Site Map Fuzzy Boundaries

by Carl Strang

In the previous post I described my winter project of creating new maps showing all the sites where I have found each singing insect species in the Chicago region. A few of these produced surprises. Take the Texas bush katydid (Scudderia texensis), for instance.

Texas bush katydid

The all-sites map for Texas bush katydids.

The proportion of sites where I have observed this species is noticeably higher west of the Indiana border. Texas bush katydids occur through much of the eastern U.S., but they seem to thin out significantly in the eastern part of this region. I had no idea until I finished this map.

A similar surprise awaited in the maps for long-tailed meadow katydids (Conocephalus attenuatus) and black-sided meadow katydids (C. nigropleurum), two small wetland species.

Long-tailed meadow katydid

Black-sided meadow katydid, one of our most colorful singing insects

The all-sites map for long-tailed meadow katydids.

The all-sites map for black-sided meadow katydids.

As you can see, these are two species I don’t run into very often. What intrigues me is that I have found both only in the northern part of the region. Historically, at least, their ranges have extended well into southern Indiana, but is that still the case? Might these be examples of species losing the southern part of their ranges to climate change? This is one question I don’t think I have enough lifetime left to pursue myself, but perhaps others will be able to show that these species still are around farther south.

A final case for today is that of the tinkling ground cricket (Allonemobius tinnulus).

Tinkling ground cricket. Reddish tones distinguish this woodland-edge species.

Tinkling ground cricket all sites map

Here the map doesn’t tell the whole story. The sites in Indiana and the more southern Illinois counties have lots of tinkling ground crickets. The Cook, Kane and DuPage County sites represent observations of single individuals or, at most, fewer than ten. This seems to point to a drastic thinning northward, and makes the Lake County (Illinois) and Walworth County (Wisconsin) observations seem suspect. But going back to my field notes, I find that the Illinois Beach State Park and Lulu Lake Nature Preserve observations were of large, if isolated populations. What may distinguish them is the sand soil at Illinois Beach and similar gravelly soil at Lulu Lake. In DuPage, Kane and that part of Cook County the soils are clay based. So why haven’t I found tinkling ground crickets on the sandy soils of municipal parks in Wisconsin’s Racine and Kenosha Counties? Scientists love mysteries.

Sarett Nature Center

by Carl Strang

Sarett Nature Center is located in northern Berrien County, Michigan. It has some high quality habitats, in particular a good sized fen and some upland forest. Glimpses of the facility’s education program that I got when I visited there last week pointed to high quality in that service, as well. Sarett’s singing insects provided a couple highlights worth sharing here.

While checking out a restored prairie and its adjacent tree line, I encountered a Forbes’s tree cricket laying eggs.

The female arched her body so as to bring her ovipositor in perpendicular to the sassafras stem. The line of eggs was around 3 inches long.

The female arched her body so as to bring her ovipositor in perpendicular to the sassafras stem. The line of eggs was around 3 inches long.

The fen was rich in sedges and other native plants.

A boardwalk provides access to the fen’s interior.

A boardwalk provides access to the fen’s interior.

Through the SongFinder I heard an unfamiliar insect song, a rapid tapping sound.

The singers proved to be black-sided meadow katydids.

The singers proved to be black-sided meadow katydids.

When I have encountered this species before, its song was overwhelmed by those of black-legged meadow katydids. Those were few in the fen. It became clear that the black-sideds were concentrated in portions of the fen that had coarse-stemmed red-osier dogwoods or broad-leaved cattails.

I left Sarett satisfied with my experience there, but a couple hours of light remained, and the day’s big highlight was still ahead…


Seeking Singers

by Carl Strang

The middle of August through September is the peak singing insect season, and on Tuesday I took the first of a scattered series of vacation days to work on a long checklist of targets. I started with searches of the McKee Marsh edge at Blackwell Forest Preserve, and the area around the bridge over the West Branch of the DuPage River at Winfield Mounds Forest Preserve. My main targets were long-tailed and black-sided meadow katydids. I first found those two species in the county last year, and went to these likely locations in hope of finding more. At Blackwell I found mainly black-legged and short-winged meadow katydids, our two most common species in their respective genera. I also saw a few conehead nymphs like this.

Only about an inch long, and lacking wings, these will have to grow fast to complete their development this season. I suspect they are round-tipped coneheads.

After considerable wading through vegetation depressingly dominated by reed canary grass, I finally spotted a female long-tailed meadow katydid. She did not provide a photo op, but I did post some photos last year from another location.

The Winfield Mounds bridge was on the list thanks to my meeting a photographer who had placed a photo of a black-sided meadow katydid on his website. He said he took the picture at the bridge. Again I found a lot of reed canary grass, but dutifully waded in. Again, plenty of black-legs and short-wingeds, but there were scattered others including a female Say’s trig who hopped onto my net.

I didn’t realize how big the females can get, and how they can have long wing extensions reminiscent of a two-spotted tree cricket’s, until I met this individual. She was a good centimeter long.

Shortly after photographing the trig I spotted a black-sided meadow katydid, and so they indeed persist in that area.

Return to the Dolomite Prairie

by Carl Strang

I needed to return to the dolomite prairie at Waterfall Glen as part of my targeted singing insects search. This had been my dragonfly monitoring area until I switched to surveying the nearby Des Plaines River by kayak, and I hadn’t been in the dolomite prairie for two seasons.

