by Carl Strang

After last year’s field season was done, I learned of the possibility that slow-tinkling trigs (Anaxipha tinnulenta) might be in my study region. Checking this needed to be a high priority this year, because the tink-tink-tink song of this newly described little cricket is very similar to that of the tinkling ground cricket (Allonemobius tinnulus). In fact, I had assumed that all the tinkling songs I had been hearing across the region were from the ground cricket. I sent two of my recordings from past years to Wil Hershberger, the experienced sound recordist, and he gave reason to think that these both were of slow-tinkling trigs rather than tinkling ground crickets, as I had assumed.

I began this year’s quest at Big Marsh, a Chicago Park District site where I heard tinkling songs last year. I began finding the songs, coming from dense, tall vegetation. I saw some trigs in that first spot, and did not see tinkling ground crickets, but that was not decisive because I also could hear the songs of another species, Say’s trig (Anaxipha exigua), in the same spot. The 2014 paper by Tom Walker and David Funk which described the slow-tinkling trig indicated that its general appearance is practically identical to that of Say’s trig.

In a second, more open location, there were tinkling songs but no Say’s trigs were singing. I spent a lot of time on the ground trying to spot one of the singers. Clearly they were 2-3 feet above the ground, which practically ruled out tinkling ground crickets, but I needed more. Though I never saw a singing tinkler, I caught a female trig in the same clump of plants. I photographed her before returning her, and she met the one gross anatomical separator from Say’s trig, having a proportionately longer ovipositor:

My next attempt came a few days later. I traveled to Indiana’s Jasper-Pulaski Fish & Wildlife Area. When I checked in at the site’s headquarters, I heard tinkling songs coming from some tall, dense herbaceous vegetation nearby. I made a recording but did not see any suspects:

 I went on to some woodland edges where I have photographed tinkling ground crickets in the past. Immediately it was clear that the tinkling songs there were different from the ones at the headquarters:

They were quieter, though that could have been because the singers were buried in leaf litter. More significantly, they were faster, the tinkling notes coming at a rate of 8 notes per second rather than 6. That may not seem like much, but I noticed it immediately. If anything, the temperature there was a little cooler, so if all else was equal the rate should have been slower rather than faster. There was no question that these were tinkling ground crickets, which I could see near the recorded individuals.

I went to another more open spot with tall dense vegetation where members of the slower tinkling species were singing. I made a recording, then dug in with my net. I caught two female trigs and a male, which I placed in a container to take home. No Say’s trigs were singing there, so I was hopeful. I set the crickets up in a cage, and to my delight that evening the male began to produce his tinkling song. That was the final confirmation I needed.

So far, my analysis of the sound recordings indicates that tinkling ground crickets have a faster note rate than slow-tinkling trigs at similar temperatures. The pitches (carrier frequencies) of the songs are so similar that these cannot be used to separate the species. There is another difference, however, that Wil pointed out and I can confirm. When the notes are magnified in a sonograph, those of the two species usually have different shapes. First, the slow-tinkling trig:

The largest, brightest notes are those of the trig. The shape is generally horizontal, in this case with symmetrical downward tails at each end. Sometimes the shape is a gentle, nearly flat arc with no tails. Sometimes, however, there is a lower descending tail on the right end. Now, the tinkling ground cricket:

Here there is practically no horizontal portion, the shape angling down and to the right. Sometimes the shape is sharply arched, but the right end almost always shows a longer downward tail. If you look again at the trig’s sonograph, you can see a line of smaller, more rapid notes just above those of the trig. There was an Allard’s ground cricket (Allonemobius allardi), a close relative of the tinkling ground cricket, close enough to be picked up by the microphone. Allard’s has an even more rapid note production than the tinkling ground cricket, but you can see that it shares the note shape of a downward right-hand tail.

Since those initial experiences, I have made a few dozen recordings of tinkling songs in several counties. Often note shape alone is distinctive enough to ensure an identification, but some are ambiguous enough to give me pause. I found that I need to standardize the notes, expanding them so they are 0.2 inches long on the computer screen. All of the songs coming from leaf litter on the ground have been those of tinkling ground crickets, and all of those a foot or more above the ground have been those of slow-tinkling trigs. Tall dense vegetation always has proven to house the trigs. Finally, trig songs are produced at a rate slower than ground cricket songs. All but one of the 18 ground cricket songs had note rates of 8 per second or higher. All but one of the trig songs were at 7.5 per second or lower, and 40 of the 46 were below 7. These all were recordings made at relatively warm temperatures, and higher temperatures were associated with higher song rates. At a few sites where both species were present, the difference was clear.

