Will we see Brood X cicadas in Wisconsin or the upper Midwest this year? Read on to find out: Cicadas—they’re all over the news and soon to be out by the billions. All this buzz is about periodical cicadas, a group of species from the genus Magicicada which emerge once every 17 years (or every 13 years in some cases). Periodical cicadas are only found in the eastern United States and vary by location and the timing of their activity. To help categorize these insects, entomologists refer to each cohort of cicadas as a “brood” and have numbered them with Roman numerals. This year’s cicadas are referred to as Brood X (i.e., Brood ten) and last emerged in 2004.
Periodical cicadas are amongst the longest lived insects and their long life span and massive emergences are believed to be a survival strategy—by overwhelming predators with sheer numbers, they simply can’t all be eaten. But the wait for their appearance is a long one. Periodical cicadas spend 17 years below ground as juveniles (nymphs) feeding on the sap from tree roots, before making their way above ground. Their emergence is associated with soil temperatures, and when the soil has warmed to 64˚F, they emerge. This corresponds to parts of April, May, or June depending on the location on the map. Once they make their way above ground, the cicadas molt and transform into adults. Shortly thereafter, a raucous mating free-for-all commences. After mating, the females cut small slits into twigs of trees to deposit their eggs. The eggs hatch and the juveniles head to the soil for their lengthy development. Periodical cicadas don’t live long as adults (a matter of weeks), so it’s a long build up to a noisy grand finale.
With all the attention in the news, many Wisconsinites and other Midwesterners are wondering if they’ll be able to see or hear Brood X cicadas in their area this year. For Wisconsin, Minnesota, Iowa, and most of Michigan and Illinois the answer is no—although they aren’t terribly far away either. Brood X cicadas can be found in over a dozen eastern states, but primarily emerge in three main pockets:
Indiana, Ohio and nearby slivers of eastern Illinois and southern Michigan
Southern Pennsylvania and parts of nearby Delaware, Maryland, Virginia, New Jersey, and New York
Eastern Tennessee and nearby parts of North Carolina and Georgia
While we won’t see Brood X cicadas here in Wisconsin, we will see other periodical cicadas in the not so distant future. Wisconsin is home to Brood XIII cicadas, which last emerged in 2007, meaning that the next big emergence in the Badger State is only a few years off in 2024. In the meantime, we’ll still see and hear plenty of our typical “dog day” cicadas during the warm days of summer. To learn more about Brood XIII cicadas in Wisconsin, check out this post from last year.
When it comes to insects that bite humans, there’s simply not a very long list of “common suspects”—especially during the cooler months. Things such as bed bugs, fleas, and lice are all fairly straightforward to confirm. However, I do occasionally bump into other creatures that can bite, such as bird mites, pirate bugs, and others. I also bump into cases where clients are experiencing biting or crawling sensations, but no insects of concern are found. One of my tasks at the UW Insect Diagnostic Lab is to evaluate a situation to see if any of the less-common possibilities might be at play. If not, then I start to suspect delusory parasitosis (aka Ekbom’s Syndrome), which entomologists encounter on a fairly regular basis. In one recent case, I was scratching my head for a while until I was able to confirm the presence of hackberry psyllids (Pachypsylla spp.)—tiny, jumping, biting insects that pop up under the right conditions.
Hackberry psyllids (pronounced “sill-ids”) resemble miniature cicadas and are about 1/10th inch long. They have mottled grayish bodies and are sometimes called “jumping plant lice” or “hackberry nipple gall makers”. True to their name, these insects are associated with hackberry trees (Celtis occidentalis), which are commonly planted in the landscape as both yard and street trees.
In spring, overwintered psyllids lay eggs on emerging hackberry leaves. After the young psyllids emerge, their feeding causes unusual distortion of the leaf tissue, resulting in small “nipple-like” lumps (galls) on the leaves. Such galls are actually very common and most hackberry trees possess the characteristic galls to some extent. They may be alarming in appearance, but the galls are harmless to the trees and are essentially a minor “cosmetic” issue. The young psyllids feed and develop within the protection of their leaf galls. Eventually, they complete their development and the next generation of adult psyllids emerges from the galls.
At this point, you might be wondering how these tiny plant-feeding insects end up bugging humans. Similar to boxelder bugs and Asian lady beetles, hackberry psyllids seek out sheltered overwintering spots in the fall and can easily invade homes and other structures. With their tiny size, hackberry psyllids can be a bit harder to keep outdoors. They are often overlooked and can easily squeeze through most window screens. Indoors, these insects face death by desiccation due to the dry conditions, but can be a nuisance as they jump or fly around. Occasionally, they’ll invade in fall and their activity resumes during warm spells over the course of a winter.
In addition to being a nuisance, hackberry psyllids can “bite”. These insects feed on plants (hackberry trees), but they do have a habit of “testing” various surfaces they land on to assess if another food source has been found. If they happen to land on exposed skin, they’ll use their slender, beak-like mouthparts to probe, which can feel like a small pinch. When they do this, hackberry psyllids don’t feed on blood or inject any kind of venom, but it certainly can be unpleasant.
The good news is that unless you have a hackberry tree in your yard or very close by, you probably won’t bump into appreciable numbers of these tiny insects. If you do encounter them at your home, leaving windows closed on warm fall days (especially on south and west-facing sides of your house) or replacing window screens with a finer sized mesh can go a long way towards keeping them outside.
