Category Archives: IDL Highlights

Great Golden Digger Wasp: Another Asian Giant Hornet Look-Alike

With the media craze about “murder hornets” this past spring, I’ve seen a definite increase in reports of Asian giant hornet look-alikes at the UW Insect Diagnostic Lab this summer.  Many folks recognize the commonest look-alike in the Midwest, the eastern cicada killer (Sphecius speciosus), which becomes active in July around the time that their prey (cicadas) start emerging.  Another look-alike is one that you might not have bumped into before—the great golden digger wasp (Sphex ichneumoneus).  Similar to Asian giant hornets, great golden digger wasps are large and nest in the ground, which are reasons why they may be mistaken for the former.

If you haven’t spotted one before, great golden digger wasps can be a bit intimidating in appearance as they can easily be over an inch long.  However, their anatomy and appearance are quite different compared to Asian giant hornets.  Great golden digger wasps are mostly black with a rusty-reddish color at the base of the gaster (“abdomen”).  Their legs are the same reddish color and the black thorax and head possess fine golden setae or “hairs” (hence “golden” in their name).  In contrast, Asian giant hornets have distinctive black and yellow stripes on their gaster and a vibrant yellowish-orange head.  Great golden digger wasps belong to the “thread-waisted” wasp family (Family Sphecidae) and have a long, slender petiole (“waist”).  This isn’t as thin and narrow as the “waist” of the related black and yellow mud dauber (Sceliphron caementarium), but still is quite noticeable when viewed from the side.

Great golden digger wasp
Great golden digger wasp (Sphex ichneumoneus); note the slender petiole or “waist”. Photo credit: Judy Gallagher, via Wikipedia.

In terms of their biology, both Asian giant hornets and great golden digger wasps do nest in the ground, but the similarities end there.  The Asian giant hornet is really quite similar to our ground-nesting yellowjackets in terms of their nesting behavior.  These are social creatures which start nests from scratch in spring and build up in size over the course of the warmer months.  Colonies ultimately die out in fall except for the “new” queens which overwinter.  With a large colony of relatives to defend, social wasps can be defensive, especially when colonies are at peak size.

In contrast, great golden digger wasps are solitary ground nesters.  Without a large colony of relatives to defend, they’re usually non-aggressive and very unlikely to sting.  Stings are only likely if one were to pick one up bare-handed—in which case you might be asking for it!  Similar to cicada killer wasps, each female great golden digger wasps excavates small tunnels in sandy soil and provisions them with prey for their young to feed on.  In the case of the great golden digger wasp, prey consists of katydids, crickets, and relatives from the “grasshopper” group (Order Orthoptera).  Rather than kill outright, the females inject their prey with a paralytic “cocktail” to keep them alive and fresh for their young to feed on—what a way to go!  In addition to hunting katydids, adult great golden digger wasps visit flowers and can be beneficial pollinators.

Great golden digger wasp on flower
Great golden digger wasp (Sphex ichneumoneus) drinking nectar from a flower. Photo credit: Roy Niswanger, via Flickr.

Because they’re unlikely to sting humans, controlling great golden digger wasps is rarely justified and these magnificent creatures can simply be admired.  Ultimately, these wasps are strongly associated with sandy soil, so if you see them in your yard every year and would prefer to not have them around, modifying the landscaping may be a long-term option to dissuade them from an area.


Author’s note: As of August 2020, Asian giant hornets have not been found in Wisconsin or anywhere in the Midwest.  In North America, these insects are only known from far northwestern Washington state and nearby parts of British Columbia. 

See this earlier post for additional details on the Asian giant hornet.

Some Insects Don’t Understand Social Distancing

In the grand scheme of things, most insects (and spiders) are loners.  Perhaps they set a good example for us in 2020 with their social distancing.

Of course, insects have to find a mate to reproduce at some point in their lives*, but out of the 1 million+ described insect species, being truly “social” isn’t the norm.  There certainly are some well-known examples of insects that are eusociali.e., they live together as a colony.  Examples include ants, certain types of wasps (such as yellowjackets and paper wasps), some bees, termites, and a few other interesting examples.  However, there are many insects that are much more solitary in their habits.  If you think of our bees in the Great Lakes region, we have roughly 500 species.  Other than honey bees, bumble bees and a few others, the vast majority of these species are solitary creatures with each female doing her own thing.

