Tag Archives: 2014 Lab Highlights

Wisconsin’s Top 10 Insect Stories of 2014 (Part III)

Below you’ll find the third and final part of a series describing the Top 10 insect-related stories of 2014 from Wisconsin.


4) Hexagenia Mayflies and Fishing Spiders: If you love insects and/or fly fishing, you might have been thrilled to hear about the massive mayfly hatch along the Mississippi River in late July. These emergences happen yearly, but the mass emergence in the evening of July 20th was one of the largest in decades. We’re not talking about thousands or millions of insects, but billions of insects emerging at the same time. So many mayflies emerged simultaneously that the insects showed up on National Weather Service weather radar (read the full details here).  When these emergences occur, the insects can accumulate on bridges and streets making roadways slippery.

Hexagenia 20 July 2014
Mayfly emergence on the evening of July 20th. Source: National Weather Service.

The insect involved is the Hexagenia mayfly. The young (nymphs) live in the sediment at the bottom of the Mississippi River and feed on bits of organic matter in the water. The presence of the adults above water is truly an ephemeral phenomenon; it’s even reflected in the name of their group: the Order Ephemeroptera. Adult Hexagenia mayflies only live for a matter of hours, which leads them through a frenzied courtship period. Shortly thereafter, they’re done for.

Around the same time as the mayfly emergence, the fishing spider stories made their way around television, radio, and Facebook and the phone calls and emails came flooding in. Despite the hype, fishing spiders are native to Wisconsin and can actually be fairly common. Fishing spiders aren’t truly aquatic, but they do tend to hang out near water. They’re among our largest spiders in the state, and can be large enough to capture and feed on small minnows.

3) Spotted Wing Drosophila: One of our newest invasive species had another strong year in 2014. The spotted wing drosophila (SWD) is originally from parts of Asia, and was discovered in the US in 2008. Within two years, it had popped up in Wisconsin. Like other fruit flies, SWD loves fruit.  The main difference is that our run-of-the-mill fruit flies lay eggs in overripe or spoiled fruit.  In contrast, SWD females have a hacksaw-like egg-laying structure, which can be used to slice into ripe or ripening fruit to lay eggs. As a result, SWD has become a major issue for fruit growers in the state.  Late-season berry crops (raspberries, blackberries, strawberries) are hit the hardest. SWD has been found statewide, and will continue to be a major concern for late-season fruit growers for the foreseeable future.

2) Pollinators: You don’t have to listen to the news very long before you hear a reference to pollinators. Unfortunately, much of the news on the topic paints a bleak picture: pollinators of all kinds are in decline at the moment. Honey bees, bumble bees, other native bees, and butterflies like the Monarch are all facing declines. Unfortunately, it’s not a black-and-white situation, and there’s no simple solution to the issue at hand. Instead, many different factors, such as habitat loss, diseases, parasites, land-use practices, pesticides and other factors may all be involved one way or another.

We may not think of the connection to pollinators when we visit the grocery store, but without the pollination services of insects, the produce section would be scarce. It turns out that roughly a third of the world’s agricultural crops rely on pollinators. Without pollinators, you’d have a hard time finding apples, strawberries, melons, tomatoes, and many of our common food items.

Flowering plants in your yard provide resources to bees. Photo Credit: PJ Liesch
Flowering plants in your yard provide resources to bees. Photo Credit: PJ Liesch

If there’s a silver lining to the situation, it’s that attention has been brought to the topic. In June of 2014, the White House announced the creation of a pollinator health task force to develop a national strategy to help prevent pollinator losses and help improve pollinator habitat.  While it may seem like a small step, individuals can help pollinators by making their own yards pollinator friendly. Incorporating native plants into the landscape, providing nesting habitat for solitary bees, and using caution with pesticides are all ways to help pollinators in our own yards.  Tips for accomplishing this can be found here.

1) Emerald Ash Borer: The emerald ash borer (EAB) continues to be one of the biggest insect stories in the state. This invasive pest is originally from Asia, but has been wreaking havoc on Wisconsin’s ash trees since 2008. Spread within the state seemed to progress slowly at first, but 2014 saw dramatic changes in our quarantine map in the state. In early 2014, we had a total of 21 Counties quarantined for EAB. By the end of the year, 16 additional counties had been added to the map to bring the total up to 37 counties. While most of the quarantined counties are in the southern half of the state, Douglas and Oneida counties in the north are also quarantined. Unfortunately, this destructive pest is difficult to detect and easily transported in firewood, which means that this pest will only spread and the situation will worsen over time. While we have options to protect individual ash trees (available here), we don’t have a way to protect ash trees in woodlots or forested areas. Since its introduction into the US, the emerald ash borer has killed tens of millions of ash trees. With over 700 million ash trees in the state, Wisconsin has a lot at stake.

