Zika: An Issue in Wisconsin?

With mosquito season nearly upon us and all the headlines about Zika Virus in the news, a big question at the moment is: will Zika be an issue for us in Wisconsin?  Based on what’s known about the Zika Virus and the mosquitoes that transmit it, it’s unlikely that Zika will be a major issue for us in the state.  Certainly, we’ll get cases of Zika in the state, but these will almost certainly be from individuals that have travelled to areas with active Zika infestations.  Overall, if we look at the bigger picture, a much bigger concern should be deer ticks and Lyme Disease, which affects thousands of Wisconsinites each year.

The Zika situation is an interesting one.  The Zika virus itself was first discovered in Africa in the 1940’s and has been found in parts of the eastern hemisphere for decades.  It wasn’t until very recently that it popped up the western hemisphere.  Because the Zika Virus is linked to a number of serious health issues, such as microcephaly in newborns, it certainly can pose significant health risks—hence the headlines and the concern.

However, the virus is only half of the story—the other half being the mosquito species (vectors) capable of transmitting the virus to humans.  Two mosquito species are associated with Zika virus and other viral diseases such as Chikungunya and Dengue: the Yellow Fever Mosquito (Aedes aegypti) and the Asian Tiger Mosquito (Aedes albopictus).  The good news for us in Wisconsin is that neither of these mosquito species are native to our area, and these species have never been found in the state (additional surveys are being conducted to look for them).  With that said, there may end up being some Zika cases in Wisconsin associated with travel to areas where Zika is widespread, but the absence of the two mosquito vectors responsible for transmission will greatly reduce the chance for transmission occurring within the state.

Estimated range of Aedes albopictus and Aedes aegypti in the United States, early 2016. Map source: Centers for Disease Control and Prevention.
Estimated range of the Asian Tiger Mosquito (Aedes albopictus) and the Yellow fever Mosquito (Aedes aegypti) in the United States, early 2016. Map source: Centers for Disease Control and Prevention.

While the Yellow Fever Mosquito and the Asian Tiger Mosquito don’t occur here, there still is reason to be vigilant about mosquitoes.  With as many as 60 or more different mosquito species in the state, there are a number of other mosquito-borne diseases that do occur in our area.  Our best example would be West Nile Virus transmitted by the Northern House Mosquito (Culex pipiens).  While West Nile cases can vary dramatically from year-to-year, we’ve historically had issues with West Nile in our area, and human deaths have occurred in the past.

When it comes to mosquitoes in general, there are several approaches to keeping yourself and your family members safe. Around the yard, one of the most important things is to reduce or eliminate standing water to help eliminate mosquito breeding sites.  Toys left out in a sandbox, old tires, clogged gutters, birdbaths with stagnant water and anything else that collects and holds water could be a potential breeding site for mosquitoes.  Using EPA approved repellents, such as DEET, Picaridin, or others when working or relaxing outdoors will offer protection from bites.  Lastly, wearing long sleeves, avoiding outdoor activities during prime mosquito feeding times (dawn/dusk), or simply staying indoors can also protect you from mosquitoes.

 

The Case of the Hitchhiking Bog Wasps

While most of the cases at the Insect Diagnostic Lab involve fairly common insects, I do also see my fair share of unusual cases each year. One of my favorites from 2015 involved a miniature “bog wasp” from the family Eucharitidae: Pseudochalcura gibbosa. Due to their small size, these tiny (~2 mm long) wasps would simply go unnoticed in most cases––that and the fact that you’d most likely have to be wandering around in a bog to find them. So how exactly did these tiny, easily-overlooked “bog wasps” end up being submitted to the Insect Diagnostic Lab?  Simple: a homeowner found several in a second story bedroom of their house. This simply didn’t make much sense, so I knew there must have been a deeper story at play. Whenever I get an unusual case like this in the diagnostic lab, I often have to track down additional pieces of the puzzle before things make sense.

