Landscape Ecology of Singing Insects 3: Changes Over Time

by Carl Strang

Some of the formalism developed by landscape ecologists clarifies the current status of our singing insects and their prospects for survival. From the standpoint of a given species, the landscape is viewed as patches of habitat imbedded within a matrix of non-habitat. If that matrix is hostile to the species, the habitat edge is a “hard boundary,” and unless the species is good at dispersing long distances, they will be confined to their habitat island. To different degrees that extreme may not be met if there are steppingstones or corridors that can act as acceptable temporary refuges for dispersing individuals. I suspect that such is the case with pine tree crickets, for example. These habitat specialists are common in conifer groves across the region, many of which seem too isolated for such a small, specialized insect to cross the intervening distances. Nancy Collins, a Wisconsin specialist on the subfamily, has noticed that pine tree cricket nymphs can live, at least temporarily, in non-conifer, herbaceous habitats. Edges of conifer groves thus are not hard boundaries for pine tree crickets. In other cases, river corridors and highway rights-of-way can serve as travel lanes. Thus, the little-known dispersal abilities of our various species are key to understanding their status.

Pine tree cricket

In some of the crickets and katydids which normally are short-winged and flightless, long-winged morphs occasionally appear. Roesel’s katydid, mentioned in the previous post, essentially is never long-winged in its native Europe, but commonly is so here, where the species is expanding its range. There is a tradeoff in play for such species. Long-winged variants are good dispersers, but their fecundity is reduced.

Roesel’s katydid, long-winged variant

Dispersal also can be facilitated by humans. I have seen examples, with Japanese burrowing crickets and jumping bush crickets, of individuals and small groups showing up far ahead of the front of their range expansion, in places where landscape materials are stored or sold.

Mate finding motivates some movement by singing insects. The females in general must travel to meet up with singing males. The males themselves also may need to change their position. In DuPage County, where swamp cicadas are relatively few and scattered, I have observed males frequently changing position between songs by tens of meters at a time. An Iowa study (Shaw, Bitzer and North 1982) found that sword-bearing coneheads shifted position an average of 6.2m between nights, but otherwise remained associated with their group of other males.

Swamp cicada

The singing insects whose habitat needs are met by landscape alterations for agriculture and residential areas are the abundant, widespread ones. They are easily picked out by the large number of sites marked on their maps in my singing insects guide. Dispersal is relatively easy for them as there are large habitat blocks well connected by amenable corridors. Even they can suffer local extinction as land is cleared of vegetation for buildings or roadways. As new vegetation grows into such places, the weedy species are quick to re-establish themselves, but this underlines the dynamism of the habitat patch mosaic.

Of greater interest, and greater concern, are those species whose needs are not met by human-created habitats. Here the habitat patches are only a small percentage of the landscape, and elements of patch size, patch isolation, and insect dispersal ability become critical to understanding. Theory suggests that when a habitat falls below 10-20% of the landscape, dispersal ability is expected to drop dramatically in the absence of viable corridors or steppingstones; such is certainly the case for many of our habitat specialists. A few species anecdotally are good dispersers. I have reports, or have seen myself, instances of slender meadow katydids and long-tailed meadow katydids showing up in locations remote from their respective habitats. These individuals were unusual among the small meadow katydids in being long-winged morphs; most cannot fly.

Slender meadow katydid

Patch isolation in some cases is such that successful dispersal is impossible. Distances among the few surviving sphagnum bogs, for example, are too great to be crossed by sphagnum ground crickets. Prairie cicadas can fly, but apparently are disinclined to do so far enough to matter. At one of their sites, the West Chicago Prairie in DuPage County, they remain confined to one area of mixed grasses and forbs. They have not crossed the 350 meters of grasses, small shrubs and wetlands that separate them from a similar area within the same preserve. So far, their populations have persisted in remnant prairies ranging from 1 to a few acres. Can such small populations survive long term?

