Closing the Book on Green-winged Cicadas

by Carl Strang

The green-winged cicada (Diceroprocta vitripennis) provides a favorite example of why I need to include 22 counties in my survey of Chicago-region singing insects. I checked a final two locations recently, and am satisfied that I have a good sense of where this species occurs.

Black dots indicate counties where green-winged cicadas can be found.

The most important habitat feature appears to be sandy soil. Cicadas spend most of their lives underground, so it is not surprising that soil texture can influence their distribution. The mapped area contains two sandy regions: the dunes edge of Lake Michigan in Indiana and Michigan, and the Kankakee River corridor. The cicadas do not, however, extend throughout those soil areas. They thin out quickly in western Starke and Pulaski Counties, Indiana, and do not reach into the sand soil portions of St. Joseph and Marshall Counties.

Green-winged cicadas had an important lesson for me this year. Previously I had thought of them as a woodland species, having observed them singing in trees, especially in black oak savannas and woodlands. Then I came to this spot in Newton County, Indiana:

A single large cottonwood and two smaller trees towered above clusters of shrubs.

I was surprised to step out of the car, expecting to focus on sand-soil grasshoppers, and hear green-winged cicadas singing. As I approached them I found that they were singing, not from the big trees, but from plants no taller than me, winged sumacs and a small black oak.

This discovery provided a welcome opportunity to photograph live green-winged cicadas.

They were very alert, and required a glacially slow stalk.

Feel free to wave back. No one is watching.

I also found a site in Jasper County where the cicadas were singing from shrubs. They can be fairly loud at close range, but they are small, with bodies not much more than an inch long, so the song quickly attenuates over distance. It seems to carry better when the singing perch is in a tree. The song is a distinctive pulsing rasp:

These early season cicadas sing mornings to mid-afternoons, and largely are done by the end of July.

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Southern Lessons

by Carl Strang

This year’s chapter in the series of annual bioblitzes organized by the Indiana Academy of Sciences took place at Eagle Creek Park in northern Indianapolis on June 2-3. This is early enough in the season that there were few singing insects for me to find, but I was able to gain valuable experience with two southern species that occur or have occurred in the Chicago region.

The first of these is the spring trig.

Female spring trig at Eagle Creek.

This species of tiny cricket first was described in 2014. That is surprising, given its abundance in southern Indiana and its extensive range beyond the state. It proved to be common in a range of habitats at Eagle Creek Park, from woodland edges to grassy meadows.

Spring trigs appear plain-faced to the eye, but bright light and magnification reveal a pattern of fine dark lines.

I learned more about the spring trig’s habitat, and found that I can hear them easily while driving at speeds of 30mph or less. This allowed me to get clarity on the species in the Chicago region. Driving in the southernmost counties, I found widely scattered small colonies in Fulton and Jasper counties, at road edges where wider bands of herbaceous plants were backed by woodlands. In the future I expect to find them in southern Pulaski and Newton counties, too, but not north of there.

Eagle Creek Park also has a large population of northern wood crickets.

The northern wood cricket is a forest species that is smaller and blacker than the spring field cricket, which could be heard chirping in the park’s meadow areas.

The spring field cricket is a few millimeters longer, typically has bronzy wings, and has a proportionately broader head and thorax.

Recordings I made during the bioblitz, and at home with a captive male, have provided further clarity on northern wood cricket song characteristics. Their chirps may never have 4 pulses (commonly 2 or 3), and almost never rise above 5 kHz in pitch, where spring field crickets often have 4-pulse chirps, and seldom drop below 5 kHz. Habitat also helps separate the two. I dug deeper into the literature, and learned more about historical records of the species in two Chicago region counties. Those observations were made in 1902, and I went to the sites in the weeks after the bioblitz. Northern wood crickets no longer occur there. I believe the records are correct, but that the crickets have gone extinct in those places. Northern wood crickets are reported to be sensitive to forest fragmentation, perhaps especially so in the northern fringe of their range, and such fragmentation clearly took place where they once were found in Lake and Marshall counties. I will continue to check the region’s larger surviving forest blocks, but it seems likely that the species no longer occurs in northern Indiana.

