fennel, and coriander can occur. As a result, this pest may be a concern for seed producers, commercial herb growers, or home gardeners with a fondness for dill and related herbs. The purple carrot seed moth has been reported in 8 Wisconsin counties thus far [Brown, Columbia, Dodge, Kewaunee, Milwaukee, Racine, Sheboygan and Washington Counties], so new county-level reports are encouraged at the UW Insect Diagnostic Lab.

Tiny (<1/4" long) spotted caterpillar of the purple carrot seed moth on dill.
Caterpillar of the purple carrot seed moth. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab

7) Odorous House Ants
Imagine the stereotypical black ants zeroing in on sugary foods at a picnic and you’d have a fitting profile of the odorous house ant (Tapinoma sessile). Of the 100+ ant species in the Midwest, the odorous house ant stood out in spring and early summer last year with its sheer abundance. The UW Insect Diagnostic Lab was flooded with calls about these sugar-loving ants during 2018’s rainy spring, especially when these ants wandered indoors. The spring rains may have forced the ants from waterlogged colonies to seek out higher-and-drier locations, making odorous house ants the most commonly reported ant at the diagnostic lab last spring.

SMall black ant—an odorous house ant worker
Odorous House Ant (Tapinoma sessile) worker. Photo Credit: JJ Harrison via Wikipedia

6) Stink Bugs:
While the Midwest is home to over 50 species of stink bugs, one particular species—the invasive brown marmorated stink bug—stands out to give the rest a particularly bad reputation. If you live in a part of the state with the brown marmorated stink bug, you may have already encountered this species. With its habit of sneaking indoors in the fall, this insect replaced boxelder bugs in some areas as the top home-invading nuisance pest of 2018. This Asian species has made the diagnostic lab’s Top 10 list for several years now and unfortunately doesn’t show any signs of slowing down. In 2018 alone, BMSB was detected in 8 new Wisconsin counties, which hints at potential damage to fruit and other crops in those areas in the coming years.

Adult brown marmorated stink bug
Adult brown marmorated stink bug. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab

To see the rest of Wisconsin’s top arthropod trends of 2018, check out part 2, available here in early February.

2018 Update: Brown Marmorated Stink Bug in Wisconsin

Author’s Note: Original post updated in January, 2019 due to a confirmed report in Waupaca Co. and suspected report in Oneida Co.


One of the most concerning invasive insects to appear in Wisconsin in the last decade is the brown marmorated stink bug (Halyomorpha halys).  This Asian species delivers a double-whammy of not only damaging crops and other plants, but also being a significant nuisance when it sneaks into buildings in the fall. Since its initial detection in the state in 2010, populations of this insect have built up slowly but steadily. 

Brown marmorated stink bug adult on the side of a building in fall. This is becoming a common site in some parts of the Midwest. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab.

What’s the current status of BMSB in Wisconsin?

As of late 2018, 28 counties have confirmed reports of the brown marmorated stink bug and a handful of other countries have suspected sightings.  This insect has a strong foothold in the state and was confirmed in eight new counties in 2018 alone—Eau Claire, Jackson, La Crosse, Marquette, Monroe, Richland, Trempealeau, and Waupaca counties. 

Distribution of the brown marmorated stink bug in Wisconsin—updated January 4th, 2019
Distribution of the brown marmorated stink bug in Wisconsin—updated January 4th, 2019. BMSB has been confirmed in 28 counties. Map Credit: PJ Liesch, UW Insect Diagnostic Lab.

Two core areas currently stand out for brown marmorated stink bug activity in Wisconsin: the Highway 41 corridor from Fond du Lac up to Green Bay and southern Wisconsin from Dane and Rock Counties east to the Milwaukee metro area.  These two areas have the longest history of BMSB in the state and account for the majority of reports thus far. 

Much of the state has yet to encounter this insect or truly experience its impacts.  When the brown marmorated stink bug is first detected in an area, there’s a proverbial “calm before the storm”.   The pattern observed in the state thus far has been a few “quiet” years where low initial populations of this insect result in only a few sightings annually.  However, after a few years in a given area, BMSB populations build up to the point where nuisance problems around structures are noted and reports of potential plant damage begin to trickle in.