So in the upcoming annual revision of my guide to the singing insects of the Chicago region I will be adding a page for the slow-tinkling trig, and the site maps of these two species will show only locations for each that I have been able to verify visually or through sound recording analysis. The trigs have proven to be more widespread, and I suspect that in DuPage County, at least, they are increasing.

Striped Faces

by Carl Strang

In early August I went down to Will County to check some new sites for singing grasshoppers. Along the way I stopped at a spot in the Des Plaines Conservation Area where I had found unusual grasshoppers in the past. As before, there were Kiowa rangeland grasshoppers (Trachyrhachys kiowa) in the dolomite prairie area.

This western member of the band-winged grasshopper subfamily is uncommon in the Chicago region.

As I was walking back to the car I turned on my SongFinder, a device which lowers high-pitched sounds, like the songs of many singing insects, so that older ears like mine can hear them. I heard some meadow katydid songs, coming from wet areas, that I decided to check out. To my great surprise I saw a striped face looking up at me from the grass.

I caught it carefully, wanting to document only the second population of stripe-faced meadow katydids (Orchelimum concinnum) I have found in the region.

In addition to the female, which I released after taking the photos, I saw a few others. At some point I need to assess the size of this population. There have been indications that this species is associated with relatively high-pH wetlands, which certainly should be the case in that spot with all the dolomite bedrock so close to the surface.

White Whiskers

by Carl Strang

A very busy field season continues, so I have fallen behind in these posts. Today’s story goes back to the last half of July. I had learned through iNaturalist that one of the singing grasshopper species, historically in my region but which I never had discovered, had been photographed in the south unit of Illinois Beach State Park. I went there on July 21. Soon I began finding them.

White-whiskered grasshoppers (Ageneotettix deorum) are small and beautifully patterned to match their habitat.

They are named for the white antennae. The wings just reach the end of the abdomen, so they are not strong fliers. They mainly jump, sometimes with a bit of wing assist, but then want to sit quietly and count on their camo.

Their habitat reportedly includes bare sand, and that certainly was true were I found them. While I was there I assessed the associated grasshopper community. Another singing grasshopper from different subfamily was the mottled sand grasshopper (Spharagemon collare):

Their brightly colored yellow hind wings stood out when they flew. A smaller relative of theirs, the longhorn band-winged grasshopper (Psinidia fenestralis), also was present in good numbers:

Though these typically have bright red hind wings, at Illinois Beach State Park those wings often are nearly transparent.

Most of the grasshoppers were non-singing species. Among those was Hesperotettix viridis, the meadow purple-striped grasshopper:

A few days later I went down to the Indiana Dunes National Lakeshore, hoping to take advantage of my new knowledge to find white-whiskered grasshoppers there. I couldn’t find any, and in fact all the grasshoppers I saw were strong fliers. Though the habitat looked very similar, one difference was noticeable, the presence of a common predator.

Six-lined racerunners are lizards which like to munch on grasshoppers. Even the good fliers were relatively few compared to Illinois Beach State Park, possibly their nymphs having been culled by the lizards. I have a few more places to check for white-whiskered grasshoppers in future years, but had to move on to other things in 2021.

PC P.S. (Periodical Cicada Postscript)

by Carl Strang

I thought I had finished with periodical cicadas, as indicated a couple blog posts ago. For completeness’ sake, though, I continued checking for late reports in my region. There were two that needed follow-up. The first was in Plymouth, Marshall County of Indiana. I found that report just before heading to the Mosquito Creek Bioblitz, and so altered my course to swing by there on the way down. The forest was large enough that it may have supported a large emergence in the past, but there was only one cicada singing in the reported neighborhood, and two others on the opposite edge of the forest.

That detour allowed me to make a final check of the Fulton County emergence. Cicadas still were singing, and had spread across the roads to the south and west, but clearly were past their peak. I picked up some dead ones from the roadside to serve as voucher specimens.

A second late report on iNaturalist was accompanied by the intriguing comment, “Tons of them flying around.” The location was in LaPorte County at Kingsbury Fish & Wildlife Area. That had been one of my stops in my earlier tour, when I had heard only a few individuals singing, but the report pointed to a different forest farther east which I had not checked. It was worth a day trip, and I headed over there on Friday.

As I drove to the forested east end of Nickel Road, I began to see lots of leafy twigs on the road. The trees gave the impression of autumn rather than early summer.

There was as much brown as green in the foliage

These were flags, the killed ends of branches resulting from the massive injection of periodical cicada eggs.

Oaks were the most heavily impacted trees.

