Meadow Tree Crickets

by Carl Strang

Some tree crickets live in trees, others live among the trees in the forest understory, but there are a few species that inhabit meadow and prairie areas. Last week I looked at some of these when I did some sweep sampling in two locations. The first was Springbrook Prairie Forest Preserve.

This low area dominated by big bluestem grass was part of the habitat I surveyed.

I went there in hope of finding more of the cicadas, tentatively identified as swamp cicadas, that I heard there last year. At the time the song seemed definitive, but I since have learned that Linne’s cicadas sometimes have songs that are similar, and so I was hoping to find one to photograph. All was quiet, however. That’s not necessarily a bad sign. If this is indeed a new population (DuPage is north of the published range for swamp cicadas), they might not be emerging every year. In any case, while I was waiting for singing cicadas I did some sweep sampling, and turned up several tree crickets.

Here is one of the individuals I caught in a goldenrod-dominated area. It has a dark stripe down the top of the head and pronotum, as well as dark antennae. Despite the otherwise pale color, these features point to the black-horned/Forbes’s pair of tree cricket sibling species.

Proper identification of these tree crickets requires an examination of spotting on the basal two antenna segments.

Here the spots on the first, basal segment are very large and smudged. Those on the second segment likewise, to the point where the entire segment looks black at first glance. Also note the dark area on the underside of this tree cricket’s abdomen. All these features point to black-horned/Forbes’s.

The next cricket, from the big bluestem area, is much paler, and shows a different antennal spot pattern.

Here the spots all are smaller, and the outer ones on the basal segments are round and have smeared edges. This is a four-spotted tree cricket.

Another Springbrook tree cricket was more ambiguous.

This individual happily nibbling my finger shows spotting that falls within the range of overlap for four-spotted and black-horned/Forbes’s tree crickets. The most definitive spot is the outer one on the basal segment. It appears just large enough to rule out four-spotted.

The next day I did some sweep sampling at Mayslake Forest Preserve.

The sample included several pale tree crickets like this.

The cricket in that last photo had the following spot pattern.

This is a clear indicator of four-spotted tree cricket, the outer spots on both segments small, round, and faded looking.

A final example showed even fainter spots.

Again I identified this one as a four-spotted tree cricket.

There is a fourth meadow species that I have been watching for but so far have not found. The prairie tree cricket is generally pale, like the four-spotted. Its antenna spots are heavy and close together, but without the blurred smudging of the black-horned/Forbes’s species pair.

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Sphagnum Ground Cricket

by Carl Strang

The sphagnum ground cricket was a species I had sought but failed to find in DuPage County last year. Apparently low vernal pool areas in our woodlands are not sufficiently close to the sphagnum habitat the species requires, and as we have no sphagnum in DuPage I would need to look elsewhere. When my plans for Illinois Beach State Park were thwarted by the south unit’s closure, I decided to move on from the north unit (where I had been successful in my search for gray ground crickets) to Volo Bog State Natural Area.

This is the center of the main bog, accessible by a well maintained boardwalk.

The outermost zone of the bog was not promising. There was no sphagnum that I could see, mainly marsh plants, with the prominent singing insects being black-legged meadow katydids and Carolina ground crickets.

Here is the marsh habitat, with the next, shrubby zone in the background.

As I entered the next concentric ring of habitat, working my way toward the bog’s center, a mix of shrubs was dominant. The black-legs and Carolinas petered out. I began to see sphagnum moss.

The shrub and sphagnum habitat at Volo Bog.

At first I heard mainly Say’s trigs, but it seemed there was something else. I got out the SongFinder, and its frequency-lowering function allowed me to identify a second, fainter, more rapid trill. When I then removed the headphones I found that I could pick out the second trill, which matched my memory of reference recordings of sphagnum ground crickets. I got down on my hands and knees at the edge of the  boardwalk, probing the sphagnum lightly with my fingers, and that was all it took to get some photo ops.

This nymph was the first sphagnum ground cricket I saw. I was struck by its beautiful coloration, especially the mottling and white dots on the hind legs.

Adults seemed mainly black.

The mottling is subdued on the legs, but still present on this adult. The eyes are large and brown.

There were so many singing at once that I was not able to pick out the ends of any trills. The song seems very like that of the gray ground cricket, but fainter, being a very rapid, level, high-pitched trill (more rapid than those of Allard’s ground crickets or Say’s trigs). I am guessing that the gray ground cricket needs to be louder in its more open, wind-swept dune habitat.