What’s the Outlook for BMSB?

Unfortunately, Wisconsin has yet to see the full impact of this invasive insect.  Observations over the last few years have found that BMSB is able to survive our winters and reproduce in the state, so this adaptable pest will most likely continue to build its numbers in the coming years. 

Over time, the brown marmorated stink bug is likely to emerge as one of the top structure-invading pests in the state alongside the likes of boxelder bugs and multicolored Asian lady beetles.  In the eastern US, where BMSB has been established for over a decade in spots, problems can be significant.  In some cases these malodorous insects have been documented invading homes by the tens of thousands

Several brown marmorated stink bug juveniles on a dogwood shrub. Ornamental trees/shrubs, vegetables, and fruit crops can all be attacked by this insect. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab.

While widespread crop damage has not yet been observed in Wisconsin, it may only be a matter of time as population of this insect continue to build in the state.  Agricultural problems have also been significant in the eastern US, giving us a glimpse into what could potentially happen in coming years.  For example, brown marmorated stink bug caused $37 million dollars in losses to apples in the mid-Atlantic states in 2010 alone.  

Having been detected in Portage County in 2017, brown marmorated stink bug may soon start to pose a threat to vegetable production in central Wisconsin.  Similarly, specimens confirmed from Door County in 2017 are forcing fruit growers in that part of the state to keep a close watch on their orchards and vineyards.  With the recent detection of BMSB in several western Wisconsin counties, we’ll likely see BMSB populations slowly build in that part of the state over the next few years as well. 

What should you do?

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.

Weathering the Emerald Storm: EAB in Wisconsin

Like a kid watching a summer thunderstorm slowly rolling in and wondering how long until the rumbles would be directly overhead, I’ve had a morbid fascination with watching the progression of the emerald ash borer in the Midwest for over a decade.  Although emerald ash borer wasn’t found in Wisconsin until 2008, my connection with EAB precedes that by a few years.  It turns out my first job as a budding entomologist was as a summer intern for UW-Extension looking for signs of the insect in the state during the summers of 2005 and 2006.  Fast forward twelve years and that storm is finally overhead, at least in my neck of the woods.  I knew such a time would come, but it really hits close to home when the sounds of chainsaws mark the final days of your neighborhood’s ash trees—at least the ones that aren’t being treated. 

EAB Detection and Quarantines as of May 19, 2017. Click for larger version. Image source: WI-DATCP.

At the time of writing, 42 counties in Wisconsin have been quarantined for EAB.  While the southeastern part of the state has already been hit hard (green on the map above), a large chunk of the state has not yet seen the emerald ash borer or has only seen light pressure (click the map above to see more details on this topic). Unfortunately, this means that the emerald storm will only be getting worse over the coming years.  Along these lines, when EAB first arrived in Wisconsin, spread was slow and the annual number of new community-level detections was small.  However, as the populations of this insect have built up in the state, the number of new detections has increased dramatically as illustrated below:

Chart created using data from WI-DATCP on May 22, 2017. Click for a larger version.

Unfortunately, the outlook for the Midwest’s ash trees doesn’t look good and we’ll still be dealing with this insect for years to come.  Ironically, this isn’t the first time that we’ve watched a scenario like this play out.  As the baby boomer generation grew up, they watched as elms were devastated by the likes of Dutch elm disease.  As with emerald ash borer, Dutch elm disease had significant impacts on forested and urban areas and led to irreversible changes in the landscape around us.

With all this Doom-and-Gloom, is there a light at the end of the tunnel?
Possibly—but it may be a ways off.  For the time being, there are insecticide treatments available that can maintain the health of ash trees, although treatments are costly and are only feasible for relatively small numbers of trees.  Biological control is being explored as a potential way to control EAB populations, although results have been limited thus far.  However, with any biological control program, it can take years to work the kinks out of the system and see results.