Bog Wasp-Pseudochalcura gibbosa
The tiny, hump-backed wasp: Pseudochalcura gibbosa. Photo Credit: PJ Liesch, UW-Entomology.

In this case, this particular home was located near Rhinelander, Wisconsin, where there’s certainly an abundance of bogs. As part of their life cycle, the females of Pseudochalcura gibbosa lay eggs on Bog Labrador Tea (Ledum groenlandicum), a common shrubby plant in northern bogs. The eggs spend the winter on the plants and hatch the following spring. However, these wasps aren’t plant feeders, and their presence on Labrador Tea is temporary. What they’re really after are immature carpenter ants (Camponotus sp.) to feed on. After the eggs of Pseudochalcura gibbosa hatch, it’s thought that the wasp larvae hitch a ride on foraging carpenter ant workers back to their nest. Once they’ve dropped off their six-legged taxis in the ant nest, the tiny larvae of Pseudochalcura gibbosa behave much like a wood tick on a dog: they hang off of and feed on carpenter ant larvae and pupae. In some cases, dozens of small wasp larvae may be present on a single carpenter ant larva. Eventually the tiny wasps complete their development and leave the carpenter ant nest to head back to the bog.

Having identified the wasps as Pseudochalcura gibbosa, I was suspicious that a carpenter ant nest was also present in the home and simply hadn’t been found yet. After some detective work, the homeowner eventually confirmed the presence of carpenter ants in the house. With that final piece of the puzzle I had my explanation for how the wasps had hitchhiked from a nearby bog to an upper story bedroom: it’s was all the ants!

Wisconsin’s Top Insect Trends of 2015 (#5 – #1)

In this post, we’re continuing to count-down 2015’s top insect trends in the state.  This is the final post in a three part series.  Part I (2015’s diagnostic lab statistics) can be found here and Part II (Top Insect Trends Numbers 10-6) can be found here.

5) Pollinators
With all the headlines about bees, it’s not surprising to see pollinators in the top insect stories again in 2015.  Similar to other years in the recent past, honeybees and other pollinators have been facing declines.  Unfortunately, Wisconsin saw some of the highest honeybee losses in the country, with over 60% colony loss during the 2014-2015 period.  Some good news over the past year has been the development and release of pollinator protection plans.  A federal pollinator protection plan was released in May with the goals of reducing honeybee losses, increasing the population of Monarch butterflies, and increasing pollinator habitat.  In addition, a Wisconsin pollinator protection plan was announced in 2015, and was just released in January of 2016.   Due to the recent declines and their importance to agriculture in the state and nation, pollinators will continue to be in the spotlight in the future.

A ground nesting bee (Colletes sp.) near the stump of the former President's Oak on the UW-Madison campus. Photo Credit: PJ Liesch
A ground nesting bee near the stump of the former President’s Oak on the UW-Madison campus. Photo Credit: PJ Liesch

4) Spring caterpillars
An unexpected insect trend in the spring of 2015 was the surprising abundance of a number of caterpillar species feeding on plants in the landscape.  Caterpillar species, such as the humped green fruitworm, speckled green fruitworm, eastern tent caterpillar, forest tent caterpillar, gypsy moth caterpillar, and the euonymous caterpillar are typically present to some extent, although their numbers have been low the past few years.  For a number of potential reasons, these species had a great spring and during a period in May and June, caterpillars made up roughly 30% of the cases coming in to the diagnostic lab.  Weather patterns (i.e., rainy weather) and natural predators/parasites/diseases can have significant impacts on caterpillar populations each year, so it’ll be interesting to see if we’re faced with a plethora of caterpillars again in 2016.  Additional details of this story were featured in a blog post last June.