Two herds of Cerastipsocus venosus barklice. Photo submitted to UW Insect Diagnostic Lab.

Interestingly, there’s a quirky insect that can be commonly encountered this time of the year and it missed the memo on social distancing.  I’m referring to an interesting species of barklouse (Order Psocodea): Cerastipsocus venosusBarklice are relatives of true lice (e.g., head lice and pubic lice) but they’re really quite harmless to humans and tend to be scavengers.  Barklice make up an obscure group of insects and many entomology students simply identify them to “order” level as this group can be challenging to narrow down further to family, genus, or species.

Group of Cerastipsocus venosus juveniles. Note the striped abdomens which make them easy to identify. Photo submitted to UW Insect Diagnostic Lab.iny

If you haven’t encountered Cerastipsocus venosus (aka “tree cattle”) before, it might catch you off guard to find a group (formally known as a “herd”) of these small insects hanging out together on the bark of a tree or a rock in your yard.  The tiny juveniles are particularly striking with yellow stripes on their abdomens.  The adults are larger (up to 1/4″ long) and possess black wings.

A Cerastipsocus venosus adult. Note the black wings, which are only found in the adults. Photo submitted to UW Insect Diagnostic Lab.

Rest assured, these barklice pose no threat to trees or other plants in our yard and these native insects simply nibble on lichens, and pieces of dead tree bark.  Every year I get many reports of these insects in mid- and late- summer at the UW Insect Diagnostic Lab and there’s no need to spray or do anything about these if you spot them in your yard.  These barklice don’t seem to stay in the same place for very long, so perhaps their herds just move along looking for greener pastures.


*Some insects are able to reproduce asexually, and don’t technically have to find a mate…

Snow Fleas: When a “Flea” isn’t a Flea

Fleas (Order Siphonaptera) can be an unwanted surprise—no one wants fleas on their pets or in their house.  Our commonest flea on both cats and dogs in the Midwest is the “cat flea” (Ctenocephalides felis), and this same species can also live on a wide range of wild animals.  Cat fleas may be annoying but can be controlled with a diligent multi-pronged approach: chatting with your veterinarian to pick a proper treatment for your pet and regular and thorough vacuuming. In heavy infestations, carpets and furniture may also need to be treated.  While fleas could be encountered anytime of the year, I see the vast majority of flea cases at the UW Insect Diagnostic Lab in late spring and summer.  In contrast, cases of fleas are few and far between during the winter months due to the dry conditions and lower temperatures which can be hard on these insects.

There is one type of “flea”, however, that I see regularly through the winter months—the “snow flea”.  Snow fleas (Hypogastrura nivicola   and close relatives) aren’t actual fleas and rather than a pest, these harmless creatures are a beneficial curiosity.  Their cold tolerance and ability to launch themselves into the air account for their nickname.

Up-Close View of a Snow Flea. Photo Credit: Daniel Tompkins via Wikipedia

The snow fleas we’re talking about technically aren’t even insects and belong to a closely related group of arthropods known as springtails (Collembola).  Springtails get their name from the furcula—an anatomical structure on the underside of their bodies, which springs downwards to catapult them up into the air.  Springtails can’t “jump” very far by human standards given their tiny size (less than a tenth of an inch long), yet they can easily launch themselves many times their own body length in a mere blink of an eye (video).

The snow flea is unusual for springtails (and most arthropods) in the fact that these creatures can remain quite active during the winter months.  As discussed in this post from last March, insects and other arthropods have a variety of strategies to make it through winter, ranging from migration to freezing solid in some cases.  The vast majority of arthropods are inactive during winter, but some, like the snow flea, seem perfectly content wandering out on the snow.  With their tiny size and dark grayish bodies, snow fleas can almost look as if someone had dumped out a pepper shaker on the snow.

Snow fleas in their element. Photo Credit: Christa R. via flickr.

Their ability to remain active at frigid temperatures is due to the concentration of specific proteins in their bodies, which serve as a cryoprotectant or natural “antifreeze”.  During the rest of the year, these creatures simply blend in amongst fallen leaves where they scavenge upon decaying materials and help with nutrient recycling.