Gray Ground Cricket

by Carl Strang

The south unit of Illinois Beach State Park is closed. I found that out when I arrived there, having taken a vacation day and driven the hour and a half or so it takes to reach Zion. That squelched singing insect research Plan A, though it turned out for the best, as we’ll see. I would not be able to achieve all my goals, but I could at least try to find gray ground crickets at the north unit.

Grassy area just inland from the beach at Illinois Beach State Park’s north unit.

Between the parking lot and Lake Michigan, this grassy area is protected enough from wind and waves to support tall prairie grasses including big and little bluestem, and Indian grass, as well as a few forbs. The soil appears to be nearly pure sand. All I was hearing at the parking lot were some fall field crickets and Allard’s ground crickets, but I followed a path toward the beach and soon, in the sandy prairie shown in the photo, was hearing scattered gray ground crickets. I kept hoping I might see one out on the path, but no such luck, and I didn’t want to be too intrusive at an area that already gets much use. I’ll hope for a photo opportunity some other time.

The gray ground cricket’s song is distinctive, though in part that is because of the connection to the habitat. There was one place where an Allard’s was singing close enough to a gray to allow a direct comparison. Both ground crickets have long trills, but that of Allard’s is noticeably slower, the individual notes fully distinguishable if a little too rapid to count. The gray ground cricket’s trill is much more rapid, though still audibly composed of distinct notes (i.e. they don’t blend into a single tone). The song is higher pitched than that of Allard’s. In addition, the gray incorporates characteristic pauses here and there. A recording can be found on-line here.

It was only mid-day, so I decided to check another Lake County site on my fall research list, which I had thought would have to happen on another day. I’ll report on that tomorrow.

Added Grasses

by Carl Strang

Yesterday I shared some newfound insects on Mayslake Forest Preserve. Today I want to add a couple new grasses. This large one is growing in a couple spots near the edge of May’s Lake.

It proved to be relatively easy to identify: purpletop,Triodia flava.

The other added species is scattered through the savannas. It keys to woodland brome.

Woodland brome should be done flowering by now, but apparently the late season continues to influence some species.

The purplish color of the purpletop’s spikelets, and the graceful drooping spread of the woodland brome, demonstrate that grasses can be beautiful.

Added Insects

by Carl Strang

It’s fun to discover new things, and at Mayslake Forest Preserve I continue to add new species of insects or plants almost daily in the summer. This week the most recent added insect was the question mark butterfly.

This species is named for the tiny silvery markings on the hind wings.

Last week this moth appeared, and I’ve seen another since.

The yellow-collared scape moth is a smaller relative of the similar looking Virginia ctenucha.

An abundant visitor of flowers in the stream corridor prairie this summer has been the great black wasp.

This solitary species digs tunnels, where it places katydids and grasshoppers for its young to eat.

A final new species remains to be identified.

One of the biggest weevils I’ve ever seen, this interesting looking insect turned up in one of the kids’ sweep nets on Take Your Kids to Work Day.

Of course, it’s also enjoyable to see familiar insects.

The wild indigo dusky wing is one of our more common skippers. I have seen them hanging around wild indigo plants at Mayslake, but their caterpillars also feed on other legumes.

Lately I’ve been seeing scattered slender spreadwings.

The pale vein at the tip of the wing, as well as the dark abdomen tip on this male, are distinguishing features.

Two bluets appeared to be large enough, and matching the correct color pattern, to identify as familiar bluets. First was a male.

The violet color seemed odd.

Later a female appeared.

She was feeding on another damselfly, which appeared to be a newly emerged forktail.

I owe thanks to Linda Padera, who accompanied me on a lunch break walk and spotted some of these insects.

Scab Plants

by Carl Strang

On Friday I went up to the former friary site at Mayslake Forest Preserve to check on the progress of plant growth there. Most prominent were a number of weeds, some of which already were flowering. I was pleased to see my tentative identification of barnyard grass proved out.

For such a relatively large-bodied, coarse plant, this grass proved its ability to grow rapidly and in large numbers on a site that had been bare soil a short time earlier.

The other dominant species was velvetleaf, though none of those I saw were flowering yet.

This import from India is one of the earliest weeds to appear in sterile-looking soils.

A very few crabgrass plants also were present, along with a few quick-growing nut sedges.

These proved to be an annual species I had not observed previously at Mayslake: the rusty nut sedge.

Other plants also were additions to the preserve list.

This one is called flower-of-an-hour because of the ephemeral nature of its blooms.

Another new one was the green amaranth.

Amaranths sometimes were cultivated by Native Americans in their early agricultural period.

It’s easy to disparage such weedy species, but I found myself remembering how Tom Brown calls them “scab plants.” They grow quickly, protecting the wounded soil and sequestering carbon and minerals until giving way to more competitive perennials. I’m looking forward to seeing the longer-term native plants that were seeded here.