3) Viburnum Leaf Beetle
In terms of a new emerging pest with the potential to impact a commonly planted landscape shrub, Viburnum Leaf Beetle is near the top of the list.  As of late 2014, we only knew of a single infested viburnum bush in northern Milwaukee County, which raised the question: is the infestation small enough to contain and/or eradicate?  Some ground truthing this past spring identified many new infestations in SE Wisconsin, in many cases miles from the original site.  At the moment, the viburnum leaf beetle seems to be centered around the four county area where Milwaukee, Waukesha, Washington, and Ozaukee counties meet.  While this insect only feeds on viburnums (and related plants like Arrowwood), the damage can be significant.  It may be some time before this pest spreads elsewhere in the state, but if you have viburnum plants in your yard in SE Wisconsin, be weary!  Additional details of this case were featured in a post last June.

VLB Damage
“Skeletonizing” feeding damage from adult viburnum leaf beetles. Photo courtesy of Paul Weston, Cornell University, Bugwood.org

2) Brown Marmorated Stink Bug
Populations of the invasive Brown Marmorated Stink Bug increased dramatically in 2015 and this insect takes the overall #2 spot in this list (up from #8 last year).  This invasive species was first spotted in the state in 2010, and each year a handful of lone adults have been found in Wisconsin.  In the fall of 2015, we had more sightings of BMSB (30+), than in the past 5 years combined! (Spoiler: this trend has continued into early 2016)  At this point, the “hot spots” in the state are: Dane County, the greater Milwaukee area, and the Fox River Valley.  In addition to being an indoor nuisance pest, BMSB can also feed on and damage a wide variety of plants in home gardens, agricultural fields and orchards.  In other places in the country, the first reports of plant damage have typically been noted ~3-5 years after the initial detection of this species.  With that said, 2016 could be the year that BMSB really takes off and starts wreaking havoc for gardeners and agricultural growers alike.  Additional details of this case can be found in this post from last October.

1) Magnolia Scale
While scale insects have already been mentioned in the “sucking insects” section (#9 on the list), one species in particular, the Magnolia scale (Neolecanium cornuparvum), seemed to stand out amongst all other insects in 2015.  This species is often present in low numbers in the state, but the conditions must have been perfect for their populations to explode last year.  During the months of June and July, reports of Magnolia scale were coming in on almost a daily basis.  Being one of the unusual scale insects, Magnolia scale adults look more like a fungus than an insect (note the whitish blobs in the image below).  Not only did this bizarre looking species pummel Magnolia shrubs and trees in many parts of the state, but the honeydew produced by these insects rained down below, attracting ants and yellowjackets and leading to the growth of unsightly black sooty mold.  A number of predators, parasites, and diseases typically keep Magnolia scale in check, but with the extremely high infestations noted last year, it’s likely that we’ll continue to see some Magnolia scale activity into 2016.  If you experienced magnolia scales first hand, there’s a helpful factsheet available here.

Magnolia twig coated with whitish, fuzzy magnolia scale adults.

Wisconsin’s Top Insect Trends of 2015 (#10 – #6)

What were Wisconsin’s top insect trends of 2015?  In this post, we’ll look at the first half of our count-down.  

This is the second post in a three part series.  The first post of the series (2015’s diagnostic lab statistics) can be found here.

10) Mosquitoes and ticks:
Like most years, Wisconsin had a pretty good mosquito season.  Overall, we were close to the average rainfall mark during much of the year, which meant the typical batch of mosquitoes starting after Memorial Day.  In many parts of the state, mosquitoes were prevalent throughout June, July, and August.  However, this is Wisconsin after all, and mosquitoes seem to be one pillar of summer culture along with beer, cookouts, and fishing.  The silver lining of the mosquito story is the fact that West Nile Cases were low for the year, with only four confirmed human cases reported in the state in 2015.