These creatures are truly a winter curiosity if you haven’t encountered them before.  The next time you’re out snowshoeing or cross-country skiing, keep an eye out for these tiny acrobats on the snow.


Final Note: Overseas, our friends in the UK have different creatures they refer to as snowfleas—insects from the genus Boreus, which we’d call “snow scorpionflies” in our area.

Insects on the Move: Viburnum Leaf Beetle

A perk of being an entomologist is being able to better understand the world through the tiny creatures around us.  However, this can also be a bit disheartening at times.  While vacationing in Florida several years ago, I remember visiting the beach and the first three arthropods I encountered were out of place—a honey bee (originally arrived with Europeans), a millipede from Caribbean islands, and a weevil from Sri Lanka.  I doubt any other beachcombers recognized the international gathering amongst the dunes that day.

A honey bee (Apis mellifera) on a Florida beach.
A honey bee (Apis mellifera) on a Florida beach. Honey bees arrived in North America with Europeans and aren’t native to our area. Photo credit: PJ Liesch, UW Insect Diagnostic Lab

Seeing the world this way really reinforces the notion that humans play a critical role in the movement of species around the planet.  Scientists can make their best predictions about invasive species, but there are plenty of surprises in terms of when and where a given species will turn up.  For high priority invasives, designated surveys and inspections are conducted by government agencies to help monitor the situation.  The general public can also play an important role in documenting the presence and distribution of invasive plants, insects, and other organisms.  In Wisconsin, for example, the Wisconsin First Detector Network (WIFDN) uses a network of citizen scientists and a smartphone app to document invasive species.       

White-spotted caterpillar of the purple carrot seed moth (Depressaria depressana) found in Middleton, Wi in July, 2019. Photo credit: PJ Liesch, UW Insect Diagnostic Lab

In some cases, invasive species are simply stumbled upon.  Back in July, I bumped into the first case of the purple carrot seed moth in Dane county while riding some local mountain bike trails.  Along these lines, my wife and I were walking our dogs in early November when I spotted some suspicious damage on a row of viburnum shrubs.  A closer look revealed the distinctive feeding holes and egg pits of the invasive viburnum leaf beetlethe first evidence of an established infestation in Dane County

Egg pits of the viburnum leaf beetle on a viburnum twig.
Egg pits of the viburnum leaf beetle. Females chew small depressions in twigs of viburnum shrubs, lay several eggs, and cover the eggs with pits of chewed plant materials. Photo credit: PJ Liesch, UW Insect Diagnostic Lab.

The first established case of the viburnum leaf beetle in Wisconsin occurred in 2014 in northern Milwaukee county and a more detailed account of this species can be found in the original post on this blog.  Unfortunately, this invasive beetle has made some dramatic jumps on the map over the last few years—likely due to human movement of infested plant materials.  Back in 2017, VLB was detected in Oshkosh (Winnebago Co.). In June of 2019 viburnum leaf beetle was spotted in Hurley (Iron Co.) in far northern Wisconsin and was detected across the border in Ironwood, Michigan shortly thereafter. Other detections in 2019, include Racine and Walworth counties. 

Map of the the viburnum leaf beetle in Wisconsin.
Known distribution of the invasive viburnum leaf beetle in Wisconsin as of November 2019. Counties shaded in light blue had infestations known prior to 2019. VLB was detected in dark blue counties for the first time in 2019. Map: PJ Liesch, UW Insect Diagnostic Lab.

The viburnum leaf beetle can cause significant damage to viburnum shrubs and is already wreaking havoc in the greater Milwaukee area.  Viburnums, including American cranberrybush viburnum, arrowwood viburnum, and others are widely distributed in both urban and natural settings, meaning that Wisconsinites now need to keep an eye out for this damaging insect in new parts of the state.


To learn more about the appearance, damage, and biology of the viburnum leaf beetle, visit the original post and this factsheet.

A Celebration of Insects

It’s a funny world we live in.  We hear regular reports of insect declines in the news and still get bombarded with constant ads for services pitching a mosquito free yard all summer and a grub free lawn.  But what about simply appreciating insects and the critical roles they play in our everyday lives?  