Wisconsin’s Top 10 Insect Stories of 2014 (Part II)

Below you’ll find the second part of a three part series describing the Top 10 insect-related stories of 2014 from Wisconsin. Part three will be released next week.


7) Missing Pests: As every landscaper and farmer knows, there’s a certain batch of insect pests that tend to pop up consistently each year. One of the biggest stories of 2014 was the scarcity of some of these “regulars” like the gypsy moth and the Japanese beetle. The reason behind this? We likely have Mother Nature to thank. Gypsy moth populations fare poorly during periods of wet weather due to the proliferation of a fungal disease that kills the caterpillars. We certainly had abundant and consistent rainfall in 2014, and several images of diseased insects made their way into the lab. In addition, gypsy moth numbers have been in a general decline for several years in the state, which is good news for oak trees.

If there’s one good thing that came out of the brutally cold winter of 2013-14, there’s the fact that it may have helped knock down the Japanese beetle populations. Japanese beetles overwinter as white grubs in the soil and tend to move just deep enough to avoid the frost line. With the pipe-bursting cold and deep frosts of last winter, it seems that the deep freeze knocked their numbers down. As a result, reports of damage from Japanese beetles were scarce this past summer. While it’s too early to tell, it’s possible that it may only be a one-year reprieve. Turfgrass researchers have reported decent grub numbers in turfgrass areas this fall, which could mean that Japanese beetle numbers could creep back up in the future.

A female Japanese beetle digging into the turf to lay her eggs. Photo Credit: PJ Liesch.
A female Japanese beetle digging into the turf to lay her eggs.
Photo Credit: PJ Liesch.

Agricultural pests were also down in 2014, with no major pest outbreaks. Two of our best known corn pests, the European corn borer and corn rootworms, had very slow years. Even migratory crop pests, such as the potato leafhopper and black cutworm, which overwinter in the gulf coasts states and migrate northward in the spring failed to take off in 2014.  (A full summary of agricultural pests can be found here.)

6) Interesting “Structural Pest” Trends: Two of our insects that commonly invade homes in the fall (boxelder bugs and multi-colored Asian lady beetles) had drastically different trends this year. Box elder bugs thrive under dry conditions, like we had in the latter parts of 2012 and 2013. Similar to the gypsy moth mentioned above, the damp conditions in 2014 likely helped keep the box elder bug number in check and prevented the widespread numbers that we’ve seen the past few years.   While the numbers of box elder bugs were low this fall, the multicolored Asian lady beetle, which had been low for the past few years, started popping up in decent numbers in certain parts of the state. One warm October day, I wandered out to the front of the entomology department building on campus to view thousands of the lady beetles flying around looking for overwintering spots.

5) Invasion of the Copper Underwing: Most folks have never heard of a moth called the copper underwing. Rightly so, as it tends to be a fairly obscure species. The caterpillars are commonly called the green humped fruitworms and can feed on fruit trees and other trees. When adults rest on trees, their grayish appearance isn’t much to write home about. However, when they display their hind wings, you’d notice the brilliant copper color and understand the common name of the insect.

Copper Underwing
Copper Underwing (Amphipyra pyramidoides); Photo credit PJ Liesch

For whatever reason, 2014 seemed to be perfect for this species. Perhaps I should have suspected that the few adults I spotted at my porch lights in late spring were the beginning of a trend. As the summer went on, I started getting reports of large numbers of these moths congregating on the sides of homes, sneaking under siding, and even leaving excrement stains on siding. All in all, I had reports of “home invasions” from over a dozen counties, mostly in the southwestern part of the state. Because this species tends to be present in low numbers, I suspect that we won’t see them amassing by the thousands again anytime soon.

Part 3: Coming soon

Wisconsin’s Top 10 Insect Stories of 2014 (Part I)

The year-end stats are in: a grand total of 2,092 insects, mites, spiders and other curiosities were submitted to the Insect Diagnostic Lab in 2014. With the ubiquity of smart phones and internet access, nearly 60% of the cases handled in the lab this year consisted either solely of digital images or as digital images accompanying a physical specimen. While the vast majority of cases came from within Wisconsin, there were occasional images and questions sent in from other states and even other countries (including Mexico, England, Ireland, South Africa, India, Guatemala, the Philippines, Spain, Portugal, Afghanistan, and Jamaica).