I explored on foot. Most of the twigs on the ground did not have oviposition scars, an exception being a black cherry twig:

Cherry twig with periodical cicada oviposition scars

On the other hand, all the browned twigs still attached to trees were on branches with abundant egg scars:

Oak twig with periodical cicada oviposition scars

The singing was done. There were plenty of bits of dead cicadas on the ground:

Cicada remains

Scavengers had cleaned up the bodies for the most part, and it took a while for me to find a few relatively intact voucher specimens in the fringe of the affected area. As I drove back west the numbers of flags diminished, until by the time I reached the area I had checked on my previous visit there were practically none. I conclude that this was a second major Brood X emergence in the northwestern ten Indiana counties.

Mosquito Creek Bioblitz

by Carl Strang

For many years, the Indiana Academy of Science has organized an annual bioblitz. This is a gathering of scientists, both professional and amateur, who spend a weekend compiling a list of all the species in their respective areas of expertise that they can find in a designated location. I first participated in the 2012 Kankakee Sands event, and it has been a highlight of each field season since. Last year’s bioblitz had to be postponed thanks to the pandemic, but we were able to resume the series this June in the Mosquito Creek area of Harrison County, bounded by a bend of the Ohio River.

Most of the bioblitzes have been early in the season, before most singing insects have matured, but the southern ones especially have provided experiences which have made them worthwhile for my research. One example is my first encountering the spring trig (Anaxipha vernalis) at the Connor Prairie bioblitz in 2013. The species then had not been formally described, and simply was listed in the Singing Insects of North America website (SINA) as “Anaxipha species G.” I later found a few in the southern edge of my study region, but most of my experiences with them have been through the bioblitzes.

This year they proved to be by far the most abundant singing insect at Mosquito Creek, and I was able to resolve a question that had bothered me. Spring trigs generally remain buried in dense grasses close to the ground, and are difficult to see. I had collected a male at Connor Prairie, and he had a head that was all dark brown. In a later bioblitz at Eagle Creek Park I had photographed a female, and her head was pale with a scrollwork pattern of dark lines:

This year I wanted to confirm this sexual difference, and was able to get a male and a female in the same jar. The head color difference was as I had noted before, the male’s uniformly dark:

Furthermore, the male’s abdomen was black or very dark brown, the female’s a much paler tan.

My first couple of hours of bioblitz work were spent in a grassy parking area at one of the Mosquito Creek sites.

I was struck by rapid sharp chirping around the grassy edge near the forest, the chirps contrasting with the spring trig continuo:

The chirps had the quality of field crickets, but were so compressed that the pulses could not be distinguished by ear. That combination of location and chirp quality pointed to southern wood cricket (Gryllus fultoni), a species I never had met. I flushed one out, and the combination of yellow cerci and brown wings on a generally black field cricket confirmed the identification:

Though southern wood crickets prefer to be in the forest, they have been shown to shift to the forest edge when their close relative, the northern wood cricket (G. vernalis), is present. This proved to be the case in the evening, when northern wood crickets started singing within the forest with their lower volume, less compressed chirps. This apparently is now only the second county where the southern wood cricket has been documented in Indiana.

A third species in that parking lot was the eastern striped cricket, Miogryllus saussurei (Tom Walker has recently added an interesting historical account of this species’ naming to SINA, and the next edition of my guide will replace the verticalis species name accordingly). I made a recording there of the distinctive buzzing chirps:

I needed to photograph a male, and succeeded in flushing one out:

I had hoped to find some exotic (to my experience) early season grasshoppers, but the only ones I found are common in the northern part of the state as well, the green-striped grasshopper (Chortophaga viridifasciata) and the sulfur-winged grasshopper (Arphia sulphurea). The latter were very dark brown with tan wing edges, and their hind wings were bright orange-yellow:

I found three more species. Two of these, a spring field cricket (Gryllus veletis) and a group of protean shieldbacks (Atlanticus testaceus) are common and familiar in the North, but a loud sharp trilling on the grounds of The Nature Conservancy’s headquarters grabbed my attention:

It was louder, had a more rapid pulse rate and slightly different pitch from the nearby spring trigs. I immediately thought of the southeastern field cricket (Gryllus rubens), which I had heard on visits to my brother’s residence in North Carolina. I had listed it as a possibility because the species had been documented once before in Indiana, a few counties west of Mosquito Creek. I was able to flush out the singer, and confirmed that it was a field cricket:

The southeastern field cricket is unusual for its genus in having long trilling songs rather than discrete chirps.