That’s a goal of the first ever Wisconsin Insect Fest being held at the Kemp Natural Resources Station  in Woodruff, Wisconsin later this month.  The two-day event—being held on Friday, July 26th and Saturday, July 27th—is a celebration of insects.

Wisconsin Insect Fest is free, open to the public, and will feature a wide range of activities for insect enthusiasts of all ages.  Topics will range from how to observe and collect insects, to the role of insects in the ecosystem, entomophagy, and even forensic entomology.  The Wisconsin Insect Fest will also feature The Great Wisconsin Bug Hunt—a 24-hour BioBlitz activity to see just how many arthropods can be spotted at the Kemp station in a 24-hour period (including a night time activity in conjunction with National Moth Week).

If you love insects, join in the festivities at the Wisconsin Insect Fest later this month or check out the event website for details: tinyurl.com/WisconsinInsectFest

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.

 

 

 

Mantid Mania

If you spotted one of the unusually large green or brownish insects working on its kung fu moves in late summer, you would have undoubtedly spotted a praying mantis.  These insects are an unusual sight in Wisconsin as we really don’t have native mantids in our area.  The closest native mantid, the Carolina mantis (Stagmomantis carolina), occurs in the southeastern US and does makes its way as far north as Iowa, Illinois, and Indiana.  A stray may show up in Wisconsin on occasion, but this seems to be an exception, rather than the norm.

A female Chinese Mantis (Tenodera sinensis) blends in on vegetation in late summer. Photo credit: Jill Schneider.

When mantids are found in the upper Midwest, the culprits are typically two introduced species: the European mantis (Mantis religiosa) and the Chinese mantis (Tenodera sinensis).  Both of these species have been in the country since the late 1800’s and have become well established in North America.  Of these, the Chinese mantis stands out with its sheer size as it can approach 5 inches in length with its outstretched legs.  The Chinese mantis is our largest and commonest species, based on observations.

Overall, mantids are much more common in southern states. The scarcity of these insects in the upper Midwest has a lot to do with their life cycle.  For the species in our region, females lay egg pouches (oothecae) in late summer or early fall in exposed locations—twigs, gardening stakes, and similar spots.  If there’s a harsh winter, these exposed egg masses face the brunt of the cold and mortality is high.  As a result, the vast majority of Wisconsin’s mantid sightings are restricted to southern and eastern counties where temperatures are slightly warmer during the winter months.  In 2017, there was a distinct increase in mantid sightings, likely due to the two consecutive mild winters in our area.  Assuming an egg case makes it through the winter, hundreds of juvenile mantids emerge in spring and surviving individuals reach maturity by late summer.

Chinese mantis (Tenodera sinensis) cleaning a leg. Note the enlarged (“Popeye-like”) raptorial forelegs lined with spines to subdue prey. Photo Credit: Jill Schneider.

Not only are mantids fascinating creatures to watch, but they’re impressive predators as well.  A number of adaptations place mantids amongst the top predators of the insect world.  First off, large eyes give them excellent stereoptic vision—if you’ve ever watched a mantis, they’ve watched you as well.  Camouflage also benefits many mantids, with color patterns that allow them to stealthily hide on plants, waiting to ambush unsuspecting prey with ninja-like agility.  The tropical orchid mantis (Hymenopus coronatus), even takes camouflage to an extreme with bright pink coloration to blend in on flowers.   The grisliest adaptation would be the enlarged “raptorial” forelegs armed with spines, which allow mantids to rapidly seize and impale prey and hold them in a final, lethal embrace as they begin to eat.  Mantids typically eat a variety of flies, moths, bees, butterflies, and other insects, but large mantids have even been known to prey upon birds on occasion [Note: it’s pretty gruesome and involves eating brains!].  Mantids aren’t picky eaters, so cannibalism can even be a significant challenge to those trying to raise them.

While uncommon in our area, reports of mantids may continue to increase in the future with climbing temperatures and milder winters—something to keep an eye out for!

 

Wisconsin’s Top Insect Trends of 2016 (#5 – #1)

In this post, we’re continuing to count-down 2016’s top insect trends in the state.  This is the final post in a three part series.  Part I (2016’s diagnostic lab statistics) can be found here and Part II (Top Insect Trends Numbers 10-6) can be found here.

