Tag Archives: 2016 Lab Highlights

Beetles, Flies, IDL Highlights, In the News, Invasive Species, Outdoor Insect Invaders

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]
IDL Highlights

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)