A Not-So-Silent Grasshopper

by Carl Strang

Until a couple weeks ago, the grasshoppers that drew my interest belonged to two subfamilies, the band-winged grasshoppers and the stridulating slant-faced grasshoppers. The former have displays in which they rattle their wings in flight (crepitation), and the latter produce sounds by scraping their folded wings with their hind legs (stridulation). There is an additional small subfamily known as the silent slant-faced grasshoppers. Structurally they resemble the stridulating ones in having faces that slant back distinctly from the tips of their heads, but they lack the minute pegs needed to produce the stridulating sounds.

I had encountered one of the members of this non-stridulating subfamily, the clipped-wing grasshopper, a few times in Indiana marshes.

Here is a female I photographed a couple years ago in Fulton County, Indiana. The slanting face is clear, as is the distinctive wing-end profile which gives the species its common name.

Here is a female I photographed a couple years ago in Fulton County, Indiana. The slanting face is clear, as is the distinctive wing-end profile which gives the species its common name.

On a recent visit to the Houghton Lake Nature Conservancy site in Marshall County, Indiana, I encountered a cluster of these insects in a little marsh meadow. I started hearing buzzing sounds, and was surprised to find that these were being produced by male clipped-wing grasshoppers.

One of the Houghton Lake males.

One of the Houghton Lake males.

They were behaving just like band-winged grasshoppers. Sometimes they crepitated when flushed, but they also were producing the rattling sounds in undisturbed display flights. They also can fly without crepitating. Their buzzes had the same loud, crackling quality as, say, a seaside grasshopper from the band-winged subfamily.

Looking back at the literature, I see that Richard Alexander included this subfamily in his list of Michigan singing insects, and so this is no new discovery. I wonder if the few species in this subfamily started out as stridulators that also could crepitate, and over time were selected to emphasize the latter display, then having ruled out stridulation lost the ability to perform it.

 

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Hypothetical Cicadas and Grasshoppers

by Carl Strang

Thanks to two publications, one very new and one very old, I have been able to fill out my list of singing insects that may occur in the Chicago region by adding possible cicada and grasshopper species. The new reference is a monograph published last year by the Entomological Society of America, The Cicadas (Hemiptera: Cicadoidea: Cicadidae) of North America North of Mexico, by Allen F. Sanborn and Maxine S. Heath. There is not a lot of natural history information in it, as its focus is on sorting out species and their relationships, but it is complete in its species coverage and at least outlines the range for each. It allowed me to add three possible cicadas to my list. Two of them are tallgrass prairie specialists that are known in Illinois but may not occur this far north: the common grass cicada (Cicadetta calliope), a tiny early season species, and the bush cicada (Tibicen dorsatus), a late season species. The third added cicada, Walker’s cicada (Tibicen pronotalis), is a large insect of woodlands along streams.

The old reference is W.S. Blatchley’s Orthoptera of Northeastern America with Especial Reference to the Faunas, of Indiana and Florida. This one was published back in 1920, and is available as a 2012 reprint by the Forgotten Books company. The text is generally readable, but somewhat faint. The taxonomy and nomenclature for the grasshoppers have been remarkably stable over time, and most scientific names haven’t changed. I was able to make the necessary updates by referring to the most recent popular guide to grasshoppers, katydids and crickets by Capinera, Scott, and Walker. Blatchley’s book contains considerable natural history information, and is reminiscent of the Bent’s Life Histories of Birds in its style.

There are two subfamilies of singing grasshoppers. The stridulating slantfaced grasshoppers, subfamily Gomphocerinae, sing while perched or resting on the ground, lifting and lowering their back legs to rub them against the wings, producing a rapid zuzz-zuzz-zuzz sound that is distinct from other insect songs, but to my ear this stridulation seems much the same in different species. The only one for which I have a photograph is a northern species.

Thomas’s broad-winged grasshopper at Whitefish Point on the Upper Peninsula of Michigan.

Thomas’s broad-winged grasshopper at Whitefish Point on the Upper Peninsula of Michigan.

That grasshopper does not occur as far south as our area, but another member of its genus, the sprinkled broad-winged grasshopper (Chloealtis conspersa) is one I’ll listen for, along with 7 other candidates in this subfamily. Though their songs probably are much the same, their habitats and details of their appearance are different.