#5: The spread of the emerald ash borer increased dramatically in the state last year. Photo Credit: Howard Russell, Bugwood.org.
#4: Fall invading insects, such as boxelder bugs are well known, but the strawberry root weevil and other weevils can sneak indoors during the summer months. Photo Credit: Whitney Cranshaw, Bugwood.org.
#3: Several scarab beetles, including the rose chafer caused notable plant damage last year. Photo Credit: Clemson University Extension, Bugwood.org.
#2: An elusive adult rabbit bot fly. Photo Credit: Quentin Sprengelmeyer.
#2: An inch long bot fly larva from a mouse. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab.
#1: Fierce mosquito pressure in many parts of the state combined with the Zika stories in the news gave mosquitoes the top spot in 2016's insect trends. Photo credit: Susan Ellis, Bugwood.org.

 

5) Metallic Wood Boring Beetles
Two different metallic wood boring beetles (Family Buprestidae) had strong years in 2016. The first, the emerald ash borer, is no stranger to Wisconsinites these past few years. While there were only 3 new counties (Portage, Wood, Sawyer) added to the state quarantine map in 2016, there were over 80 municipalities with their first confirmed EAB infestation last year (out of 227 municipalities with documented EAB finds at the end of 2016). With that said, EAB has greatly picked up steam these past few years and is attacking ash trees at a rapid rate in Midwest.

Another metallic wood borer that seemed to have a good year was the twolined chestnut borer. Unlike the invasive emerald ash borer, the twolined chestnut borer is is native to North America and tends to attack stressed trees (oaks). In these cases, trees might be stressed by factors such as disease, drought stress, winter injury, or damage from other insects. The UW Insect Diagnostic Lab noticed a distinct increase in cases of the twolined chestnut borer this past summer, although the underlying stress might have begun affecting trees several years ago. With the high value of oak trees in the landscape, this insect is definitely a pest that tree care companies should have on their radar for the near future.

4) Home-Invading Weevils
Many Wisconsinites experience or at least are familiar with insects that sneak indoors in the fall, such as boxelder bugs and multicolored Asian lady beetles. There’s also a group of broad-nosed weevils that happen to sneak indoors during the summer months. Species in this group include the strawberry root weevil, the imported longhorned weevil, and others. Once indoors, these weevils tend to stumble around in a slow, somewhat tick-like manner, causing concern to homeowners. But fear no weevil, for these insects are completely harmless. A broom or vacuum cleaner are often the best tools to deal with them. While broad nosed weevils can be somewhat common, reports coming in to the UW Insect Diagnostic Lab suggest that numbers of these home-invading beetles were up in 2016.

3) Scarab Beetles
A number of scarab beetles had noteworthy activity in 2016, including several important landscape pests. Scarab beetles can be an extremely common group of insects, with well over 100 species in Wisconsin alone. Perhaps the best known (and most infamous) member of this group would be the Japanese beetle (Popillia japonica), which seemed to rebound last year after a few quiet years. In parts of the state with sandy soil, the rose chafer was present in high and damaging numbers. Similar to Japanese beetles, rose chafers are fond of feeding on a wide range of plants from landscape shrubs to fruit trees.

Two other scarab beetles were noteworthy in 2016: the Northern masked chafer and the European chafer. This past year marked the first year that the larvae of these beetles (white grubs) had been found damaging turfgrass in the state: Rock County (NMC) and Door county (EC). Previously, turfgrass managers only had to contend with the white grubs of Japanese beetle and the occasional May/June beetle.

2) Bot Flies
[Disclaimer: bot flies are not for the faint of heart! If you’re preparing to eat lunch, you may want to skip down to #1.]
Bot Flies-Click to Read