In the grand scheme of things, most insects (and spiders) are loners. Perhaps they set a good example for us in 2020 with their social distancing.
Of course, insects have to find a mate to reproduce at some point in their lives*, but out of the 1 million+ described insect species, being truly “social” isn’t the norm. There certainly are some well-known examples of insects that are eusocial—i.e., they live together as a colony. Examples include ants, certain types of wasps (such as yellowjackets and paper wasps), some bees, termites, and a few other interesting examples. However, there are many insects that are much more solitary in their habits. If you think of our bees in the Great Lakes region, we have roughly 500 species. Other than honey bees, bumble bees and a few others, the vast majority of these species are solitary creatures with each female doing her own thing.
Interestingly, there’s a quirky insect that can be commonly encountered this time of the year and it missed the memo on social distancing. I’m referring to an interesting species of barklouse (Order Psocodea): Cerastipsocus venosus. Barklice are relatives of true lice (e.g., head lice and pubic lice) but they’re really quite harmless to humans and tend to be scavengers. Barklice make up an obscure group of insects and many entomology students simply identify them to “order” level as this group can be challenging to narrow down further to family, genus, or species.
If you haven’t encountered Cerastipsocus venosus (aka “tree cattle”) before, it might catch you off guard to find a group (formally known as a “herd”) of these small insects hanging out together on the bark of a tree or a rock in your yard. The tiny juveniles are particularly striking with yellow stripes on their abdomens. The adults are larger (up to 1/4″ long) and possess black wings.
Rest assured, these barklice pose no threat to trees or other plants in our yard and these native insects simply nibble on lichens, and pieces of dead tree bark. Every year I get many reports of these insects in mid- and late- summer at the UW Insect Diagnostic Lab and there’s no need to spray or do anything about these if you spot them in your yard. These barklice don’t seem to stay in the same place for very long, so perhaps their herds just move along looking for greener pastures.
*Some insects are able to reproduce asexually, and don’t technically have to find a mate…
Elongate hemlock scale attacks over 40 species of conifers—especially hemlocks which can be common throughout the Appalachian Mountains, and Fraser firs and balsam firs, which are commonly grown as Christmas trees. Certain types of spruces and pines can also be attacked. Established populations of elongate hemlock scale are not known from Wisconsin, but a recent detection of this pest in the state raises concerns for Christmas tree growers, the plant nursery industry, tree care professionals, and homeowners with conifer trees in their yards. Forested areas are also at risk, meaning the stakes are potentially high with this insect.
While insect activity is quiet in the Midwest this time of the year, we’re hearing about the elongate hemlock scale now due to its Christmas connection. Similar to 2018, the Wisconsin Department of Agriculture, Trade and Consumer Protection recently found that fir Christmas trees, wreaths, and other holiday decorations infested with EHS had been shipped to Wisconsin from North Carolina. The picturesque Blue Ridge Mountains of western North Carolina provide ideal habitat for Fraser firs—one of the most popular species of Christmas trees. North Carolina grows approximately a quarter of all the Christmas trees sold in the US each year and with elongate hemlock scale established in that state, it increases the risk of movement of this invasive insect around the country.
Elongate hemlock scales look unusual as far as insects go. These insects have traded mobility for defense—they hunker down on plants and produce a waxy coating which helps protect them from predators and parasites. As a result, elongate hemlock scales aren’t easily recognizable as insects since the usual signs of segmentation—body regions, legs, antennae—are not readily visible. Instead, these insects have a vague, oblong appearance. Adult females are small (just under 1/10th of an inch long) and are covered with a waxy brownish coating. They are typically found on the undersides of needles. Males are slightly smaller and develop beneath pale whitish coverings. Mature males do emerge with wings but are weak fliers and travel short distances to mate with the wingless, immobile females.
Under their protective coatings, these insects use needle-like mouthparts to suck fluids from plants. With their small size, damage occurs when large numbers of individuals infest plants. Their waxy coverings also limit the effectiveness of insecticides, making EHS a challenging pest to control if they become established.
Because elongate hemlock scale has been detected in Wisconsin this year in Christmas trees and other holiday decorations, a key objective at this point is to prevent this insect from getting a foothold in the state. By all means, continue to enjoy your holiday decorations, but when you’re ready to remove these materials, take the following steps to help prevent this insect from becoming established in Wisconsin:
1) If your Christmas tree or natural wreaths, garlands, or other decorations are from a local Christmas tree farm or elsewhere in Wisconsin, no special precautions are needed for elongate hemlock scale. Because EHS is not established in the state, these materials can be removed as usual at the end of the holiday season.
2) If your Christmas tree or natural wreaths, garlands, or other decorations are from a big box store, grocery store, or similar vendor, or if you are not sure of the origins of these materials, it is advised to check these materials for signs of elongate hemlock scale (i.e., brown spots on the undersides of needles). The Wisconsin Department of Agriculture, Trade, and Consumer Protection is advising that infested or suspect materials preferably be burned (check with the DNR for any burning restrictions in your area). Alternatively, such materials could be bagged and discarded as waste. Infested or suspect materials should not be composted or used for wildlife habitat in your yard.
For additional information on elongate hemlock scale, visit the WI-DATCP EHS page and the recent press release about the 2019 EHS detection.
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.
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.
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.
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.
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.
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:
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.
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.
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.
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.
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.
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.
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!
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.
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.