Deer Tick
Adult female deer tick. These ticks can now be found throughout the state and roughly 40% of adults are carrying the microorganism responsible for Lyme Disease. Photo credit: Scott Bauer, USDA Agricultural Research Service, Bugwood.org

While there wasn’t anything out of the ordinary with the mosquitoes last year, ticks seemed to have a particularly good year in the state.  Deer ticks, which can vector Lyme disease can be found essentially statewide.  From the standpoint of an emerging health threat, deer tick populations have exploded in the past few decades (our first deer tick wasn’t found in the state until the 1960’s).  A recent nation-wide study found that deer ticks were found in nearly half of the counties in the U.S.  One of the more alarming trends is urban encroachment.  Historically, ticks seemed to be the type of creature you’d pick up if you were out hunting or hiking through the woods.  In the recent past, we’ve noticed an increase of ticks found in more urban environments, such as parks and backyards.  With roughly 40% of the adult ticks in Wisconsin carrying the microorganism responsible for Lyme Disease, this is an issue that will continue to exist in the state for years to come.

9) “Sucking Insects”
A certain group of insects (the Order Hemiptera) are sometimes known as the “sucking insects” because they possess tube-like mouthparts which are used by many species use to drink fluids from plants.  Two of the members of this group, the aphids and the scale insects had a great year in 2015.  When these insects feed on plants, a common sign is the presence of sticky, sugary honeydew, which attracts ants and yellowjackets, and can result in the growth of black sooty mold.  Aphids and scale insects are common and typically present in low numbers, but the conditions must have been just right for their populations to thrive in 2015.  As a result, there were many reports throughout the state of honeydew “raining” down from trees and shrubs onto vehicles, decks, outdoor furniture, and people below.  If you felt “rain” on a sunny day last summer, the actual cause may have been honeydew dripping down from aphids or scales in the trees above!

Lecanium Scale
Lecanium scales producing sticky honeydew (clear droplets).  Photo credit: Ronald S. Kelley, Vermont Department of Forests, Parks and Recreation, Bugwood.org

 

8) Long Lost Pests: Japanese Beetle and Gypsy Moth
Two of our best-known landscape pests, the Japanese Beetle and the Gypsy Moth had been very quiet in 2014, but resurfaced last year.  Japanese beetles had been low across the state in 2014, likely due to the brutal winter of 2013-14 killing many of the soil-dwelling grubs.  While we did see an increase in beetle activity in 2015 compared to 2014, their numbers still seemed low compared to the long term average.  However, with a milder el Niño winter, it’s possible that we could see increased winter survival and higher Japanese beetle populations in 2016.

Japanese Beetle
The infamous Japanese Beetle. Photo credit: David Cappaert, Michigan State University, Bugwood.org

Gypsy Moth populations have been low the past few years in Wisconsin.  Damp spring conditions can result in a fungal disease killing many of the caterpillars, which likely helped lessen populations in the recent past.  It’s also not unusual for some long-term cyclic patterns to be involved with insect populations.  For a number of potential reasons, Gypsy Moth populations seemed to rebound a bit in 2015, and many reports of sightings and damage came in to the diagnostic lab, particularly from the south central portion of the state (Dane, Rock, Walworth Counties).  Because Gypsy Moth can be a destructive defoliator of hardwood trees, it’ll be good to keep an eye out for this one in 2016 to see if the populations continue to climb.

7) Emerald Ash Borer
This is our most destructive forest pest in the state, and unfortunately, there doesn’t seem to be anything capable of completely stopping this pest.  While we didn’t see many additional counties added to the quarantine map in 2015, there were many municipalities that detected EAB for the first time.  At the moment, 39 of the 72 Wisconsin counties are quarantined for EAB and this number will continue to increase over time.  Like Dutch Elm Disease in the past, Emerald Ash Borer is changing and will continue to change the appearance of our urban forests and woodlands for years to come.

6) Spotted Wing Drosophila
This invasive pest first showed up in the state in 2010, and became a significant fruit pest almost immediately.  Since its introduction, SWD has spread widely and can be found in most counties in Wisconsin.  Very similar to 2014, SWD was detected in dozens of counties across the state.  SWD can attack a wide variety of fruit, but due to the fact that this insect doesn’t seem to become active until July, the late-season raspberry and blackberry crops are hit the hardest.  Luckily Wisconsin’s famous cranberry crop does not seem to be favored by this invasive pest.