Stripes

by Carl Strang

Identifying species of small meadow katydids (genus Conocephalus), especially nymphs, can be challenging. Most adults are readily sorted out, especially males if you can get a good look at the cerci or claspers at the tips of their abdomens.  Females are trickier, but their ovipositors often allow distinctions to be made. I’ve decided to take a shotgun approach in my survey at Mayslake Forest Preserve, sweep sampling on a weekly basis and taking photos of as many individuals as I can. Last week I noticed something that is potentially helpful.

This is an unambiguous male short-winged meadow katydid. Cerci are right, lots of orange color around the abdomen tip, short wings, small size.

As I compared my many photos, I found that the color pattern on the sides of the hind femurs drew my eye. Notice the band of clear green color bounded by brown stripes on either side. Here’s a female, again clearly a short-winged.

Though she may be an instar short of adulthood, this one has the ovipositor of a short-winged.

Again the color pattern on the femur appears. I did an Internet search, and except for some photos from Texas, short-winged meadow katydids show this striping pattern across eastern North America. Then I began to compare other species. I started with another familiar one, the slender meadow katydid.

This male I photographed last year has clear green femurs, without the stripes.

Again an Internet and reference book search showed consistently clear green femurs on this species. However, I was surprised to find that a female I had identified a couple years ago as a slender meadow katydid had the femur stripes.

The long wings fooled me. The ovipositor actually rules out slender meadow katydid. This was a rare individual short-winged meadow katydid with long wings.

Next I turned to two species I have been seeking, which could overlap with the short-winged’s habitat. Straight-lanced meadow katydids in references and Internet photos lack the short-winged’s stripe pattern, instead often showing a diffuse blackish zone down that face of the femur. I went to photos of females I tentatively had identified as that species last year.

This one not only has an ovipositor much longer than the femur length, and lacks orange at the abdomen tip, but shows a femur color pattern different from the short-wingeds’ and consistent with straight-lanced reference photos. In fact it appears that the diffuse black zone is the same as the upper dark stripe on the short-winged, but differing in color and not sharply bounded. The lower stripe is there as well, but just as a trace of a line. I believe this individual may indeed have been a straight-lanced meadow katydid.

Others prove, on closer inspection, in fact to have been short-wingeds.

This young nymph has an ovipositor marginally longer than the femur, but has an instar or two to go until maturity and looks awfully orange around the abdomen. The femur color pattern clearly ties it to short-wingeds, and I think that is where this insect belongs.

The other species I need to sort out is the prairie meadow katydid. Few photos of this one are out there. In some there is no stripe pattern like the short-winged’s, in some there is a hint of one. For now I will need to focus on cerci (straighter, more pointed and with distinctly longer teeth than the short-winged male’s) and ovipositors (proportionately more curved than the short-winged female’s). I am encouraged, however, to continue looking for details of color pattern that might provide short-cuts to field identification at least in regional or local populations.

Fall Field Follow-Up

by Carl Strang

Earlier this season I reported on my search for spring field crickets in the Oak Brook area, where except for one little spot there is a curious lacuna in the distribution of that species in DuPage County. On Tuesday afternoon I followed the same route on my bike, listening for fall field crickets along the way.

I photographed this male fall field cricket last Monday at Mayslake Forest Preserve, which has no spring field crickets.

What a difference! Throughout the area that was quiet in the spring, scattered fall field crickets were singing. Later in the spring I checked some additional sites. On Saturday I went back to these, and again in every location found fall field crickets. Here is the updated county map.

Green colors indicate where I have found both spring and fall field crickets. Blue represents places with only spring field crickets, and yellow shows locations with only fall field crickets.

The three blue circles are on forest preserves, but in every case last year I found fall field crickets in residential neighborhoods or other properties just outside the preserve boundaries. Except for a few small areas such as these, fall field crickets appear to be ubiquitous in DuPage County. There remains the puzzle of the substantial area in eastern DuPage that lacks spring field crickets. Sometime this winter I will look at old aerial photos and see if they suggest anything, as landscape history is one potential influence.

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.

Female Oblong-winged Katydid

by Carl Strang

On Saturday morning I was riding my bike on the Prairie Path when I passed a katydid on the trail. I turned around, dug out the phone, and
took some photos. It proved to be an oblong-winged katydid.

The tip of the right forewing is damaged.

Not certain of the phone-camera’s capabilities, I took photos from both sides. I didn’t expect much from the backlit side, but later learned something from it.

With the sun shining through the wings, you can see not only that this is a female, but get an idea of the ovipositor’s shape.

It was palpating the trail surface, apparently picking up some minerals.

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