When it comes to the insects in Wisconsin this past year, several stories pop out. First of all, several of our “usual” pests were noticeably down this year: gypsy moth, Japanese beetle, and box elder bugs, to name a few. In contrast, the emerald ash borer had quite a year and was detected in many new locations, leading to over a dozen counties being added to the quarantined zone in the state. Then there were some cases that seemed to appear overnight: the spring mosquitoes and the massive mayfly hatch in late July.

Below you’ll find the first part of a three part series describing the Top 10 insect-related stories of 2014 from Wisconsin. Parts two and three will be released over the next two weeks.


10) Mosquitoes: Our unofficial “state bird” made news headlines across the state starting Memorial Day weekend. In some spots, the mosquitoes were so bad, that outfitters of recreational canoeing trips were turning customers away, lest they fall victim to the winged vampires.

What caused the mosquito problems in 2014? It boils down to some ideal conditions, as far as the mosquitoes are concerned. With over 50 species of mosquitoes in the state, each species has its own unique habits. Some rely on the moisture from melting snow to develop. Others wait for rain to flood depressions in the woods, where female mosquitoes had laid their eggs. Some other species rely on more permanent bodies of water, such as drainage ditches and rain-filled containers. With the late snowmelt and the heavy rains this spring and summer, our mosquitoes had plenty of moisture to use.

If there’s a silver lining of the 2014 mosquito season, it’s that the number of West Nile cases were down in the state. It turns out that our heavy rains created temporary pools out in the woods, which are favored by our “floodwater” mosquitoes. For the most part, these species are a nuisance, but don’t carry diseases like West Nile. The mosquitoes that spread West Nile tend to prefer more permanent bodies of water.  When you have lots of rain, it can sometimes cause these more permanent bodies of water to overflow, flushing the mosquitoes away. It may be counterintuitive, but our worst West Nile year of the past decade was actually the droughty year of 2012.

9) Invasive Leaf Beetles: Two different species of invasive leaf beetles (Family Chrysomelidae) were detected in Wisconsin this past year: the lily leaf beetle and the viburnum leaf beetle. Both of these beetles have unusually similar histories: they’re both known from Europe but were found in Canada in the mid-1940’s. Both made their way into New England in the 1990’s and have been popping up in other locations since then.

The lily leaf beetle was detected for the first time in Wisconsin in July in the Wausau area. This species feeds on true lilies in the landscape and has been found at a handful of sites in Marathon and Wood counties. The viburnum leaf beetle had technically been found once before in the state a few years ago in Dane county. At the time it had been found on a recently planted viburnum bush, which was removed and the insects were eradicated. Technically, the case that popped up in the Milwaukee area in late summer on an established viburnum bush is our second record in the state. Unfortunately, the original source of the insects and extent of the current infestation are not fully understood at this point.

Lily Leaf Beetle (Lilioceris lilii)
Lily Leaf Beetle (Lilioceris lilii); Photo Credit PJ Liesch

While these two beetles have only been found in a few isolated spots in the state, they have the potential to cause significant damage to their host plants, so gardeners should keep a watchful eye out for them in 2015!

8) Brown Marmorated Stink Bug (BMSB): This invasive pest was first discovered in the state in 2010. When I describe BMSB during presentations, I joke that it’s as if a mad scientist in a bad Sci-Fi movie had somehow crossed a Japanese beetle with a box elder bug.  Like Japanese beetles, BMSB will feed on hundreds of different types of plants: field crops, vegetables, fruits, and ornamental plants can all be damaged. In addition, BMSB has the habit of sneaking indoors in the fall like box elder bugs. In other parts of the US (such as Pennsylvania and Virginia), BMSM has been wreaking havoc on agricultural producers and homeowners alike. Luckily, this stink bug has been quiet the past few years in Wisconsin and we saw more of the same for 2014. While I only had half a dozen samples documented in the state this year, this is certainly a pest that everyone should be keeping an eye out for in the future.

Brown Marmorated Stink Bug (Halyomorpha halys); Photo Credit PJ Liesch
Brown Marmorated Stink Bug (Halyomorpha halys); Photo Credit PJ Liesch

Part 2: Coming soon

The Oddest Beetle on Campus

Meet Thylodrias. Kind of sounds like a character from the Game of Thrones. But alas, it’s just an odd beetle about the size of the letter “d” in size ten print.