This is a unique environment, arguably the rarest in the county, as it is a prairie growing in a thin soil layer that has developed atop a shelf of Silurian dolomite bedrock in the few thousands of years since the last continental glacier melted away. In my dragonfly monitoring there I had seen federally endangered Hines emeralds hunting a few times. This prairie is not established as a Hines breeding area, though they are known to reproduce nearby. As I walked through the drier part of the prairie depicted above, I noticed some meadow katydids, including this female straight-lanced.

My particular interest, though, was a small area of tall sedges and grasses in the wetter east end of the prairie.

This is where I took the photograph of the female katydid nymph I shared a couple posts ago, the brown one that might have been a black-sided, might have been a long-tailed. Almost immediately as I entered the area I began to see a few black-sided meadow katydids, including this female.

But that wasn’t all. In addition to one of the highest densities of black-legged meadow katydids I’ve ever encountered, I also began to see all-brown individuals including this female.

This was almost certainly a long-tailed meadow katydid. According to one paper I’d read, as of 1983 at least there were no known places where black-sided and long-tailed meadow katydids occurred together. I don’t know whether that has changed in the quarter-century since that publication appeared, but if not then this could well be the first documentation of such a co-occurrence. Considering the potential significance of this find, I went ahead and collected one of the all-brown males, while taking close looks at others like this one.

It proved indeed to be a long-tailed meadow katydid. As I sampled the area with my sweep net I also turned up some colorful individuals like this one.

It has a brown body, and in fact except for the green legs is much like the all brown long-taileds. I was tempted to regard these as variants of the short-winged meadow katydid, a much more common species, because some of them had very bright yellow abdomen tips.

In the end, though, I had to conclude that this was a population of long-tailed meadow katydids with both brown-legged and green-legged individuals. Photos supported the structure of the green-legs’ cerci being closer to long-taileds’ than to short-wingeds’, and while in the literature I could find some references to long-taileds with green legs I could find no mention of short-wingeds with brown bodies.

Thus this small area at the east end of the dolomite prairie, which also is the only part of the whole site where I have seen Hines emeralds hunting, proves to have considerable scientific value. Unfortunately it may be on the verge of being lost. It is smaller than it was even two summers ago, as reed canary grass is invading and displacing the tall sedges and native grasses. I don’t know if anything can be done about this. Herbiciding the reed canary grass probably would also do in the native species, and as I understand it there are no other options. I have to hope the Hines’ can hunt elsewhere, and that these meadow katydid populations will be able to hang on in the marginal habitat with which they will be left if the trend continues.

West Chicago Prairie

by Carl Strang

I had high hopes going into West Chicago Prairie Forest Preserve in my search for new singing insects. It is our largest prairie area in the county with a history of minimal disturbance, and has plenty of low, wet areas that would seem good places for meadow katydids. This late in the season, however, much of the ground is dry, and I was finding few species.

It’s always an interesting place, though. The above scene was highlighted by beautiful flowers of smooth blue aster.

The highlight came as I went through one of the persistent wet spots.

Up jumped a brown meadow katydid, and it paused in the open long enough for me to take a couple photos.

It was not a black-sided meadow katydid, as it was a mature male with an all-brown abdomen. According to my references, habitat and color rule out all but the long-tailed meadow katydid. I wanted to catch him to double-check by taking a look at his cerci, but he got away, and despite much searching he was the only one I saw. According to one published study, black-sided and long-tailed meadow katydids have never been found together. This is puzzling, as their habitat needs on the surface are identical. I must check out areas at Waterfall Glen, where I took this photo a few years ago.

This tiny nymph has an ovipositor mid-way in structure between the two species, and as far as I know could have developed into either one.

Pratts Wayne Woods

by Carl Strang

Pratts Wayne Woods is the largest of DuPage County’s forest preserves. While its 3500 acres have much to offer, the target of my most recent visit was the Brewster Creek Marsh. I had a couple species of meadow katydids in mind that I especially hoped to find there. The part of that marsh I was surveying was adjacent to a dry area where there are high-level equestrian jumping competitions. As I passed through part of that meadow I heard a bush cricket’s short song. It took some minutes to find him, as he took advantage of the light wind moving his perch to keep an edge toward me.

His song was a little ambiguous. I have come to think of the broad-winged bush katydid’s short song as sounding blurred, run together, and composed of more than 3 syllables. The Texas bush katydid usually has a three-syllable short song that sounds, to my ear, crisp and articulated: dig-a-dig! I needed to take the time to find this individual because his short song had 3 syllables but sounded slurred together.

The wing proportions alone say Texas bush katydid, but to be sure I caught him and photographed his tail plate, confirming the ID. Now it seems I will have to find a few more and confirm that it’s the syllable count rather than the crispness that matters in separating these two species. Soon thereafter I found myself in a wet area dense with tall sedges in northern Brewster Creek Marsh.

It was disappointing, however. There was essentially nothing to be found out in the sedge area, and just a few black-legged and short-winged meadow katydids singing along the edge. I moved west to a grassy area at the edge of a large pond. As I stepped out of the woods into that grass I caught a flash of golden brown as a slender jumper got out of my way. My immediate hope was fulfilled when a close look proved the insect to be one of my target species, a male black-sided meadow katydid.

This was the best photo I got of a male. The abdomen is mainly a shiny black in color. I saw several males, and also a female.

She easily is the most colorful small meadow katydid I have seen, and would vie with the male black-leg (a large meadow katydid) as the local show winners for subfamily Conocephalinae.

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