So there it is. The plant people list hundreds of species in these bioblitzes, birders find dozens, and I perennially have one of the lowest species counts. The experience always proves worthwhile, both for the experiences like the ones described here and enjoying the company of other field biologists.

Cicada Search Concluded

by Carl Strang

A week after my first visit I returned to the forest in Fulton County, Indiana, that had begun to show a significant emergence of periodical cicadas described in the previous post. I found them well into the peak of their appearance. There were more newly emerged cicadas than before, and fresh cicadas and emptied nymphal skins were visible all along the trail in the forest interior.

This time, skins outnumbered new cicadas. The only species present remained Linnaeus’s 17-year cicada, Magicicada septendecim.

The chorus was very loud, and as I drove the nearby roads to determine the extent of this emergence, I found that I could hear it clearly from a quarter mile away and it was audible from half a mile. It extended a mile north of the road where I first encountered the cicadas, and was as much as half a mile wide, but there are clearings within that block so that the forest with cicadas covers an estimated 243 acres or 98 hectares, which my earlier research suggests should be plenty large enough to sustain this population.

Between the two visits, and after the second one, I checked the remaining large forest areas in the 10 counties of northwest Indiana. I found nothing comparable to the Fulton County emergence. There were a few scattered (countable) septendecim in a portion of Potato Creek State Park in St. Joseph County, and the same in a small area of the Kingsbury Fish & Wildlife Area in LaPorte County. Beyond those there were only a few singles, two septendecim in LaPorte County, two Cassin’s 17-year cicadas (M. cassinii) in Porter County, and one cassinii in Lake County.

Considering these observations and historical records, I suspect that the Kankakee River and its broad sandy soil region represents a dividing line between Broods X and XIII in Indiana, at least in the western part. Brood XIII then would extend eastward along the elevated Valparaiso Moraine between the Kankakee River and Lake Michigan. If so, that would place the Fulton and St. Joseph County cicadas in Brood X. The singles in Lake and Porter Counties would be stragglers of Brood XIII. The LaPorte County septendecim may represent vanishing traces of Brood X that once spilled onto the Valparaiso Moraine from the east.

Septendecim Surprise

by Carl Strang

A year ago I was busy in June documenting a 4-year-early emergence of periodical cicadas in a part of northeast Illinois. Periodical cicadas come out in large numbers somewhere in eastern North America each year, and the different areas and years are called “broods,” designated by Roman numerals. The northeast Illinois ones are in Brood XIII and their next main emergence will be in 2024.

This is the year for Brood X, which occupies a large portion of the eastern U.S. According to Gene Kritsky, who has thoroughly researched the history of these insects, Brood X periodical cicadas at one time emerged in every Indiana county. Now they are known mainly in the southern half of that state, but it seemed appropriate for me to check the 10 northwest Indiana counties of my singing insects study region for possible survivors. I didn’t expect to find any, as none have been reported there in recent years.

My own research has shown that forest size matters to these insects, so I used GoogleEarth to pre-select the largest forest blocks to visit in each county. I began in my childhood home county of Marshall and found no cicadas, either in forests on sandy soils or on the glacial moraine east of Lake Maxinkuckee.

I proceeded to Fulton County, just south of Marshall. I stopped beside County Road 450N east of US31, turned off the car motor, and listened. Could it be? Yes, I was hearing a chorus of “pharaoh,” the calling song of Linnaeus’s 17-year cicadas, Magicicada septendecim. I made a recording and continued down the road. I was gratified to find an entrance to Richland Restoration Park, which had trails into the forest. Newly emerged cicadas were resting on vegetation beside the trail.

The orange line between eye and wing separates septendecim from the other 17-year cicada species.

Shrubs with the cicadas were frequent along the trail.

Though one little area of 3-4 square meters had 25 cicadas, much of the way along the trail had none.

My overall impression was that these cicadas still were short of their peak, and I intend to return. I want to get some idea of how big this population is, how extensively it covers its forest, and whether any of the other 17-year cicada species also will emerge. Without the frequently more numerous Cassin’s 17-year cicadas (M. cassinii) to buffer them from predators, can the septendecim persist? In any case, I was pleased to find that at least one genuine Brood X remnant hangs on in my region. I still have a few more counties to search.

As the county road designation indicates, the park is 4.5 miles north of Rochester. It is closed on Wednesdays and the second Saturday of each month. The cicadas will be done before the end of June.

A New North for Jumping Bush Crickets

by Carl Strang

We are getting into the latter part of the singing insects season, and I have some catching up to do here. This time, just a quick note to update the northward advance of jumping bush crickets. This species has been spreading more rapidly than any others of our native singing insects. The Fox River has been my focus in recent years, as it appears to be a corridor they are following. The next county I expected them to reach was McHenry, and this year for the first time I found a population in the city of Algonquin in southern McHenry County.