If you’re not familiar with bot flies, these creatures may seem like something out of a science fiction movie. In their simplest terms, bot fly larvae are essentially large, flesh-inhabiting maggots. When fully mature, the maggots can be over an inch long and are covered with tiny backward-facing spines, making removal nearly impossible from their host. Adult bot flies are very short lived and somewhat resemble bumble bees or certain horse flies in their size and coloration. In a typical year, the UW Insect Diagnostic Lab might receive 1-2 reports. For whatever reason, bot flies had a great year in 2016 and several dozen reports came in to the lab. The common species observed in Wisconsin last year were from the genus Cuterebra and parasitize small mammals such as: mice, chipmunks, squirrels, and rabbits.  The maggots live and feed beneath the skin of their mammal host for weeks before popping out to pupate.  The mammal hosts generally seem to tolerate their companions, although the concept of bot flies may give you a creepy-crawly feeling.
[Bonus material: there is a bot fly (Dermatobia hominis) in South and Central America that affects humans]

 

1) Mosquitoes
With all the stories about the Zika virus in the news, it was difficult to avoid hearing about mosquitoes in 2016. In addition, with the heavy rains many parts of Wisconsin received last year, it was equally challenging to venture outdoors and avoid mosquitoes. In many parts of the state, mosquito pressure was severe last year, giving mosquitoes the top spot on the 2016 list. If there’s a silver lining to the mosquito story last year, it has three parts:

  • The mosquitoes that were dreadfully abundant last year (floodwater mosquitoes) aren’t important vectors of human disease. Yes, they might have ruined that evening cookout, but at least they weren’t making anyone ill.
  • Reports of mosquito-borne diseases (such as West Nile Virus) were relatively low in the state last year.
  • Zika virus was not a major issue in Wisconsin, as the mosquito species responsible for that disease haven’t been found here [Read more about this topic in this post]

Wisconsin’s Top Insect Trends of 2016 (#10 – #6)

This post examines 2016’s top insects trends through the eyes of the UW Insect Diagnostic Lab and is the second post in a three part series.  The first post of the series (2016’s diagnostic lab statistics) can be found here.

#10: Boxelder bugs had a surprisingly good year, despite the rainy conditions. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab.
#9: Scale insects, like these lecanium scales, have been very abundant the last two years in Wisconsin. Photo Credit: Ronald S. Kelley, Bugwood.org
#8: Reports of juvenile brown marmorated stink bug indicate that this invasive species is reproducing the in the state. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab.
#7: Fungus gnats were very abundant in late summer and fall with rainy conditions seen in many parts of the state. Photo Credit: Whitney Cranshaw, Bugwood.org
#6: Silk moths, such as this luna moth, were frequently spotted in 2016. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab.

 

10) Boxelder Bugs:
Many insects (like mosquitoes and fungus gnats) thrived in Wisconsin’s rainy conditions last year. However, heavy rains can also be a blessing in disguise when it comes to certain insect pests. Gypsy moth caterpillars, for example, can be killed off by the entomopathogenic fungus Entomophaga maimaiga under damp conditions. Heavy spring rains the past few years likely encouraged this fungus, which has helped keep gypsy moth numbers low in many parts of the state. Rainy conditions can also encourage a fungal disease of boxelder bugs. With the rainy conditions in many parts of the state, boxelder bug populations were expected to be low last year. Disease pressure from the fungus must have been limited in 2016 as boxelder bug numbers were surprisingly high in many parts of the state, much to the chagrin of homeowners hoping to avoid the tiny red-and-black home visitors in the fall.

9) Scale Insects
Scale insects are truly bizarre creatures. For example, the magnolia scale (#1 of 2015’s top insect stories) can look more like a fungus than an actual insect. As in 2015, many reports of scale insects came into the UW Insect Diagnostic Lab last year, especially during the spring and summer months. The most commonly encountered type was the lecanium scale, which can blend in on twigs and resemble deformed plant buds. Both magnolia and lecanium scales produce copious amounts of sticky, messy, honeydew, which can attract ants and wasps, and lead to the growth of black sooty mold. In many cases, scale insects can be notoriously difficult to control. Luckily, over time there are a number of natural enemies (tiny parasitic wasps) that help bring outbreaks under control. With two consecutive years of high scale insect populations, 2017 may be the year that the natural enemies help bring the situation under control.