The Odd Beetle (Thylodrias contractus); Photo credit PJ Liesch
Adult male odd beetle (Thylodrias contractus); Photo credit PJ Liesch

Although, technically speaking, this one’s not just an odd beetle. It’s more like the king of odd beetles, so much so, that it’s actually known as the odd beetle. Kind of weird for a species belonging to a very common family: dermestidae. Other relatives in the dermestid bloodline include the common hide, larder, and carpet beetles, which occasionally find their way into that old, half-empty box of spaghetti noodles at the back of the kitchen cupboard. However, if you made a closer examination of the dermestid family tree, you’d find that the odd beetle sits alone: a solitary species in its own genus.

By now, you may be wondering: what really makes this one so odd? For starters, it’s a bit infatuated with humans and we only know of the species from human habitations. We even know of specimens from archaeological sites in Iran, but these days it’s most commonly found in museums. It’s somewhat ironic that such an interesting and unusual insect has a history of lurking around the home of the UW-Madison entomology department: Russell Labs1. Like many other museum pests, the odd beetle wanders around looking for a protein-rich meal to feed on.   It turns out that Russell Labs is home to plenty of potential food: millions of preserved insect specimens in the Wisconsin Insect Research Collection as well as preserved mammal and bird specimens in the Forestry and Wildlife Ecology wing of the building.

In addition to popping up in weird places, Thylodrias contractus also looks downright bizarre. With the naked eye, an adult female looks more like a bed bug or a small silverfish than a beetle. Technically, the females lack wings and have a larva-like appearance, which is strange in and of itself. Even the males of this species have a peculiar appearance and bear the meekest resemblance to other members of the family. Then there’s the quirky life cycle: developing larvae can go over a year without food. If times are really hard, they can borrow a page from The Curious Case of Benjamin Button and undergo retrogressive molting. With that elasticity in its development, the complete life cycle can vary from several months to several years.

All in all, rather peculiar.

1 Mertins, J. W. 1981. Life History and Morphology of the Odd Beetle, Thylodrias constractus. Ann. Ent. Soc. Am. 74(6): 576-81.

How to Keep Your Mind off the Early Winter

First, daylight savings time ends leaving it dark in the late afternoon.  In the time it takes you to say Catoptrichus frankenhauseri three times quickly, the snowflakes are flying again.  Then there’s the winter driving conditions.  The worst part of it all (from an entomologist’s perspective) is there simply aren’t as many insects to find during the Wisconsin winter.  [Although, I can assure you there are still insects to find if you know where to look. . .Before you know it, the conditions will be just right to look for snow scorpionflies, winter stoneflies, snow fleas and others, but I’ll save that for another time.]

For those that aren’t daydreaming about collecting insects off the frozen tundra, there’s nothing better to get your mind off the flurries outside than thinking about some cool insect cases from this past year (bonus: there’s even green leaves in the images).  One of the prettiest insects that popped up in the lab this summer was the caterpillar of the Funerary Dagger Moth (Acronicta funeralis).  This curious critter is sometimes called a “paddle caterpillar” due to the paddle-like structures that dangle from the jet-black and yellow-spotted body.  Not only is this one of the neatest looking and most distinctive caterpillars out there, but it also has the distinction of gracing the cover of David Wagner’s “Owlet Caterpillars of Eastern North America”, one of the best caterpillar guides available.

Funerary
Funerary Dagger Moth Caterpillar (Acronicta funeralis); Photo credit DZ Johnson

It’s not a very common species, but has been documented from much of the eastern US.  The caterpillars feed on maples and a number of other trees and shrubs.

Funerary Dagger Moth Caterpillar (Acronicta funeralis); Photo credit DZ Johnson
Funerary Dagger Moth Caterpillar (Acronicta funeralis); Photo credit DZ Johnson

 

Identifying Insects by Smell

The title might sound a bit far fetched at first, but it turns out that many insects produce odoriferous chemicals for a variety of reasons.  Stink bugs are a classic example of insects that can produce pungent chemicals, although many related insects in the order Hemiptera also have scent glands.  Many beetles can also produce strong odors when disturbed, and I recently experienced this firsthand after picking up a brilliantly colored Chlaenius ground beetle in my yard.

From my experience, the scents associated with insects aren’t particularly pleasant.  However, exceptions to this observation do exist.  Take the larger yellow ant (Lasius interjectus) for example.  These ants produce a pleasant lemony scent resembling the aroma of citronella candles, hence their other nickname of “citronella ants”.  While there aren’t many cases where an insect can readily be identified by its smell, the citronella ant is probably at the top of the list.