Incidentally, the other expected early-season singing insect, the green-striped grasshopper, lives in Eagle Creek Park’s meadows and prairie areas.

Next year’s bioblitz is expected to take place in one of my counties, and I am looking forward to the experience.

 

Wood Be? Wouldn’t Be!

by Carl Strang

For a couple years now, I have been pursuing early-season crickets that I thought must be northern wood crickets (Gryllus vernalis). These close relatives of our familiar spring field crickets (Gryllus pennsylvanicus) had been reported to occur in two of the counties in the Chicago region, both in northern Indiana. Spring field crickets are abundant in well-drained open grassy areas in my home county of DuPage, in Illinois. When I started hearing chirping Gryllus songs in Indiana woodlands and savannas, coming from accumulations of oak leaves often under trees, I figured these must be wood crickets.

For example, my attention was drawn to clumps of oak leaves surrounded by sand, along the Marquette Trail in the Indiana Dunes National Lakeshore. Nothing grassy about this!

A few days ago, I headed to the Marquette Trail to make another attempt to see one of these crickets. I wanted to confirm my suspicion, but also to get photos of a living northern wood cricket.

All I had were photos of museum specimens like this. Note the taper from the back of the thorax through the head. Spring field crickets are broader in front.

As I walked along a section of trail beside a road, I heard one of the crickets singing in a narrow band of accumulated oak leaves at the base of a hill.

An earlier controlled burn had removed nearly all the available cover. Puccoons bloomed magnificently above the line of leaves.

I made a sound recording of the singing cricket, and used the shotgun microphone to get his exact location. Then I lifted the layers of leaves to see if I could spot him.

You may be able to see the tunnels in the sand. At first I figured he made a quick retreat into them when I lifted the leaves.

If you look in the lower right-hand corner of the photo, however, you may see a small oval of reflected light. After taking the picture I discovered it was the cricket! I got him into a plastic cup.

I got my photos, and did my best to make him a northern wood cricket, but in fact he was a spring field cricket. Not only were his proportions wrong, but he held still and let me hold calipers just above him for a measurement. Spring field crickets usually are 16mm long, northern wood crickets 14mm, and this one was 16.8mm.

After reviewing my recordings, I think all the woodland Gryllus crickets I have heard in the region in fact are spring field crickets. There were small technical differences in song parameters between crickets in tree leaves and those in grassy areas, but I have to conclude that they don’t represent a species difference. The lesson ultimately is one of habitat. Spring field crickets on clay soils occur only in well-drained grasses. In sandy areas they broaden their habitat into woodland edges, and don’t associate strictly with grasses.

Further review of reference recordings points me toward northern wood crickets having more rapid chirping speed, and a lower pitch, resulting in a slightly less musical impression. So it’s back to square one for northern wood crickets in the region, and my insistence on visual confirmation of suspected but ambiguous species observations is vindicated.

Singing Insects Guide 2018

by Carl Strang

The general summary of my singing insects research is a 116-page guide, Singing Insects of the Chicago Region. It contains photos, maps, links to song recordings, and information with a page for each species. It is available for free as a 5-6mb PDF document, sent as an e-mail attachment.

This Texas bush katydid continues as the cover photo.

If you are on the mailing list, you should have received the updated version earlier this month. To get a copy and get on the list for annual updates, send me a request at wildlifer@aol.com

This year’s version is expanded significantly, as I created pages for species which occurred historically in the region but which I have not yet found. I also added photos of museum specimens in cases where I have no photos of live insects, and have a new page for the eastern striped cricket, which I found for the first time in 2017. Already I know that I will need to add a page in next year’s version, as Nancy Collins has sent me documentation of a 2005 find of tamarack tree crickets in Berrien County.

The long-term plan is to continue this annual updating through 2024, when periodical cicadas have their next major emergence in the region. Then I will see about getting a print version made. In the meantime, if you have need for a higher-resolution photo than the compressed (but adequate, I think) versions in the guide, send a request to that same e-mail address.

One Last Look Back

by Carl Strang

My recent blog posts have shared highlights of this year’s field season, as I searched for singing insects in the 22-county area I define as the Chicago region. Those accounts haven’t told the whole story, though, and I have a few last photos to shake out of the bag. These fill out some of the experience of doing this kind of regional study.