A long-term plan may be to develop varieties of ash trees that are resistant to attack by the emerald ash borer.  In several locations in Ohio and Michigan, scientists have found a small percentage of “lingering” ash trees that have survived the initial onslaught of EAB and are monitoring those trees over time for continued survival and genetic traits that may help stave off infestations.  Interestingly, one particular species of ash (blue ash, Fraxinus quadrangulata) may hold important clues for long-term ash survival.  In some spots in Michigan, >60% of blue ash trees have survived in areas attacked by emerald ash borer.  While tree breeding programs may ultimately develop a resistant ash variety, this is likely years away and for the time being we’ll have to face the emerald storm.

Larval tunnels of the emerald ash borer beneath the bark of an ash tree. This damage disrupts the flow of water and nutrients and ultimately kills the tree. Image source: PJ Liesch, UW Entomology.

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!

Free Couch? Think Twice About Bed Bugs

Right around this time of the year in Madison and other college towns across the country, a smorgasbord of furniture and other goods appear along the sidewalk as tenants are frantically moving in and out of apartments. For historical reasons related to the need to register for classes in-person at UW-Madison, many of the leases end and begin in Madison around August 14th-15th each year, leading to an abundance of items on the curb free for the taking.   This is such a well-known and easily observable occurrence around Madison, that some have even affectionately referred to it as “Hippie Christmas”.

Free Mattress_opt
One of the many free items showing up around college towns these days. Photo Credit: PJ Liesch, UW-Entomology.

As the old saying goes, “one man’s trash is another man’s treasure” and this certainly could be the case with free things on the curb. That free couch along the sidewalk might look like the perfect addition to that larger apartment, and it can be hard to beat the price of that curbside armchair. However, there’s the real possibility of unwanted hitchhikers: bed bugs. While I’m all for reducing waste, reusing items, and recycling, the concern about bed bugs should not be overlooked.

Until the mid 1900’s, bed bugs (Cimex lectularius), been a common pest around the world. With the invention of synthetic insecticides around the time of World War II, these insects had nearly been wiped out. Given time, bed bug populations developed resistance to some of those insecticides. The insecticide resistance coupled with the rise of international travel and the bed bug’s stealthy stowaway tactics, meant that it was only a matter of time before they came roaring back onto the stage. That very phenomenon has happened in the past two decades, and bed bugs can now be found in every US state, and in a wide variety of situations––from student apartments to five star hotels. When bed bugs are detected, they can be eliminated with diligent tactics, although the task can be challenging and is best left to pest control professionals. Costs to eliminate bed bugs can easily be $1,000 or more.

Adult bed bug. Photo Credit: Gary Alpert, Harvard University, Bugwood.org
Adult bed bug. Photo Credit: Gary Alpert, Harvard University, Bugwood.org

Absolutely need to have that nightstand from the curb? A few steps can help prevent issues. The first is to simply know how to look for bed bugs and their telltale signs. Many folks seem to believe that bed bugs are too small to be seen with the naked eye, but this is far from reality. It turns out that adult bed bugs (image above) are roughly the same size, color, and shape as a small apple seed. Juveniles will have the same general shape, but will be smaller. Very tiny whitish eggs (~1mm long) and black spots (from digested blood) on furniture are other classic signs of bed bugs. [A useful guide to identify bed bugs and their signs can be found here].

Before bringing any item in from the curb, examining it thoroughly for any signs of bed bugs is well worth the effort in the long run.  Objects with a simple design (ex. a nightstand with few grooves for bed bugs to hide in) are easier to inspect than large upholstered furniture and mattresses.  For larger, hard to inspect items, it may not be worth the risk to grab such items.  For small items, one easy step is to place them into a large Ziploc bag and put them in the freezer for 7-10 days as a precaution. Bed bugs, or any other insects present in such an item would freeze during that time.

Bed Bug Signs_opt
Classic bed bug signs: black spots from digested blood and whitish eggs (~1mm long). Photo Credit: PJ Liesch, UW-Entomology.

