Category Archives: Uncommon Insects

The Stories that Insects Tell

Imagine taking an American history class where many of the important events were reduced to mere footnotes or skimmed over entirely.  Anyone taking the class would be shocked at this notion—I mean, the Civil War was a big deal after all!  When you look at a different field of study—biology—such a trend has surprisingly occurred, with insects getting the short end of the stick.  Insects are the most diverse and abundant animals on the planet and make up roughly 70% of the 1,000,000+ described animal species.  Yet, many introductory biology textbooks skim over insects (and invertebrates in general) in favor of more charismatic megafauna—a trend that has only gotten worse over time.  Insects may be small, but they serve crucial roles in the world around us from pollinating plants to serving as the base of food webs.  Appropriately, E.O. Wilson referred to insects as “the little things that run the world” in his famous call for their conservation.  It’s difficult to conserve these little creatures that run the world when so few people really get to know them.  

With their sheer diversity and abundance,  knowing the insects also helps us better understand the world, and everyday life, around us.  Getting to know the many different insects is a bit like learning a foreign language.  Travel to an exotic country where you don’t speak the local tongue and you’d have a hard time understanding the everyday happenings around you.  As you picked up words and phrases of that foreign language, things will become easier to understand.  Along these lines, if you can recognize the insects around you, it helps interpret the stories they tell.  Truly knowing your insects is like possessing an all-powerful decoder ring to the untold stories that surround us.  

Let’s look to flies to illustrate this point.  To many folks, a small fly found in their home is assumed to be a fruit fly, and a large fly, a house fly.  But there are dozens of different flies that commonly show up indoors—each with their own story to tell.  Fungus gnats hint at overwatered houseplants, moth flies indicate build-up in a bathtub drain, and metallic blow flies can alert you to a mouse trap in need of checking.  Outdoors, other species of flies can provide clues that gauge water quality, indicate the presence of specific plants, or solve crimesbut only if one knows how to interpret their clues.  If a picture is worth a thousand words, I’d argue that a properly identified insect is worth even more.  

The unusual fly species, Asteia baeta. At only 2mm long, these flies can readily be mistaken for fruit flies to the naked eye. Photo Credit: PJ Liesch, UW Insect Diagnostic Lab

This holiday season, my own love of insects led to a scientific discovery that would have gone unrecognized in most households.  A day after setting up our “real” Christmas tree, I noticed several tiny flies at the windows of our home.  My curiosity was piqued and like any good detective, some sleuthing was needed.  I recall an undergraduate professor telling the class, “a biologist without a notebook is off duty” to which I’d add, “an entomologist without vials is off duty”.  So now I was off, vials in hand, on an insect hunt in my own house.  Once the specimens were examined under the microscope, I recognized the flies as a rare species (Asteia baeta) from the poorly-known family Asteiidae.  There isn’t much written about these flies, but they’re known to be associated with fungi, vegetation, and tree sap, which told me that the new Christmas tree was the source.  These flies have only been spotted in Wisconsin a few times and no preserved specimens exist for that family in the Wisconsin Insect Research Collection (I’ll be donating some soon).  Looks like our Christmas tree came with it’s own entomological story to tell this year—I’m glad I knew how to listen.

The source of the unusual flies—apparently our cat wanted to try and hunt for them as well. Photo Credit: PJ Liesch

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!

 

A Mysterious Tingling Sensation: Bird Mites

If I had to pick the most misunderstood creature I regularly encounter at the diagnostic lab, it’d be bird mites.  Perhaps you’ve never even heard of bird mites—tiny arachnids that suck the blood of the birds nesting in your back yard.  Under the right conditions, those same mites can wander indoors and  inadvertently bite humans.

If you haven’t heard of bird mites before, your first inclination may be to do a quick Google search to learn more.  Unfortunately, the Internet is rife with misinformation about these creatures.  In the age of fake news, here’s another gentle reminder to assess the credibility of online sources.  I’ve encountered websites full of misleading, downright wrong, and in some cases, dangerous management recommendations about bird mites.  I’ve also had to console clients on multiple occasions because they’ve read about bird mites online—only to believe that the mites will be infesting themselves, their homes, and vehicles indefinitely.

Although small (<1 mm long), bird mites can be seen with the naked eye, and their nearly constant movement helps give them away.  Perhaps the best description of their appearance is walking flakes of pepper.  Under magnification, bird mites have a somewhat tick-like appearance with their eight legs and long, prominent mouthparts.  The mites are often whitish in color with some black on the body but can turn darker after feeding.   Each year, I typically bump into 10-20 bird mite cases during the spring and summer months.  The mites can actually be quite common but simply aren’t encountered unless you have a bird nest very close at hand: under a back deck, on a patio light fixture, in a gutter or a damaged soffit area or in a shrub just outside a bedroom window.