For instance, other animals have enhanced the delight.

The chalk-fronted corporal is a dragonfly I have encountered only in the northern portion of the region, in this case at the Lulu Lake Nature Preserve in northern Walworth County, Wisconsin.

Walsh’s grasshopper was a new one for me. Not a singing species, but an interesting find at the Poverty Prairie in DuPage County’s Waterfall Glen Forest Preserve.

Turkey vultures assemble at dusk on the Culver, Indiana, water tower. My travels take me back to my home town a few times each season.

Interesting and beautiful scenes are to be found in the relatively undisturbed wild areas which are my main destinations.

An early evening rainbow at Conrad Station in the Indiana Kankakee Sands presaged a thunderstorm-dodging drive home on July 2.

Pinholes between tree leaves cast solar eclipse shadows at Blackwell Forest Preserve. Though the moon covered around 90% of the sun at peak, I detected no change in singing insect activity.

One of the more beautiful scenes was this panne in the Indiana dunes.

I had hoped to find delicate meadow katydids in the pannes. Dusky-faced meadow katydids were a good find there, but that species has a solid hold in other dunes wetlands.

The Pembroke Savanna in the Illinois Kankakee Sands is one of my favorite sites.

I believe these white pines at Warren Dunes State Park in Berrien County, Michigan, are the same ones where Richard Alexander found treetop bush katydids in 1971. He described the trees as small, but all are tall now. They still foster pine tree crickets, but I did not find any bush katydids.

I ended up with 115 county records for the season, totaling all newly found singing insect species over all the counties.

So far, I have found sprinkled grasshoppers only in oak savannas on sand soils.

Dusky-faced meadow katydids at the Indiana Kankakee Sands were a Newton County record.

This curve-tailed bush katydid at the Jasper-Pulaski Fish and Wildlife Area in Indiana provided a Jasper County record for my study.

I found a healthy population of long-tailed meadow katydids, including this brown-legged male, at Ferson Creek Fen in Kane County.

The Ferson Creek population also had green-legged variants, including this female.

Lisa Rainsong, Wendy Partridge and I drove south to Loda Prairie to check out the bush cicadas there. I concluded this year that the species does not occur in the Chicago region.

This Texas bush katydid was singing in early October at Springbrook Prairie Forest Preserve, DuPage County. I had an observation of this species on October 17, my latest ever in the region.

Most of the long winter remains, and as I compile data, write reports, and visit museums, I will be looking forward to another collection of rich experiences as I resume my field study in 2018.

 

Seeking Seasides

by Carl Strang

Coming into 2017, I had found seaside grasshoppers (Trimerotropis maritima) in most of the counties bordering Lake Michigan in the Chicago region. This band-winged grasshopper is mainly a beach-dwelling species, though it also occurs at Burnham Prairie, an inland site in Cook County

Seaside grasshopper, Indiana Dunes. This individual belongs to a population living on fine grained quartz sand.

The hind wings are bright yellow, and males can rattle their wings loudly in flight

Seaside grasshopper, Illinois Beach State Park. This one lives on a substrate of mixed fine stones ground by glaciers and waves. Selective pressures clearly have been at work on these hoppers.

Prior to this year I had found the species in Berrien, Porter, Lake (Indiana), Cook, and Lake (Illinois) Counties. In 2017 I added LaPorte County, and went up to Cliffside Park in Racine County, where GoogleEarth showed a narrow line of dunes and beach. I found, though, that storms and a risen lake level had removed these

The edge of Lake Michigan at Cliffside Park, looking north. Waves now wash right up to the cliff base.

Looking south from the same position.

I thought that might mean the end of the search, but a new GoogleEarth survey showed parks in the cities of Racine and Kenosha that looked promising. Both proved to have seaside grasshoppers, so now with the addition of Racine and Kenosha Counties I regard the Chicago region map complete for the species. I remain open, however, to stumbling across seaside grasshoppers at additional inland sites.

