All posts by pliesch

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 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!

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

Rabbit Bot Fly

One of those unusual insects that seems like something out of a science fiction movie is a bot fly.  These insects are parasites of other animals, where they live beneath the skin as larvae.  There are a number of species out there that affect large mammals such as cattle, sheep, and caribou.  There’s also a species called the human bot fly (Dermatobia hominis), which is known from tropical locations.  Around Wisconsin, we have some species in the genus Cuterebra that attack rodents and rabbits.  As adults, the rabbit bot flies resemble large, black and white bees with red spots on their eyes.  They’re rarely seen, but a photograph recently came in from Madison, WI.

Rabbit Bot Fly_opt
One of the elusive Rabbit Bot Flies. Photo courtesy of Quentin Sprengelmeyer.

Eastern Dobsonfly

Like deer hunters going years without seeing that one “big buck”, entomologists have their own, albeit smaller, trophy to chase after: a male eastern dobsonfly (Corydalus cornutus).  Males of this species have intimidatingly large mandibles, which can be over an inch long.  I’ve never seen one live myself, but have had several pictures come in to the diagnostic lab this summer.  The larvae (called hellgrammites) live in fast moving rivers and streams.  The adults are strong fliers and can be attracted to lights at night.

Eastern Dobsonfly_opt
Eastern Dobsonfly (male). Photo courtesy of Karen Vornholt.


It’s a fly, it’s a wasp, it’s a bee?. . .

One of the most unusual bees I’ve ever seen was brought in by our fruit crop entomologist earlier today.  Its behavior had been described as somewhat “fly-like”, although the abdomen had a color pattern that screamed “yellowjacket”.  It was hairy like most bees, but possessed some unusual hook-like appendages from the tip of the abdomen.  After some digging, I was able to identify the species as Anthidium manicatum, commonly known as the “European wool-carder bee”.  It happens to be a European species that was introduced to the US back in the 60’s and is now widespread. The species gets its name because females collect hair-like fibers from plants to line their nests.

Anthidium manicatum, the "European wool carder bee"
Anthidium manicatum, the “European wool-carder bee”. Photo credit: PJ Liesch


Japanese Beetle Season

It’s that time of the year again.  Much to the dismay of gardeners and landscapers in Wisconsin, the first reports of Japanese Beetle adults came in last week from the La Crosse area.  Additional reports from Dane, Racine, Sauk, and Rock counties have trickled in over the last few days.  Despite the deep frosts reported last winter, the soil-dwelling grubs managed to survive just fine and the adults are popping out as if it were a typical year.  Based on our history in the state, we’ll likely be seeing the Japanese beetles until early September.

Japanese Beetle Adults
Japanese beetle adults on turfgrass; Photo credit PJ Liesch