Prairie cicada

That question raises another concept from landscape ecology: extinction debt. This is the idea that a species’ habitat may have been so reduced that it still may be present but is doomed to fade away to extinction because its numbers are inadequate to maintain reproductive viability. Such may or may not be the case for prairie cicadas. I suspect this is what happened to northern wood crickets (NWC) in the region. NWC were known from two forested areas in northern Indiana at the beginning of the 20th Century (Blatchley 1903). One of these was in Marshall County. Years ago I used the original survey notes and county soil map to reconstruct the presettlement landscape of the township in question.

Presettlement map of Union Township, Marshall County, Indiana. Mesic forest was the large green area east of Lake Maxinkuckee.

Blatchley found NWC in the area of mesic forest which, in 1834, was very large. By the end of the 19th century agricultural clearing would have been well under way, and today only a tiny portion of that forest remains, the rest having been converted to pasture and crops. The same is true of forested areas in Lake County, Indiana, the other area where NWC lived in the late 1800’s. Though fragments of the forests where Blatchley found NWC remain, the crickets are gone, and I have checked all the other relatively large forests in the region without finding them. This raises the disturbing question: how many other species presently in the Chicago region are in a state of extinction debt? Patch size needed to maintain a species is dependent upon the characteristics of the species, its population dynamics, and patch quality. These are unknowns for all the uncommon species.

Our two species are Linnaeus’s 17-year cicada, on the left, and Cassin’s 17-year cicada, on the right

I will close this section with a case study on the periodical cicadas in DuPage County. In pre-settlement times the county was, from the cicadas’ perspective, a matrix of prairies and wetlands with 18 forested areas of various sizes scattered throughout. Historical maps and aerial photos allowed me to trace changes in those forests from the early 19th Century to the present day. I measured the forest sizes, noting their smallest (bottleneck) extents and how those were reflected in the presence of periodical cicada choruses in the 2007 emergence. There was a clear threshold of local extinction: forests which had remained above 61ha (hectares) still had cicadas, those which had fallen below 52ha did not, even when they had grown larger subsequently. Old newspaper accounts placed cicadas in at least some of these. Three forests which fell between those sizes appeared to have been affected by isolation, a remote one lacking cicadas, and two near persisting populations having them. The human history peculiar to the county is important here. DuPage County is immediately west of Chicago. The western half of the county quickly became agricultural, with forests cut back to make room for fields and pastures. Forests lacking cicadas in 2007 were mainly in the west. The eastern half developed residential commuter communities, with forests being protected and expanded as people planted trees around their homes. The largest area with cicada choruses in 2007 was lobular in shape, the various lobes following the routes of commuter-serving railways and the towns that expanded along them, connecting several of the pre-settlement forest locations. When the cicada choruses reached their peak in the first half of June, numbers of the insects suddenly appeared in flight, crossing over highways and other hostile environments. Subsequently, small groups showed up in places remote from the concentration areas. Whether these will result in significant expansion of the species in the county remains to be seen, but this observation supports the notion that competition and population pressure produce responses by the cicadas. They have the advantages of stronger flight capabilities and better vision than other singing insect groups.

Landscape Ecology of Singing Insects 2: Human Influences

by Carl Strang

The previous post illustrated that the Chicago region has been a dynamically changing landscape through the recent millennia, but that now is overshadowed by the alterations our own species has made. Burgeoning human numbers have overwhelmed the planet’s ecosystems, and the native habitats described earlier mostly have been replaced by agriculture and urban growth in the Chicago region. One of the more dramatic changes is the loss of the Kankakee wetland, once described as the Everglades of the North. That vast wetland was drained for agriculture, and only a few pockets of it survive in preserves. Much of the Kankakee River in Indiana is now a straight channel with constructed high levee banks. Other smaller wetlands received similar treatment, with drainage ditches spreading across the agricultural portion of the region. This is not universally devastating to wetland species. Northern mole crickets, for instance, occasionally can be found along drainage ditches.

Drainage ditch, upper reaches of the Kankakee River, St. Joseph County, Indiana. Note farm fields on both sides.

Prairie mostly has been replaced by agricultural fields, and fire suppression has led to its invasion by woody plants. Specialists such as the prairie meadow katydid, prairie cicada and short-winged toothpick grasshopper are hard to find.