More Prairie Meadow Katydids

 

by Carl Strang

Last year I first encountered what I thought were prairie meadow katydids (Conocephalus saltans), in my survey of the Chicago region’s singing insects. Further study confirmed my identifications, and set the stage for finding the species in a third location in 2017. On September 2, Lisa Rainsong and I ran into a cluster of small meadow katydids at the Pembroke Savanna Nature Preserve, a Nature Conservancy savanna in eastern Kankakee County. These proved to be a mix of two species, straight-lanced meadow katydids (Conocephalus strictus) and prairie meadow katydids.

A scene at Pembroke Savanna, which I regard as the most beautiful site in the 22-county Chicago region.

Finding these two similar species together provided us with a tutorial in distinguishing them. Most of the individuals were females, and the contrast in their ovipositors could not be starker. Those of the prairie meadow katydids had a slight curve, and were much shorter.

Female prairie meadow katydid, Pembroke

Straight-lanced females have straight ovipositors that typically are as long as their bodies, or longer.

Female straight-lanced meadow katydid, Judy Burton Nature Preserve, Indiana. This one is atypical in having long wings. Most have wings about a third the length of the abdomen.

Prairie meadow katydids have wings that usually are only a quarter of the abdomen length. The knob at the tip of the head is more pronounced, though both species have this knob. The sides of the hind femurs also are different. In prairie meadow katydids there is a pattern of thin lines that resemble a ladder, on a brown leg. There usually is a diffuse black line that appears to be within the straight-lanced meadow katydid’s green hind femur. Some variation occurs in many of these features, so I advise caution and the examination of several individuals within a population.

Males have been fewer in both species, in the populations I have examined.

 

Male prairie meadow katydid, Pembroke

Again, the more exaggerated head knob, shorter wings, and different femur pattern are helpful. Cerci are very different in the two species, also.

Male straight-lanced meadow katydid, from another eastern Kankakee County savanna site.

I did not get a photo showing the prairie meadow katydid’s cerci, but their ends are much shorter, proportionately, than those of the straight-lanced in the photo, comparable in length to the teeth, and bend outward somewhat rather than being straight.

A final curious note from Pembroke was that the prairie meadow katydids were all brown, as the photos show. The straight-lanced meadow katydids had considerable amounts of green color. This may have been the result of local selective pressures, as this is not a consistent difference across the species’ ranges.

Rounding Out Conehead Maps

by Carl Strang

This has been a good year in my quest for coneheads. The coneheaded katydids of genus Neoconocephalus are represented by six species (historically, seven) in the 22 counties I define as the Chicago region.

 

Sword-bearing conehead. This katydid is named for the female’s long ovipositor.

Prior to 2017, I had found sword-bearing coneheads (N. ensiger) in every county. In a recent post, I detailed the completion of the search for Nebraska coneheads (N. nebrascensis), which can be found in all but the three Wisconsin counties of the region. In another post I described progress in finding slightly musical coneheads (N. exiliscanorus).

 

Robust conehead in singing posture

 

Today I can report that I now have found two more species in all 22 counties: the robust conehead (N. robustus), and the round-tipped conehead (N. retusus). Though it extends into Wisconsin, the round-tipped thins out rapidly south to north, and some effort was needed to find a singing round-tipped conehead in the southern portion of Racine County, the region’s northernmost county.

 

Round-tipped conehead. The shape of the cone and the amount of black pigmentation help in species identification. The large jaws help them with their diet of seeds, and teach researchers to use caution in handling them.

The sixth species is the marsh conehead (N. palustris), which so far I have found only in Porter County, Indiana. Though I continue seeking the slender conehead (N. lyristes), I fear that it is extinct in the region.

 

Slender conehead. This museum specimen from the early 20th Century was collected in what is now Illinois Beach State Park. I have failed to find the species in my thorough exploration of its habitats there.

Wetland Singing Insects Update

by Carl Strang

For years, now, my biggest conservation concern among the singing insects has been in the wetlands. Though our historically abundant prairies in the Chicago region were diminished nearly to nothing by 19th– and 20th-century agriculture, preservation and restoration projects across the region have halted and, to a small degree, reversed that trend. The same could be said for savannas, and our forests did not suffer as much.