Bird mite. Photo Credit: Whitney Cranshaw, Bugwood.org

True to their name, bird mites are parasites that feed on the blood of birds.  These mites are often most noticeable when young birds have just left the nest and the mites wander desperately looking for a blood meal.  Without their avian host, bird mites have a short time to live, but they can make their way indoors where they can crawl on and inadvertently try biting humans and pets.  Although the mites can be an itchy tingly nuisance, they can’t survive on humans or in homes for any significant length of time.  The literature suggests that off of their avian hosts, the common bird mites may be able to survive a matter of weeks under the most ideal of conditions.  In most cases, the conditions off the birds are so hostile (too dry) that survival is limited to a few days at best—especially in a modern home with air conditioning.

As with many pest control situations, eliminating the source of the problem often brings about rapid results and bird mites aren’t any different.  If you’ve found bird mites, removal of the bird nest once the birds have left the nest is the single most important step.  Like flipping a switch, mite activity typically drops off rapidly within a day or two of the nest being removed.  Indoors, desiccation is probably the biggest threat to bird mites, so running your AC and/or dehumidifier may  help hasten their demise.  Vacuuming, using sticky tape, or wiping up mites with a damp soapy cloth can all help eliminate any additional stragglers that made it indoors.  Pest control professionals typically also apply to residual product to nearby areas to help control any residual mites.

Feeling itchy yet? 

The Case of the Hitchhiking Bog Wasps

While most of the cases at the Insect Diagnostic Lab involve fairly common insects, I do also see my fair share of unusual cases each year. One of my favorites from 2015 involved a miniature “bog wasp” from the family Eucharitidae: Pseudochalcura gibbosa. Due to their small size, these tiny (~2 mm long) wasps would simply go unnoticed in most cases––that and the fact that you’d most likely have to be wandering around in a bog to find them. So how exactly did these tiny, easily-overlooked “bog wasps” end up being submitted to the Insect Diagnostic Lab?  Simple: a homeowner found several in a second story bedroom of their house. This simply didn’t make much sense, so I knew there must have been a deeper story at play. Whenever I get an unusual case like this in the diagnostic lab, I often have to track down additional pieces of the puzzle before things make sense.

Bog Wasp-Pseudochalcura gibbosa
The tiny, hump-backed wasp: Pseudochalcura gibbosa. Photo Credit: PJ Liesch, UW-Entomology.

In this case, this particular home was located near Rhinelander, Wisconsin, where there’s certainly an abundance of bogs. As part of their life cycle, the females of Pseudochalcura gibbosa lay eggs on Bog Labrador Tea (Ledum groenlandicum), a common shrubby plant in northern bogs. The eggs spend the winter on the plants and hatch the following spring. However, these wasps aren’t plant feeders, and their presence on Labrador Tea is temporary. What they’re really after are immature carpenter ants (Camponotus sp.) to feed on. After the eggs of Pseudochalcura gibbosa hatch, it’s thought that the wasp larvae hitch a ride on foraging carpenter ant workers back to their nest. Once they’ve dropped off their six-legged taxis in the ant nest, the tiny larvae of Pseudochalcura gibbosa behave much like a wood tick on a dog: they hang off of and feed on carpenter ant larvae and pupae. In some cases, dozens of small wasp larvae may be present on a single carpenter ant larva. Eventually the tiny wasps complete their development and leave the carpenter ant nest to head back to the bog.

Having identified the wasps as Pseudochalcura gibbosa, I was suspicious that a carpenter ant nest was also present in the home and simply hadn’t been found yet. After some detective work, the homeowner eventually confirmed the presence of carpenter ants in the house. With that final piece of the puzzle I had my explanation for how the wasps had hitchhiked from a nearby bog to an upper story bedroom: it’s was all the ants!

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.

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.

Elderberry Borer

A recent image came in to the lab from the Wausau area of an adult elderberry borer (Desmocerus palliatus).  It gets its name from the larval stage which lives inside the stems of elderberry plants and bores down to the roots.  These beetles are members of the long-horned beetle family (Cerambycidae) due to their long antennae.  The elderberry borer happens to be one of our most distinctive species, although it isn’t spotted often.  It was even featured many years ago on a 33 cent US postal stamp.

Elderberry borer (Desmocerus palliatus). Photo courtesy of Chuck Frank.
Elderberry borer (Desmocerus palliatus). Photo courtesy of Chuck Frank.

Goldsmith Beetle

One of my favorite submissions to the lab came in recently from Waupaca County, WI.  The species is known as the Goldsmith Beetle (Cotalpa lonigera).  It resembles a large May/June Beetle or the Grapevine Beetle.  The neat thing about this particular species is the brilliant metallic, golden color of the head and pronotum, which reminds me of the scarabs of ancient Egyptian lore.  It’s an uncommon species known from the eastern half of North America, and is apparently associated with woodlands.

Goldsmith Beetle (Cotalpa lanigera). Photo courtesy of Ken Erickson.
Goldsmith Beetle (Cotalpa lanigera).  Photo courtesy of Ken Erickson.