Up Next, Part III:  Wisconsin’s Top Insect Trends of 2015 (Numbers 5-1) 

State of the Lab Address 2015

What’s been “crawling” in the UW-Madison Insect Diagnostic Lab this past year?   Find out in this three part series.

The State of the IDL in 2015

Caseload
While it wasn’t exceptionally “buggy” in Wisconsin this past year, 2015 ended up seeing the highest annual caseload ever handled by the UW-Madison Insect Diagnostic Lab. The previous annual caseload record belonged to 2013, with 2,207 specimens. In 2015, the lab identified a whopping 2,423 specimens from 71 of the 72 Wisconsin counties. The vast majority of cases, (>94%; 2,287 specimens) originated from within the state of Wisconsin, 93 samples (digital images) came from other U.S. states, and 43 international samples (digital images) were handled by the IDL in 2015*. As expected, the bulk of the submissions came during the warmer months when insects are most active as illustrated below:

2015 IDL Caseload
Click for larger view

 

Sample Submission
Overall, roughly half of the samples processed by the lab in 2015 consisted of digital images, which is similar to other recent years; the remainder of the cases involved physical specimens or verbal descriptions of the insects.  Approximately half of the processed samples were submitted by the general public, over a quarter came from UW-Extension county agents/support staff, and smaller quantities came in from pest control professionals, agricultural producers and consultants, members of the green industry (lawn care, arborists, nursery), medical and public health professionals, and colleagues in academia and government agencies such as the Wisconsin Department of Natural Resources and Wisconsin Department of Agriculture Trade and Consumer Protection.

2015 Sample Submission by Group
Click for larger view

 

Sample Identity
In 2015, the Insect Diagnostic Lab’s database was upgraded to include real-time statistics on the identity of specimens submitted to the lab. Overall, >80% of the samples handled by the lab were Hexapods (insects and close relatives, such as springtails), >10% were arachnids (spiders, mites, ticks) and myriapods (centipedes and millipedes), and the remainder of the cases involved other animals (slugs, crustaceans, vertebrates, etc.) or other factors (plant disease, physiological plant stress, and non-living or unidentifiable specimens). Of the insect specimens processed in 2015, 21 different major insect groups (orders) were represented as shown in the chart below. Of these groups, 5 orders in particular made up 92% of the specimens handled by the IDL last year:

  • Coleoptera: beetles, such as Japanese beetles and carpet beetles
  • Hemiptera: “true Bugs”, such as aphids, and boxelder bugs
  • Hymenoptera: ants, bees, wasps, and yellowjackets
  • Lepidoptera: moths, butterflies, and their young (caterpillars)
  • Diptera: “true flies”, such as house flies and mosquitoes
2015 Samples by Taxa
Click for larger view

Interestingly, submissions can vary quite a bit throughout the year as illustrated by the prevalence of caterpillars seen this past spring as described in an earlier blog post.

Other Lab Activities
In addition to providing diagnostic services and pest management advice, another major function of the Insect Diagnostic Lab is to provide insect-related outreach for UW-Extension and the UW-Madison Entomology Department. To that end, IDL staff delivered 105 presentations at workshops, field days, seminar series, and other events and participated in dozens of Extension and outreach events throughout Wisconsin in 2015 (State Fair, Garden Expo, summer children’s programs, etc.). IDL staff also conducted 36 radio, TV, and newspaper interviews in 2015, including 7 (1.5 hour) episodes on Wisconsin Public Radio’s “The Larry Meiller Show”. Eight Extension factsheets and other publications were authored or co-authored by IDL staff in 2015 and the Insect Diagnostic Lab and associated “Insect ID” website were viewed over 400,000 times in 2015.