Wetlands, like prairies, declined thanks to agriculture, but a new challenge continues to threaten their integrity: invasive wetland plants. Four of these are especially problematic: common reed (Phragmites australis), reed canary grass (Phalaris arundinacea), hybrid cattails (Typha x glauca), and purple loosestrife (Lythrum salicaria). These plants, released from consumers and competitors, have displaced the diverse native species in a large and increasing portion of our wetland acreage. The loss of native wetland grasses, especially, appears to account for the difficulty I am experiencing in finding wetland katydids.

Reed canary grass

Two species that were here historically, I have not found at all: the delicate meadow katydid (Orchelimum delicatum), and the slender conehead (Neoconocephalus lyristes). In the past these were known to occur in four and three, respectively, of the Chicago region’s 22 counties, and I am nearly out of places to check where they might still live. The stripe-faced meadow katydid (O. concinnum), once found in 8 of the counties, appears to be down to a single population at Illinois Beach State Park.

Stripe-faced meadow katydid

Two wetland katydids are doing well. Gladiator meadow katydids (O. gladiator) and black-legged meadow katydids (O. nigripes) are tolerant of the invasive plants, and remain common in every county.

That leaves an in-between category of wetland singing insects that apparently are limited to invasives-free wetlands, and are managing to hang on in a few to several sites. Northern mole crickets (Neocurtilla hexadactyla) occur in wet prairies as well as marshes. In 2017 I added records for two more sites, one of which represented an additional county record. To date I have found them in 10 counties, and remain optimistic that I can add more populations to the inventory.

Dusky-faced meadow katydids (O. campestre) historically were ubiquitous in our marshes. To date I have found them only in marshes with minimal impact by the invasive plants. These katydids seem able to persist in relatively small wetland areas, however, and each year I have been able to add new populations to my list. In 2017 I found them in the Indiana Kankakee Sands preserve, adding Newton County to the record, and in the Tefft Savanna preserve in Jasper County, also a county record. That brings to seven the number of counties where I have found the species, but there are seven more where it once lived, but where my search has been unsuccessful. Dusky-faced meadow katydids also proved this year to be abundant in the panne wetlands at West Beach in the Indiana Dunes National Lakeshore. That was a good find, but I had hoped for delicate meadow katydids there.

Female dusky-faced meadow katydid, Tefft Savanna

Finally, this year I added a third population and county for the nimble meadow katydid (O. volantum). They were singing from arrowheads (Sagittaria sp.) mixed with cattails along Grant Creek in the Midewin National Tallgrass Prairie. That find was made from a kayak, and that is the vehicle from which further searching for the species will need to happen, as this species likes plants growing in relatively deep water. Some places which historically held nimble meadow katydids no longer have them, but several other sites remain for me to check in future years.

Jumping North

by Carl Strang

Of the many species of singing insects that have expanded their ranges northward in the past half century, the jumping bush cricket (Orocharis saltator) has been the fastest mover in the Chicago region. I have done my best to keep up with them ever since 2007, when I first heard their bell-like chirps in DuPage County, Illinois. As their density built dramatically in southern DuPage, the front of their advance typically shifted half a mile north each year.

Jumping bush cricket

At the same time, they were on the move to the east in Cook County. I first found them in Kane County, to the west, in 2014. The line of their advancing front has angled southwest to northeast, suggesting an Indiana source of the invasion, though last year I heard them singing just north of Peoria, well southwest of the Chicago region.

Over the past couple of years, what seemed to be a simple spread has become complicated. First, the advance apparently stalled out in the northeast corner of Cook County, just south of the Lake County border. Farther west, however, the crickets’ expansion has, if anything, accelerated. Following the Fox River, they have moved 8 miles up its east bank in 3 years.

But that’s not all. This year I found them even farther north on the west bank. Then, on September 20, I heard jumping bush crickets singing at the edge of Wauconda, in western Lake County. Subsequent checking revealed that this is an isolated small group, probably a human-assisted introduction. I will be interested in seeing if they successfully reproduce there. In any case, there is no end in sight to the dramatic northward movement of this species, and I will continue to invest some time each year in documenting it.

Map of the Chicago region, showing locations for jumping bush crickets. Black dots indicate counties where the species has become established. Stars indicate farthest north locations: red for 2014, yellow for 2015, green for 2016, and the two blue stars indicate new north locations in 2017, along the west bank of the Fox River in Kane County, and at Wauconda in Lake County.

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