Jumping bush cricket

I first heard jumping bush crickets in southern Kane County (immediately south of McHenry) in 2012. They have covered the 30-mile length of that county in 8 years. If they continue at that rate, they will reach the Wisconsin border in 6 years or so.

The red dot indicates the new location in McHenry County.

Their songs remind me of little bells tuned to slightly different pitches, and are loud and easy to hear as the males sing from hidden perches in trees, vines and shrubs. Here is a recording featuring jumping bush crickets:

Flagging in the Heat

by Carl Strang

On Saturday I completed my survey of 2020 periodical cicada reproduction in the Chicago suburbs. I focused on 18 suburban cities where I had observed wave chorusing, mapping out walking routes where I counted the flags that indicate where female cicadas deposited eggs in tree and shrub twigs. Altogether I walked 33.4 miles on hot afternoons, but the main physical challenge was the stiff neck I developed from constantly looking up into the trees. I will need to consult with periodical cicada specialists to be sure, but it seems to me that the numbers support a persistent, parallel splinter regional population that will continue to appear 4 years ahead of each major emergence.

Here I will share two sets of data. First, the highest numbers of flags in single trees.

Map of Chicago suburbs I surveyed for periodical cicada reproduction. Numbers indicate the highest count of flags in a single tree. Flags are withered twig ends that result from female cicadas inserting their eggs and cutting off the twig’s vascular system.

The high count of 33 was in Brookfield. I was walking residential streets, so my counts are transects rather than area surveys. The next map gives average numbers of flags per 100 meters. I used that number as the divisor because I often observed 1-2 wave choruses per block while driving earlier in the season, and 100m represents a middle-of-the-road block length.

Average counts of flags per 100m in Chicago suburb survey routes.

The highest counts of 10.5 and 9.1 are in LaGrange and Western Springs, respectively. These counts are conservative: I usually could not see all sides of a tree, canopies blocked part of the view, and to an unknown but certain degree flags had fallen to the ground and were removed by homeowners (this takes away some eggs, but there are others in the twig above the break).

Flags fallen to the ground at Madison Meadow Park, Lombard. In a residential yard these likely would have been removed before I could count them.

This fallen flag carried some eggs, leaving others still on the tree. Sugar maples were a popular choice by female periodical cicadas.

In addition to these transects in the cities, there were isolated parks and sites worth considering. At Pioneer Park Forest Preserve in Naperville, a single isolated non-wave chorus tree produced 7 flags spread between two trees. A similar case at Cook County’s Bemis Woods produced 18 flags. A park in Downers Grove had 37 flags. Other forest preserves had enough flags to suggest that their local off-year populations will continue: 22 at Lyman Woods, 13 at Greene Valley, and though I was disappointed by the size and timespan of the wave chorus at Wood Dale Grove, there were well over 30 flags there.

Tree with flags at Pioneer Park

First Flags Over Brookfield

by Carl Strang

Cicada specialist John Cooley taught me a new term: flagging. This refers to dead and broken twig ends on trees and shrubs where periodical cicadas have placed their eggs. Mama cicada slits the underside of the twig in several places and injects her eggs. This impedes water flow, and with circulation cut off the leaves turn brown. The cuts weaken the twig, and it may break partly and bend down, producing a “flag.”

Now that the periodical cicadas are done singing in many places and nearly so in others, it is time to start looking for these flags. They will provide the best measure of how this off-year emergence may continue for another generation. On Tuesday I started in Brookfield, the first place where I heard a full wave chorus of singing males.

I soon found a tree with many flags.

This tree was in the same place where I found that initial wave chorus.

The brown, drooping flags stand out against the green foliage. This prunes the tree a bit but will not cause significant harm. I saw many trees with one or two flags, but only the two in the photos had many. I expect to see more of them the next time I check.

John said that dry weather and thunderstorms enhance flag formation. A lack of water flow enhances the twig-end drying, and the buffeting winds of storms partially snap the weakened twigs. I heard no singing cicadas in Brookfield, and so this is the very beginning of this process. On the way home I swung through northern Hinsdale, another area that had abundant wave chorusing at the peak. There still were many small non-wave choruses, so it was not surprising that I saw only a couple flags during the drive-through. I am hopeful that flagging will develop over a period of weeks, allowing me the time needed to get a good assessment of periodical cicada reproductive success across the Chicago area this year.

« Older entries

%d bloggers like this: