A Mystery Solved: Miogryllus!

by Carl Strang

In 2014 I first heard what sounded to my ear like a singing striped ground cricket, but it seemed too early in the season. It was June 21, at Hoosier Prairie Nature Preserve in Lake County, Indiana. I made a recording, then moved on to the Indiana Kankakee Sands, where I heard it again. Though these sites are a bit south of my DuPage County home, I didn’t hear striped ground crickets in DuPage until July 13. The next year I heard the same odd songs, this time at the Midewin National Tallgrass Prairie, in the middle of Will County, immediately south of DuPage. This was even earlier, on June 10. Again I made a recording. And again, I did not hear striped ground crickets in DuPage until, as it happened, July 13. In 2016 I went down to Midewin on June 28, and heard the same early, striped-ground-cricket like songs. This year, the same story, Midewin, June 23. This time, though, it seemed to me that the songs were not quite right for striped ground crickets. They seemed too precise, too even and strong. Here is a recording I made in the same location on June 28:

I went back and listened to my earlier recordings, reviewed my list of hypothetical singing insect species for the Chicago region, then checked reference recordings of their songs. The early songs did sound different from my recordings of later-season striped ground crickets, an example here:

The odd, early songs seemed to be a match for one of the hypotheticals, the eastern striped cricket, Miogryllus verticalis. Furthermore, references indicated that M. verticalis is an early season species, most abundant in June. I drove back down to Midewin on June 28. Trying to zero in on the singers was very frustrating; they seemed to have a ventriloquial quality. Eventually I flushed out and captured a female cricket near one of the singing mystery males. Looking through the clear plastic cup that held her, I could see that she was indeed an eastern striped cricket. I took a couple photos looking down into the cup. It was well that I did, because when I tried to get her positioned for a shot from the side, she gave me the slip and I was unable to recapture her.

Female eastern striped cricket, dorsal view

She was just a little smaller than a spring field cricket, which species was sharing the grassy meadow where Miogryllus were abundant. This confirms that eastern striped crickets are established in the southwestern portion of the 22-county area I define as the Chicago region. They would seem to represent yet another example of a range extension northward by a singing insect species.

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Making a Case 3: Northern Wood Cricket

by Carl Strang

Last year I concluded that I had found northern wood crickets (Gryllus vernalis) in the Winamac State Fish & Wildlife Area in Pulaski County on June 13, based on habitat and sound recordings. In 2016 I returned to that site on May 29, but did not find them singing. On June 3 I heard Gryllus crickets chirping along the Marquette Trail, near the east border of Lake County, Indiana. All were in forest or savanna areas, the singers in deeply layered black oak leaves, usually in shade under black oak trees but some in isolated collections of leaves surrounded by sand.

One of the woodland crickets’ song sites near the Marquette Trail.

One of the woodland crickets’ song sites near the Marquette Trail.

None were in the open grassy areas favored by spring field crickets (G. veletis), even though such habitat was close by. I recorded two of these individuals, and later in the season recorded field crickets in meadow and prairie habitats favored by veletis but where vernalis would not be expected, plus another individual that by habitat should be vernalis, at the Kankakee Sands site in Kankakee County, Illinois.

The results seemed contrary to what would be expected from previous studies.

The likely vernalis (forest) had lower chirp rates than likely veletis (grassland).

The likely vernalis (forest) had lower chirp rates than likely veletis (grassland).

The number of pulses per chirp was unhelpful, with likely veletis ranging 2-4, likely vernalis 3-4. Linear regressions of the two sets of data show, perhaps significantly, the same slopes of chirp rate increase with temperature (physiology of closely related species expected to show a similar response to temperature). The linear regressions indicate that, for a given temperature, forest cricket chirp rates are 1.44/second less than grassland chirp rates. All data I can find in the literature for vernalis were collected from that part of their range where they are sympatric with the southern wood cricket (G. fultoni). Jang and Gerhardt (2005. J. Evol. Biol. 19:459–472) found that fultoni song characteristics differed between populations sympatric with vernalis and those allopatric to that species. They did not study allopatric vernalis. As my recordings may be the only ones that have been made where vernalis is allopatric to fultoni, and given the clear difference between recordings in habitats for likely vernalis and likely veletis described above, so far it appears that habitat, chirp rates and temperatures will be enough to establish the presence of vernalis. The major obstacle to finalizing this conclusion is confirming the identity of the forest crickets. So far I have been unsuccessful in efforts to catch or even see one. Next year I need to continue making recordings and trying to catch and measure suspected northern wood crickets.

Recent Travels: Singing Insects

by Carl Strang

Though my main research focus is singing insects, I don’t end up photographing them much, as I am listening for them rather than looking for them. Sulfur-winged grasshoppers continued to be an early-season focus.

Though I added several more county records for the species, there was not additional range in their color variation. This female was at Cook County’s Bluff Spring Fen.

Though I added several more county records for the species, there was not additional range in their color variation. This female was at Cook County’s Bluff Spring Fen.

Here is a typical dark male, Illinois Beach State Park.

Here is a typical dark male, Illinois Beach State Park.

Not much different, this male was around the corner of Lake Michigan at Indiana Dunes National Lakeshore.

Not much different, this male was around the corner of Lake Michigan at Indiana Dunes National Lakeshore.

Only 8 species of singing insects could be found at Goose Pond. There will be many more there later in the season.

Green-striped grasshoppers still were displaying, but their days are numbered.

Green-striped grasshoppers still were displaying, but their days are numbered.

Spring field crickets seldom come into view. This female was a challenge to photograph as she crawled among the grasses.

Spring field crickets seldom come into view. This female was a challenge to photograph as she crawled among the grasses.

This katydid nymph climbed up onto the sheet illuminated by the UV light. I am reluctant to say which conehead species she might be.

This katydid nymph climbed up onto the sheet illuminated by the UV light. I am reluctant to say which conehead species she might be.

The season seems barely begun, but already I am closing the book on two species.

The Vermont Cemetery Prairie Preserve in Will County reportedly is one of the few places in the Chicago region which still harbors prairie cicadas. They were done, however, by the time I got there on June 26.

The Vermont Cemetery Prairie Preserve in Will County reportedly is one of the few places in the Chicago region which still harbors prairie cicadas. They were done, however, by the time I got there on June 26.

I have just 3 sites to check next year as good candidates for persisting prairie cicada populations. Protean shieldbacks also apparently are done. I added only 3 county records for them in their brief 2016 season. This was a wakeup call, and I will need to get on my horse right away when they start next year.

 

Field Crickets 2015

by Carl Strang

The spring field cricket and the fall field cricket are our most common members of their genus, both found in all the counties of the Chicago region. They are sibling species, identical in appearance and in song, differing only by season.

Fall field cricket

Fall field cricket

The only way to be sure that spring field crickets are done for the year, or that fall field crickets have begun, is to check the rare locations where only one of the two occurs. I have adopted the practice of counting them on my weekly bicycle rides through nearby Fermilab, where both species live in good numbers. Last year’s pattern was clear.

Two clear peaks in numbers with a well-defined valley between: spring field crickets peaked in mid-June 2014, fall field crickets in mid-September, with a separation in late July.

Two clear peaks in numbers with a well-defined valley between: spring field crickets peaked in mid-June 2014, fall field crickets in mid-September, with a separation in late July.

This year things were different in some ways, but the general pattern held.

The fall field cricket pattern in 2015 again was well defined, with an earlier peak at the beginning of September. The dividing point again was in the second half of July.

The fall field cricket pattern in 2015 again was well defined, with an earlier peak at the beginning of September. The dividing point again was in the second half of July.

The spring field cricket counts were more chaotic, and lower than those for 2014. Weather was a factor here, often rainy, often windy. This affected my ability to count them, but I think there were indeed fewer than in 2014, and also more fall field crickets than last year.

Early Season Survey: North

by Carl Strang

On Tuesday of last week I drove north to seek early season singing insects in 5 Wisconsin and northern Illinois counties. I was prepared to camp overnight, but with rain in the forecast for the next day I was happy to complete the run in one day.

My first stop was Middlefork Savanna in Lake County, Illinois.

My first stop was Middlefork Savanna in Lake County, Illinois.

Spring field crickets were singing, but vegetation still was wet from an overnight rain, and I was lucky to spot this greenstriped grasshopper to give me that county record.

Spring field crickets were singing, but vegetation still was wet from an overnight rain, and I was lucky to spot this greenstriped grasshopper to give me that county record.

From that point it was rapid-fire site hopping, and I didn’t take many photos.

An exception was this Roesel’s katydid nymph at Wadewitz Nature Camp, a Racine County (Wisconsin) Park.

An exception was this Roesel’s katydid nymph at Wadewitz Nature Camp, a Racine County (Wisconsin) Park.

Wadewitz has extensive grassy meadows, and the biggest surprise of the day was not finding displaying greenstriped grasshoppers in the warm sunny mid-day. Ultimately I was able to find both spring field crickets and greenstripeds in all 5 counties, but several stops were required in some cases.

Early Season Survey: Berrien County

by Carl Strang

I took last week as a vacation to do some early season singing insect surveying across the Chicago region. Monday took me to Berrien County, Michigan, which I had searched only once before late in the season. In addition to seeking the few species active this early, I wanted to scout some sites for their later-season potential. My first stop was Galien River County Park.

The start of the trail looked promising. The forest proved to be of good quality. I listened for northern wood crickets, but none were there.

The start of the trail looked promising. The forest proved to be of good quality. I listened for northern wood crickets, but none were there.

The park’s most spectacular feature is a wonderful canopy walkway, which ends in a platform overlooking the Galien River and moderate quality wetlands.

The park’s most spectacular feature is a wonderful canopy walkway, which ends in a platform overlooking the Galien River and moderate quality wetlands.

The walkway takes you into the upper canopy. I’m looking forward to getting back some evening later in the season.

The walkway takes you into the upper canopy. I’m looking forward to getting back some evening later in the season.

The marsh is cattail dominated, with reed canary grass invading, but has some potential for wetlands singing insects.

The marsh is cattail dominated, with reed canary grass invading, but has some potential for wetlands singing insects.

Another site new to my experience was Mud Lake Bog. Bogs are few in the region, so I had high hopes.

I was not disappointed. A boardwalk winds a good length through a high quality bog.

I was not disappointed. A boardwalk winds a good length through a high quality bog.

There was plenty of sphagnum moss, so I expect to add Berrien to the short list of counties in the region still harboring sphagnum ground crickets.

There was plenty of sphagnum moss, so I expect to add Berrien to the short list of counties in the region still harboring sphagnum ground crickets.

A final stop for the day was Warren Dunes State Park. Spring field crickets were common in the more sheltered spots of the outer dunes.

A final stop for the day was Warren Dunes State Park. Spring field crickets were common in the more sheltered spots of the outer dunes.

An early season delight is to spot the glowing yellow of hairy puccoons.

An early season delight is to spot the glowing yellow of hairy puccoons.

No need to enhance the color in a photo of these beauties.

No need to enhance the color in a photo of these beauties.

Though the day produced only 2 county species records, it was delightful for visits to familiar sites and the promise of the new ones.

 

The Cricket Double Wave

by Carl Strang

This is the time of year when the singing insect season is nearly done, with only the last song dates to note for the few rugged species still singing. I have been writing my annual research summary, and one data set recently completed was my Fermilab field cricket count. In the warm months I take bike rides through Fermilab, a U.S. Department of Energy research site, on roughly a weekly basis. I count the number of singing crickets I hear. The resulting graph has a double wave shape.

Counts of singing field crickets heard during bicycle rides following a standard route through Fermilab.

Counts of singing field crickets heard during bicycle rides following a standard route through Fermilab.

Two species are represented here, the spring field cricket and the fall field cricket. Their songs are identical to the ear. The graph shows that spring field cricket counts increased rapidly from the first appearance on May 18 to a peak in mid-June, then rapidly fell. There never was a time when fewer than 50 crickets were counted in July, probably indicating overlap between the two species, with the last spring field crickets continuing into the last half of that month. Fall field cricket numbers built rapidly to a peak in the first half of September, and exceeded the maximum count for spring field crickets in the same area, before dropping rapidly in early October.

 

First SFC’s

by Carl Strang

On Sunday afternoon, during a bike ride through Fermilab, I heard the first spring field crickets of the year. They had just begun, as there were only 3 of them. This is the third earliest date I have heard them in DuPage County, a little surprising given the late spring, though the deep snow that covered the ground most of the winter certainly provided the nymphs with protection. If a larger population survived, some statistical outliers could be starting up earlier than otherwise would be the case.

Cheating a little here: this is a fall field cricket female, but that species is physically identical to its spring sibling species.

Cheating a little here: this is a fall field cricket female, but that species is physically identical to its spring sibling species.

Apart from such uncommonly encountered critters as sulphur-winged grasshoppers and spring trigs, the next common singing insects to mature should be the predaceous katydids (Roesel’s katydid and the protean shieldback), and gladiator meadow katydids. By then I hope that the spring field crickets will have built numbers to the point where I can finish my county survey of their distribution.

Field Cricket Survey Update

by Carl Strang

The familiar chirps of field crickets can be heard through the warm months, thanks to two different species with identical songs: the spring field cricket, which begins in May and continues into July, and the fall field cricket, which begins in mid-July and continues until severe frost ends its season. I have noticed that the two species do not always occur together, and in recent years have been surveying DuPage County to map the pattern.

Fall field cricket (female). The spring field cricket looks just like this; only their seasons separate them.

Fall field cricket (female). The spring field cricket looks just like this; only their seasons separate them.

Here is the recently updated map. Green circles represent places where both species occur, blue ones mark spring field cricket-only locations, and yellow indicate where I have heard fall field crickets but not the spring species.

Here is the recently updated map. Green circles represent places where both species occur, blue ones mark spring field cricket-only locations, and yellow indicate where I have heard fall field crickets but not the spring species.

Both kinds of crickets are well distributed in the county, and with only a few exceptions, fall field crickets are ubiquitous. Some of the blue circles represent fairly large areas, though, and at some point I will want to study them more closely. Before I do that, however, I will want to spot check at least some of the places where I heard only fall field crickets. My surveys have taken place in the evenings, but recently I read a study which indicated that while fall field crickets have their peak singing time in the evening, spring field crickets are more active in the morning. It may be necessary to repeat the entire spring field cricket survey. Until then, my hypothesis is that the rigors of overwintering as nymphs place a greater limit on where spring field crickets can live. Fall field crickets, more secure in their buried egg form during the cold season, have more habitat latitude.

Scouting Jasper County

by Carl Strang

The Jasper-Pulaski State Fish and Wildlife Area in Indiana started out as a recreational destination for hunters and fishermen. Natural history enthusiasts in the region associate J-P with sandhill cranes, as the big birds pause there by the thousands when they migrate north and south, and birders congregate as well, to see them.

J-P seemed a good place to find singing insects in Jasper County, and I stopped there to scout the property on my way home from last weekend’s trip. Some of the back roads lead to extensive ponds and marshes, which will be of interest later in the season. My favorite spot, though, was at an intersection of two gravel roads where the soil was heavy in sand, with a black oak savanna and wide berms of sand prairie vegetation.

Tiny oaks form a vanguard as the savanna reaches into the prairie.

Tiny oaks form a vanguard as the savanna reaches into the prairie.

As I walked one of the roads, I flushed a sulfur-winged grasshopper. I had been hoping for a photo opportunity with this species.

At first glance this insect seems doomed, its dark color contrasting with the pale sand.

At first glance this insect seems doomed, its dark color contrasting with the pale sand.

Unless you are very close to it, however, the grasshopper just looks like a little stick or piece of debris.

The folded forewings conceal bright yellow hind wings with broad black edges.

The folded forewings conceal bright yellow hind wings with broad black edges.

The next time a similar opportunity comes up, I’ll try for a flight photo that will show those hind wings. In any case, I drove away from J-P with some great locations, and three early-season species to start my Jasper County singing insects list (green-striped grasshopper and spring field cricket were the other two).

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