8) Brown Marmorated Stink Bug
Reports of the brown marmorated stink bug in 2016 were very similar to the previous year. Dozens of sightings of this relatively new invasive species were reported, mostly from the southern part of Wisconsin. Dane County (Madison area) continues to be the hot spot of BMSB activity in the state with additional activity in the Milwaukee/Waukesha area and the Fox River Valley. A few counties had their first confirmed reports of BMSB in 2016: Sauk and Columbia. Also of interest were the first reports of these insects on plants (previous reports involved insects overwintering in buildings). In addition, some of the first observations of juveniles and mating adults occurred in the state. Those observations confirm that the brown marmorated stink bug is breeding in Wisconsin and is likely to continue to increase its numbers in the future. This insect is expected to be a concern for vegetable growers, fruit growers, and home gardeners in the coming years.  For more information on this emerging insect pest, there’s a series of articles available at  Wiscontext.org.

7) Giant Silk Moths
Some of the Midwest’s largest insects had a big year in 2016—the giant silk moths. Wisconsin is home to a number of giant silk moth species, including the cecropia moth, polyphemus moth, imperial moth, promethea moth, and the ever-so-elegant luna moth. Historically, these sizable moths [4-5”+ wingspan] used to be more common in many parts of the country, although their numbers seem to have declined over time. This may be partly due to landscape/habitat changes, urbanization, and accompanying light pollution. Parasites are likely a key factor in this situation.  The parasitic fly Compsilura concinnata, originally imported to control pest caterpillars such as the invasive gypsy moth, also happens to attack and kill a number of wild silk moth caterpillars  and can have significant impacts on their populations. However, numerous reports coming in to the UW Insect Diagnostic Lab indicated that giant silk moth numbers might have been up in 2016 compared to the past few years.

If you ever come across one of these majestic and fascinating creatures, consider yourself lucky—adults are notoriously short-lived as they can be a substantial meal for bats. Species such as the luna moth even have special structures to help evade sonar detection by bats.

6) Fungus Gnats
If you noticed plagues of tiny, dark-colored flies in your backyard in late summer and fall, you certainly weren’t alone. Spurred by the rainy conditions, fungus gnats were extremely abundant in many parts of the state last year. As larvae, fungus gnats live in damp, decaying organic materials—rich soil, decaying plants, compost piles, and similar. Fungus gnats themselves are harmless and don’t bite, but could have been a minor nuisance in the backyard. In many cases, fungus gnats were also spotted indoors this fall. In those situations, the fungus gnat larvae could have easily been living in the damp soil of potted plants brought indoors for the winter months. If over watering of indoor plants continued, the fungus gnats persisted indoors as well.

Up Next:  Wisconsin’s Top Insect Trends of 2016 (Numbers 5-1) 

State of the Lab Address 2016

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 2016

Caseload
It was another busy year around the UW Insect Diagnostic Lab. By the end of 2016, the lab had identified 2,444 specimens, slightly up from 2015’s record number of 2,423 specimens. As in 2015, ~95% of these cases came from within Wisconsin, with just over 4% of samples coming from other states and ~1% coming from other countries.

1-Wisconsin Cases-2016
2-USA Submissions-2016
3-World Map-2016

 

Sample Submission
Overall, lab statistics were very similar to other years in the recent past, with roughly half of the lab samples coming in during the months of June, July, and August. The majority of samples consisted of digital images coming in from the general public. County Extension offices and agents accounted for the next largest number of samples, having submitted over a quarter of all samples processed in the lab. Other sources of samples included the green industry, medical and public health professionals, pest control professionals, farmers and agricultural consultants, and other colleagues in the UW system and state or federal agencies.

4-Monthly Chart-2016
5-Types of Samples-2016
6-Who Submits Samples-2016
7-Sample Source-2016

 

Sample Identity
Very similar to 2015, over 90% of the specimens came from five major groups of insects:

  • 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

Click for larger view

Outreach efforts of the IDL in 2016 included over 90 public talks at a variety of events throughout the state, over 30 media interviews, and regular appearances on Wisconsin Public Radio’s “The Larry Meiller Show”.  Numerous articles and other publications came out of the lab in 2016, including a Wisconsin Bee Identification Guide and an urban pollinator conservation guide to help increase awareness of pollinators and pollinator conservation. The services provided to Wisconsin residents by the UW Insect Diagnostic Lab and its outreach efforts are one of the many examples of the Wisconsin Idea.

Up Next: Wisconsin’s Top Insect Trends of 2016 (Numbers 10-6)