What if you’ve moved into a new apartment and suspect it has bed bugs? Getting a suspected bed bug specimen properly identified is a crucial step. It turns out that there are a number of nearly identical species that can only be told apart under the microscope. These related species are associated with bats and birds; they don’t pose the same headaches as bed bugs and are controlled differently. If you’ve confirmed that bed bugs are present in your apartment, starting a conversation with your landlord is an important step; ignoring the situation is about the worst thing that could be done in such as case. Overall, it’s much easier for a pest control company to come in and eliminate a small bed bug infestation than a large one. This is especially true of large apartment and condo complexes, where bed bugs can spread from unit-to-unit over time, making control much more difficult. In addition, if you happen to be moving out of an apartment that has or might have bed bugs, it’s best to mark any items being discarded with spray paint so that others looking for furniture will know not to bring those items home with them.

For bed bug questions in rental situations and many other tenant-related topics, the Tenant Resource Center of Wisconsin offers assistance.  Safe moving and keep an eye out for bed bugs!

 

Is This a Kissing Bug?

Kissing” and “bugs”—two words you wouldn’t expect to be put together in the same sentence have been strung together rather frequently in the news lately.  No, this isn’t some poorly understood internet phenomenon amongst the youth of the country.  Rather, when you hear about “kissing bugs”, we’re really talking about a group of blood-feeding assassin bugs (Family Reduviidae, Triatoma species).

So what’s the story behind these insects and why the hype?
Kissing bugs are similar to bed bugs as they both feed on the blood of vertebrate hosts.  However, unlike bed bugs which have anthropophilic habits, kissing bugs are typically associated with animal nests in wooded areas.  Kissing bugs don’t go out of their way to sneak indoors, although if they do happen to wander in they can be attracted to the heat and carbon dioxide of a sleeping human.  When human bites do occur, it can often be on the exposed, softer skin of the face, hence the nickname of “kissing bugs”.  The biggest concern with kissing bugs is that under the right conditions they can serve as a vector of American trypanosomiasis (aka Chagas Disease), a serious disease that can lurk in the body and ultimately affect the heart and other organs.

What does the kissing bug story have to do with Wisconsin and the Great Lakes region?
In brief: not a whole lot.  While there are nearly a dozen species of kissing bugs in the western hemisphere, these insects are primarily found in rural Central and South America.  I recently spent some time amongst the Wisconsin Insect Research Collection’s  8 million+ specimens, and found no verified cases of kissing bugs in Wisconsin.  Technically, these insects have been found in some of the southern states, although they tend to be quite rare in the US and there isn’t any evidence to suggest that they’re expanding their range or increasing their numbers.  Unless you’ll be spending an extended amount of time in Central or South America, the threat posed by kissing bugs and Chagas disease is basically non-existent.  Overall, the hype about kissing bugs is more bark than. . .bite.

Think you’ve found a kissing bug in Wisconsin (or elsewhere)?
There are a few look-alikes that could potentially be confused with kissing bugs.  Boxelder bugs (Boisea trivittata) share the red and blackish coloration of certain kissing bugs, while the masked hunter assassin bug (Reduvius personatus) shares a similar body size and shape.  However, due to the slender body and similar “checkerboard-like” pattern around the abdomen , the insect getting confused the most with kissing bugs at the moment seems to be the western conifer seed bug (Leptoglossus occidentalis), which can be very common in Wisconsin and in many parts of the country.

Why the western conifer seed bug?  As described in an earlier post, western conifer seed bugs frequently try to sneak indoors in the fall to seek out a sheltered spot to spend the winter.  As a result, encounters with these harmless insects occur on a regular basis.  Want some peace of mind that the insect you’ve seen is a western conifer seed bug and not a kissing bug?  Check out this handy side-by-side guide comparing the eastern conenose kissing bug (Triatoma sanguisuga) with the western conifer seed bug:

Is this a kissing bug?
Distinguishing features of the Eastern Conenose Kissing Bug and Western Conifer Seed Bug; click for larger version. Photo Credit: PJ Liesch, UW-Entomology

Further reading:
Gwen Pearson recently covered the Kissing Bug story for Wired and included some excellent references.