Category Archives: Big Bugs

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!

 

Buckets of Beetles

Many naturalists will relate to this post: as nature enthusiasts, everyday tasks sometimes end up taking much longer than expected due to fascinating biological distractions just beneath our feet.

As I was mowing the front lawn over Memorial Day weekend, I stumbled upon a prehistoric-looking stag beetle, which is always a neat creature to come upon.  As an entomologist, my first instinct was to pick it up to make a closer examination.  Typically, I run into stag beetles a few times each year and it’s usually the large, “reddish brown stag beetle”: Lucanus capreolus (see image below).  The beetle I found was a bit smaller, darker, and lacked the bicolored legs of L. capreolus, but was still a good-sized insect at over an inch long.  After a beverage break and some Internet browsing, I figured I must have been looking at the closely related Lucanus placidus.  Interesting, I thought, and placed the stag beetle back on a portion of the lawn that had already been mowed, lest it face the wrath of a metallic tornado.

At roughyl 2 inches long, the "reddish brown stag beetle" (Lucanus capreolus) is amongst our largest beetles in Wisconsin. Photo Credit: PJ Liesch, UW-Entomology
At roughly two inches long, the “reddish brown stag beetle” (Lucanus capreolus) is amongst our largest beetles in Wisconsin. Photo Credit: PJ Liesch, UW-Entomology

Another pass or two with the mower and I spotted a few more stag beetles.  I was no longer simply stumbling upon these beetles—something else must be going on.  Once again, I stopped mowing to take a closer peek in the taller grass, only to find even more beetles.  Within the span of five minutes, I had found nearly forty stag beetles in the lawn near a low spot where a tree must have previously stood.  As with the first specimen, I gently relocated these beetles and rushed to finish mowing in the dwindling light.

Around 10:30 PM, I wandered back outside with a flashlight to see what the beetle situation looked like.  I had no idea what I was about to stumble upon—hundreds of battling stag beetles!  Male stag beetles use their large mandibles to compete for females, which made my front lawn seem like a combination of the Bachelorette mixed with Gladiator.  It was astonishing to see the sheer numbers of stag beetles present in a single spot at a given time.  In an attempt to count them, I starting placing them into an empty flower pot.  The forty I had spotted earlier seemed like a drop in the bucket—quite literally!  The bucket was nearly full to the brim with 250 beetles, and I eventually stopped counting.  I’d estimate that I spotted nearly 400 stag beetles in a single night.

A handful of battling stage beetles. Photo credit: PJ Liesch, UW Entomology.
A handful of battling stage beetles. Photo credit: PJ Liesch, UW Entomology.

I did eventually confirm that the species of stag beetle in the lawn was Lucanus placidus.  According to the scientific literature, aggregations have been noticed in lawns on occasion.  In Kriska and Young’s “Annotated Checklist of Wisconsin Scarabaeoidea” (2002) an aggregation of 15 males and females was once noted beneath a black oak tree in the state.   I’m not entirely sure what kind of tree used to occupy the low spot in my front lawn, but the stag beetles obviously loved it (note: stag beetle larvae live in decaying wood).  As an interesting side note, the same low spot was also home to the “Dead Man’s Fingers” fungus (Xylaria polymorpha), another biological curiosity in its own right.

It’s amazing what you can find in your own back yard or front lawn if you take the time to look!

The “Killers” on Campus

The things entomologists do for the sake of their curiosity:

This past Wednesday I found myself thinking about Hollywood Horror Films while crouched along a hot sunny rock wall on the UW-Madison campus patiently waiting for one of our largest wasps to land mere inches from my face. What gives?  Cicada Killers: One part cold-blooded killer, one part flying teddy bear (check out how fuzzy that thorax is!).

Cicada Killer 2_opt
Cicada killer wasp (Sphecius speciousus) on the UW-Madison campus. Photo credit: PJ Liesch, UW-Entomology

Part of their basic biology plays out like a B-Class horror movie: a victim is injected with an incapacitating chemical before being dragged to an underground lair and left to be eaten alive. While it sounds bizarre, this is actually fairly common in the insect world and there are many examples of wasps that paralyze their prey and haul them off to their nests in the ground to feed to their young.  (One of my favorites is the Zombie-making “emerald cockroach wasp“)

At nearly two inches long, cicada killer wasps (Sphecius speciousus) are amongst our largest wasps in Wisconsin and resemble large yellowjackets. They specialize in tracking down and attacking cicadas, which the females haul back to the nests they had previously dug in patches of bare soil. Despite their “killer” habits, these insects are usually quite docile and non-aggressive towards humans. Unlike their smaller yellowjacket cousins which have a large colony to defend, cicada killers are solitary nesters. You can actually get within inches of them without provocation, although the territorial males may fly around to check you out.

CIcada Killer
Territorial male cicada killer wasp trying to stare me down for getting too close to his rock. Photo credit: PJ Liesch, UW-Entomology [Click for a larger image]
Cicada killers can be common in the state and also happen to be common on the UW-Madison campus. You can often find them near some of the dorms along the Lakeshore bike path and also in the rock wall along the Linden Drive pull-off near the Nutritional Sciences Building (just in case you’re in the mood to meet them up-close and personal.)

In the mood for an actual horror movie involving giant predatory wasps? The recently released “Stung” might be perfect for you. . .

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.