Citronella Ant
Citronella Ant (Lasius interjectus); Photo credit PJ Liesch

Unless you’re flipping over rocks looking for them, you probably won’t bump into citronella ants.  However, they will occasionally nest beneath a concrete slab in a home and end futilely swarming in someone’s basement.  This situation recently presented itself in the lab, and the scent emanating from the ziploc bag gave away the ants’ identity even before I had the specimens under the microscope.

Invasion of the Copper Underwings

An invasion has been going on unnoticed across a portion of the state this summer and early fall.  It all started back in mid-July, when I had several inch-long moths show up at my back deck lights.  I captured a few and set them aside to examine under the microscope but hadn’t thought much of it at the time.  Later, as I was preparing the specimens, I noticed a distinct copper color of the hind wings.  Over the next week, several more of these moths mysteriously appeared in the house. . .

Within days other reports started popping up elsewhere in the state.  By the time October rolled around, I had reports of “home invasions” from over a dozen counties in the southern and western portion of Wisconsin.  The common feature in these cases was the metallic copper color of the hind wings, indicating the Copper Underwing (Amphipyra pyramidoides).  The species is fairly widespread, but isn’t usually encountered in large numbers.  In most cases (mine included) it was only a handful of these moths that snuck indoors. However, in a few situations, the moths were congregating by the hundreds (or even thousands) on homes or garages and were being quite a nuisance.  David Wagner does mention this phenomenon in the Owlet Caterpillars of Eastern North America.

Copper Underwing
Copper Underwing (Amphipyra pyramidoides); Photo credit PJ Liesch

I’m not exactly sure what caused the boom of activity this year, but the caterpillars (commonly called “humped green fruitworms”) must have had perfect conditions to develop earlier in the year.  Luckily, with fall and the cooler weather the invasion seems to have stopped.  Who knows what next year will bring?

Tobacco Hornworm et al.

It’s not unusual for gardeners to find large caterpillars of the Tobacco Hornworm munching on their tomato or pepper plants.  Hornworm caterpillars get their name from the horn-like structure at the back end of the insect and while many species of hornworm caterpillars are known from Wisconsin, the tobacco hornworm is one of the largest and can reach lengths of over 3″.  If all goes well, the caterpillars eventually transform into large, grayish sphinx moths with a series of yellowish dots on the sides of the abdomen.

However, tiny parasitic wasps will sometimes kill a caterpillar before it can turn into an adult moth.  Female Cotesia wasps inject eggs into a tobacco hornworm caterpillar and the developing wasp larvae live as internal parasites.  At a certain point, the wasp larvae have matured and move to the outside of the caterpillar to spin silken cocoons and transform into adult wasps.  Biological control in action!

Hornworm
Tobacco hornworm caterpillar with dozen of cocoons from parasitic wasps. Photo courtesy of Deb Zaring.

Miniature Walking Stick?

Every once in a while I get a report of a miniature “walking stick”.  We do have a few different species of walking sticks in Wisconsin, but the adults are typically 2″ – 3″ long.  We do, however, have some tiny insects called stilt bugs that pop up from time to time during the warmer months.  They’re often seen on flowers but can also be found at porch lights.  I usually find a few each year, although they can often be overlooked due to their small size.

At a quick glance, these insects can resemble small walking sticks but some key differences exist.  First of all, stilt bugs tend to be quite small: usually around 1/2″ long.  Their antennae are also very long with relation to their body and have swollen tips;  the antennae of our walking sticks lack these swollen tips.  A final difference is in the mouthparts of these insects.  Our walking stick species chew on the leaves of oak trees and other plants using mouthparts that function like scissors or pliers.  Stilt bugs consume a liquid diet of plant fluids and have a specialized “straw-like” mouthpart to suck up fluids.  In the image below, the straw-like mouthparts can be seen curling backwards under the body from the head.

Stilt Bug
A stilt bug (Family Berytidae). Photo courtesy of Beth McGrath.

 

Phantom Crane Fly

Many folks are familiar with crane flies, which like to hang around porch lights in the summer and resemble monstrous mosquitoes (luckily, they don’t bite).  From a quick glance, the large insect below generally resembles a crane fly, but has a rather striking coloration to its body.  Is it simply a crane fly dressed up in a tuxedo for a luxurious night out on the town?  Not quite.

It turns out that it’s from a different family of insects called the phantom crane flies.  The particular species in this image is Bittacomorpha clavipes.  Not only does this species have a unique black and white pattern, but segments of the tarsi (“feet”) appear swollen.  These insects occur in the eastern US (including Wisconsin) and are associated with wetlands but aren’t encountered often.

Phantom Crane Fly
The phantom crane fly, Bittacomorpha clavipes. Photo credit: Tyler MacConnell