Up Next, Part II: Wisconsin’s Top Insect Trends of 2015 (Numbers 10-6)

* In case you’re curious, international cases in 2015 came from 11 different countries on four continents: Mexico, Costa Rica, the United Kingdom, Italy, Greece, Nigeria, Zambia, India, Bhutan, the Philippines, and Japan.

Was that 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:

Kissing Bug ID
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.

Be Thankful for Insects

As we’re sitting down for the Thanksgiving feast, there’s one thing we should all be thankful for, whether we realize it or not: insects.  It turns out that insects are involved one way or another with many of the foods we’ll be stuffing ourselves with tomorrow.  Without insects, the dinner table would have a drastically different appearance.

Think about the ubiquitous pre-dinner veggie platter at the family get-together.  If you already have seeds of carrots, celery, broccoli, and cauliflower, you can technically grow a batch of these crops just fine.  But with many vegetables, insect pollinators help produce that next batch of seeds.  Then there’s the cheese and cracker appetizer plate.  Being made from wheat (a wind pollinated plant), crackers technically don’t require insects to be produced.  You might also think that cheese (being a dairy product) is also unaffected by insects.  However, insects play a role in the production of alfalfa, which is a common food source for cows.  Without alfalfa, cheese, butter, and other dairy products would be harder to produce, and could be tough to find at the grocery store.  Oh, and without insects as pollinators, we wouldn’t have the almonds on the outside that smoked cheese log anymore.

Some of the items from the main course don’t rely on insects to make it to the table: turkey and potatoes.  Technically, wild turkeys can feed on insects as part of their diet, although they can feed on many other things as well.  If you’ve recently seen The Martian, you’ll remember astronaut Mark Whatney growing potatoes sans insects to survive, so those mashed potatoes would still make it to the table.  Bread and dinner rolls (from wind-pollinated wheat) would still be around.  We could also have certain vegetables that can self-pollinate without insects, such as lima beans (who doesn’t love a great big helping of lima beans…).  However, some big players on the dinner table rely on insects for pollination, including the many types of squash.  One of the most crucial Thanksgiving dishes, the cranberry sauce, wouldn’t be around as cranberries rely on bees for pollination.  It’d be a sad Thanksgiving if there were no cranberry sauce.

As we finish dinner and get ready to watch the Packers-Bears game, it’d be about that time for dessert and coffee to perk up. Unfortunately, that’s where some bad news comes in.  Without insect pollinators, we wouldn’t have pumpkins to make the traditional pumpkin pie, or some of the spices, like nutmeg, to flavor it.  The whipped cream to go on top?  Well that’s one of those dairy products that could be hard to come by in a world without alfalfa.  Maybe you don’t care for pumpkin pie and prefer apple, cherry or blueberry pie instead?  Those fruits all rely on insect pollinators as well.  More bread for dessert, anyone?  Maybe we’ll forget about dessert and go right for that coffee so we don’t fall asleep on the couch.  Just keep in mind that insects are also responsible for the pollination of coffee plants.

When it comes to Thanksgiving tomorrow, be thankful for family, friends, good health, and also the insects that helped put a lot of that great food on the table.

Conifer Seed Bugs

Since last week’s press release on the Brown Marmorated Stink Bug by the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) and my own blog post on this invasive pest, I’ve been getting many reports of this insect from Wisconsin residents.  It’s always great to get reports from the community as it helps us keep track of this invasive pest.

Brown Marmorated Stink Bug ID
Identifying features of the Brown Marmorated Stink Bug; click for larger version. Photo Credit: PJ Liesch, UW-Entomology

Interestingly, there have also been many cases of an insect that somewhat resembles BMSB: the Western Conifer Seed Bug.  Both insects try sneaking into buildings to look for shelter and possess “checkerboard” patterns at the back of the body.  However, when you have the insects side by side, they can be easily separated.  The western conifer seed bug is longer and more slender in appearance, has dull reddish and orange patches on the body, and has distinctly dilated hind legs (think “bell-bottoms”).  In addition, these insects possess a unique zig-zag (“lightning bolt”) pattern on each wing, which can easily be seen with the naked eye as illustrated in the ID guide below.