The other singing subfamily of grasshoppers is Oedipodinae, the band-winged grasshoppers. These produce their sounds in a different way, crepitation, by rattling or rubbing together their wings in flight. The potential additions to the local list number a dozen species. One of these also was prominent at Whitefish Point.

A pair of clear-winged grasshoppers, Camnula pellucida

A pair of clear-winged grasshoppers, Camnula pellucida

The literature suggests more variation in the sounds produced by the crepitation method, but these grasshoppers are flying when they sing, and so should be easier to locate.

Singing Insect Season Begins

by Carl Strang

In northeast Illinois there is a single insect species that each year is the first to produce a sound display audible to human beings. That is the greenstriped grasshopper, Chortophaga viridifasciata, one of the few singing grasshoppers we have in our area.

Greenstriped grasshopper male

Male grasshoppers produce songs in two ways. Some species rub their folded wings with their legs, emitting a zuzzuzzuzz… sound. This is called stridulation. Others, including the greenstriped grasshopper, perform short display flights in which they produce a rattling or crackling sound with their wings (crepitation). In the case of the greenstriped, the sound is a soft buzz or rattle, easy to miss if you are not listening for it. The fact that it is a display is demonstrated by the fact that grasshoppers flying to escape possible predation do so silently.

Greenstriped grasshopper females are grass green, in contrast with the slightly smaller brown males.

The first observed song date in this species is important to me personally, because singing insects are my main research focus. That date this year was April 3, and I heard several different individuals displaying that day. As I begin my 7th year of field study, this is by far the earliest start. The next two earliest were April 20 in 2010, and April 28 in 2006. The mild winter and warm spring got food plants growing early, and the overwintering grasshopper nymphs were able to complete their development in short order. I won’t be surprised to find a number of records for earliest song dates set by other singing insect species in the coming season.

Singing Insects at Whitefish Point

by Carl Strang

The third goal of my Upper Peninsula trip last week was to study the singing insects there. Compared to northern Illinois, the singing insect fauna was very limited. At night the campground at Tahquamenon Falls State Park was quiet, except for the amazing snoring of one of my neighbors, thankfully only for one night. During the day the principal singing insect in the forest was the dog-day cicada.

Open areas such as Whitefish Point had more to offer. I was especially pleased to find that gray ground crickets are common there. Like all ground crickets these stayed well hidden. Here is typical habitat.

Gray ground cricket habitat b

This species is known from dunes areas around southern Lake Michigan, but the only time I was at Illinois Beach State Park listening for them was a windy day and I could not hear them clearly. At Whitefish Point I easily distinguished their song. Though the trills seem composed of discrete notes like those of Allard’s ground cricket, they are at least three times faster (Allard’s were there as well, making comparison easy). Also, the trills were not continuous but rather were interrupted by brief pauses that were spaced regularly in some individuals but at varying intervals in others. In addition to Allard’s, familiar crickets at Whitefish Point were fall field crickets and Carolina ground crickets.

Whitefish Point also was home to two singing grasshoppers that represented the two forms of grasshopper song production. One of them was a crepitating species like Illinois’ greenstriped grasshopper. My references point to the clearwinged grasshopper, Camnula pellucida, as the identification, though I am not certain.

Clearwinged grasshopper 2b

In the photo the male is on the left. Crepitation is sound production by the rattling or snapping of the wings in flight. In this species the rattle is much louder than that of the greenstriped grasshopper. Clearwinged grasshoppers occupied the more open dunes areas. The other form of sound production is called stridulation. A common grasshopper that stayed close to woody plants at Whitefish Point produced loud “zuzz-zuzz-zuzz” sounds with this method. My best stab at identification is Thomas’s broad-winged grasshopper, Chloealtis abdominalis.

Thomas's broad-winged grasshopper 3b

The black areas on the sides of the pronotum seem to point to that species. Another photo, taken just as the grasshopper turned to put some distance between itself and my camera, shows that from behind the legs have a lot of red on them.

Thomas's broad-winged grasshopper 5b

In stridulation, both legs are lifted and lowered at once, and rows of pegs on them rub against the folded wings to produce the sound.

I also found broad-winged bush katydids at Whitefish Point, but I will hold that discussion for a later time.

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