Western Conifer Seed Bug-ID Guide_opt
Distinguishing features of the Brown Marmorated Stink Bug and Western Conifer Seed Bug; click for larger version. Photo Credit: PJ Liesch, UW-Entomology

While the western conifer seed bug  can sneak into buildings in the fall, they tend to invade in relatively low numbers.  This species feeds on the seed cones of pines and other conifers, but doesn’t seem to cause much (if any) harm to the trees.  Overall, they can be a bit of a nuisance, but that’s about it, unlike BMSB, which can potentially damage many different types of plants.

Have western conifer seed bugs around the house and want to know more about their biology and management?  Check out this handy factsheet from UW-Extension.

Why Such a Stink About a Bug?

Every fall, residents throughout Wisconsin and many other parts of the country face an invasion by a number of insects: boxelder bugs, multicolored Asian lady beetles, western conifer seed bugs and cluster flies, to name a few.  With the coming frosts, these insects are simply trying to find a sheltered location to settle for the winter.  Out in nature, many of these insects would simply crawl into a rock pile or beneath the loose bark of a dead tree to overwinter.

MALB Overwintering_opt
Multicolored Asian Lady Beetles often spend the winter in sheltered spots, such as beneath the bark of dead trees. However, they can just as easily sneak into buildings. Photo Credit: PJ Liesch, UW-Entomology

But why rough it out in nature if there are perfectly good buildings to sneak in to?  Next time you’re cleaning the gutters, take a moment to peek around the outside of your house.  Small gaps in siding, soffit areas, around door and window frames, and cracks in the foundation are all potential spots for insects to sneak through.  And if they make it through?  Well, you could be in for some extended visitors. . .

In addition to the usual fall invaders, a relative newcomer starting to pop up in Wisconsin and other parts of the Midwest is the invasive Brown Marmorated Stink Bug (Halyomorpha halys).  Like the boxelder bugs and multicolored Asian lady beetles, brown marmorated stink bugs (BMSB) like to find their way indoors for the winter.  This Asian species was first detected in Wisconsin back in 2010 and for reasons we don’t fully understand, their numbers have been quite low the past few years.  As of late 2014, BMSB has been confirmed or suspected in 10 Wisconsin counties, with most of the reports coming out of the Madison and Milwaukee area.  A handful of sightings each year has been the pattern.

Unfortunately, we may be at the beginning of a shift in BMSB populations in the state.  In early 2015, there were at least 6 specimens found in Wisconsin by early March.  Despite the quiet summer, the sightings have started popping up again in late September and October of this year.  What’s more concerning is that we’re starting to see groups of these insects clustered together (previous sightings had consisted almost exclusively of lone individuals).

Not only are these unwanted houseguests a nuisance, but quite frankly, they smell bad.  True to their title of “stink bug”, brown marmorated stink bugs possess glands that can emit a pungent odor.  Some consider the odor to be coriander-like, while others  say it resembles musty gym socks.  Invasive species [check].  Nuisance invader [check].  Smells bad [check].  That’s all, right?  Unfortunately, not quite.  Just like a bad late-night infomercial: Wait! There’s more!

Bad Bug Checklist-Upload

It turns out that brown marmorated stink bug has the potential to be quite a nasty plant pest and rivals the Japanese beetle in the breadth of its palate.  Brown marmorated stink bug seems to feed on just about anything under the sun: field crops like corn and soybeans, vegetables like tomatoes and peppers, and even ornamental trees and shrubsFruits like apples and grapes can be hit especially hard.  In some cases, the mere presence of BMSB can be a problem: imagine being a vintner and having your batch of wine tainted by the presence of a few squished stink bugs!  In the eastern U.S. there are regular reports of agricultural problems and growers have to spray to control these insects.  We haven’t had any reports of plant damage in Wisconsin yet, but that could change over time if BMSB populations continue to climb.

So what can you do about brown marmorated stink bugs?  For starters, learning to tell them apart from our native stink bugs is relatively easy.  Look for the alternating “checkerboard” pattern along the back edge of these half-inch long insects and the two light bands on the otherwise brown antennae.

Brown Marmorated Stink Bug ID
Identifying features of the Brown Marmorated Stink Bug; click for larger version. Photo Credit: PJ Liesch, UW-Entomology

With relatively few sightings in Wisconsin at this point, we’re still trying to get a feel for where this insect is.  If you suspect that there may be brown marmorated stink bugs around your house, take a picture of the insect and email it to me at (pliesch@wisc.edu) for identification.  Another option is to collect a physical sample and mail them in to the Insect Diagnostic Lab for identification (instructions on how to submit samples can be found here).

If brown marmorated stink bugs or other fall invading insects are trying to get into your house, one of the best things to do is to inspect the outside of your home and physically seal up cracks and crevices where they’re trying to sneak in.  Once fall invaders are indoors, hauling out the hose attachment on the vacuum cleaner is often one of the best steps to remove them.

 

Yellowjacket Season

It happens every year in August and September: someone takes their lawnmower over a nest in the ground and really “stirs up the hornet’s nest”.  Shortly thereafter, I get a call regarding these black and yellow stinging “ground bees”.  Technically, these nests are neither the work of hornets nor bees, but rather yellowjackets. [There are actually ground-nesting bees, although they tend to be docile, solitary creatures; see this post from April].

Ground nesting Yellowjackets
Ground-nesting yellowjacket workers at the entrance of their nest. Photo Credit: Jeff Hahn, University of Minnesota

Yellowjackets are a type of wasp, related to paper wasps and bald-faced hornets—all of which can be abundant this time of the year.  In fact, wasps are one of the most common insects reported to the diagnostic lab in late summer each year.  Depending on the species, yellowjackets (Vespula species) can nest in pre-existing cavities in the ground, above ground, or in hollow voids (such as wall voids and soffit areas of roofs).  Bald-faced hornets (Dolichovespula maculata) are the larger cousins of our common yellowjackets, and can produce basketball-sized papier-mâché style nests that can often go unnoticed until the leaves fall off the trees in fall.  Paper wasps (Polistes species) are more slender in appearance than yellowjackets and build the open, umbrella-like nests that often hang from soffit areas.

Bald Faced Hornet Nest
Aerial, papier-mâché style nest of the bald-faced hornet.  If you click to see the enlarged version, you’ll notice the head of a lone worker peering out from the entrance of the nest. Photo Credit: Pat Malone, Trempealeau County UW-Extension

Yellowjackets, bald-faced hornets, and paper wasps are what we refer to as social wasps, meaning that they live and work together as a colony.  Each species varies in its particular traits (body size and coloration, nest location, colony size, etc.) and we have dozens of species in our area.  An interesting point about the biology of social wasps is that a queen starts her colony from scratch each spring and the colonies die out in the fall.  A small group of females designated to become queens the following year does make it through the winter in sheltered locations such as rotting logs.  The tiny colonies from spring build up in size throughout the summer, reaching their maximum size this time of the year.  This can give the impression that the insects appeared abruptly, when in reality, the colonies have been there and the wasp populations have built up rapidly over the past few weeks.

Paper Wasp Nest
Paper wasps on their open, “umbrella” style nest. Photo Credit: Jeff Hahn, University of Minnesota

Because the colonies die out in the fall, if a wasp nest is located in an infrequently visited back corner of your yard, simply waiting for a few hard frosts will ensure that the colony has met its demise.  If a colony is located in a spot where you’ll likely have run-ins, there are some reliable ways to eliminate them, but choosing the correct tool for the job can be critical!

To learn more about the biology of social wasps as well as how to manage wasp nests, check out this webpage: http://www.extension.umn.edu/garden/insects/find/wasp-and-bee-control/

 

Department of Entomology

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