Prairie meadow katydid

My singing insects research has required a lot of driving to reach the relatively tiny surviving preserves and parks to which many of the species are now restricted. Much management effort is required in these little islands to maintain their habitats. There are exceptions, of course. Many other species have thrived under our influence. These are mainly weedy ones such as the striped ground cricket, short-winged meadow katydid and Carolina grasshopper, which do well in disturbed habitats, along with woodland edge species such as the greater angle-wing, snowy tree cricket, and jumping bush cricket, which can meet their needs in residential neighborhoods dominated by lawns and scattered trees and shrubs.

Jumping bush cricket

Habitat destruction is not the only human influence. Climate change is the probable cause of northward range expansions by several singing insect species, and it likely will lead to the extinction of the sphagnum ground cricket from the region as the sphagnum bogs dry up. Say’s cicada and some northern grasshoppers already appear to be pushed out.

Sphagnum ground cricket

Climate change isn’t simply a matter of rising temperatures, as the term “global warming” may seem to imply. Global warming is an accurate enough term, as the simplest way to measure climate change is to track the global average temperature. But the point is that our changes to the Earth’s thin skin of atmosphere are increasing its held solar energy. That energy alters patterns of atmospheric flow and the behavior of storms. Droughts, more frequent flood-causing rains, and seasonal increases or decreases in temperature that seem abnormal are examples of results we observe locally. The singing insects are forced to adjust as best they can. Droughts force sphagnum ground crickets into the wettest parts of their bogs. The severe drought of 2012 concentrated wetland meadow katydids and marsh coneheads into the small portions of the Great Marsh in the Indiana Dunes National Park that remained wet. Oblong-winged meadow katydids may be pre-adapted to such year-to-year variability. Blatchley (1920) observed that their eggs, laid in moist soil, can take 2-3 years to hatch. In my travels through the region I failed to hear a single individual in the years 2010 and 2019, but in other years they have been abundant and widespread. Some of the cicadas and other species may have similar flexibilities.

Oblong-winged katydid

People also have introduced plant species from other parts of the world which, released from the consumers and competitors which hold them in check in their native lands, have become invasive plants here. Their unfair competitive advantage has led to their displacing the region’s native vegetation in an increasing number of places. This is most evident in our wetlands. Wetland meadow katydids and other singing insects are limited to places where native wetland grasses have not been supplanted by reed canary grass, common reed, purple loosestrife, and hybrid cattails. These invasive plants are proving difficult to control, and the outlook is not good for species such as the dusky-faced meadow katydid and marsh conehead. To my knowledge the once relatively widespread stripe-faced meadow katydid now is confined to a single site, and the slender conehead, never known from many locations, apparently is gone from the region.

Stripe-faced meadow katydid

Introductions have not been limited to plants. Several species of singing insects also have been imported. Roesel’s katydid is the most common of these in our region. A European predaceous katydid, Roesel’s was introduced to the Montreal, Quebec, area several decades ago and expanded from there. They occur in open habitats with tall herbaceous vegetation throughout the Chicago region. Japanese burrowing crickets are thought to have arrived at the port of Mobile and spread out from there. They are abundant as far north as Indianapolis, and common in Rensselaer in the southern part of our region. With scattered new appearances each year occurring as far north as DuPage County in Illinois, so far, I expect them to become widespread and abundant here. The tropical house cricket represents the possibility of other, short-term introductions that are unlikely to persist in our climate.

Roesel’s katydid

Lulu Lake

by Carl Strang

During a 3-day Wisconsin trip last week, I made a lot of stops in Racine, Walworth and Kenosha Counties, the most remarkable of which was a state natural area, Lulu Lake, in Walworth County.

The site includes a large, high quality bog.

The site includes a large, high quality bog.

For once, the songs of the sphagnum ground crickets were not buried among those of Say’s trigs, as has been true at other bogs I have visited.

The bog is surrounded by hills of glacial outwash gravel.

The bog is surrounded by hills of glacial outwash gravel.

Those hills held two species I have not observed elsewhere in Walworth County to date: tinkling and spotted ground crickets. The former seem to prefer dry woodland edges on well drained sandy soils. The latter like moist shaded spots in woods on well drained sandy soils.

The bog is reached from the south by a long walk through a meadow with a good percentage of prairie plants. This curve-tailed bush katydid was a resident of that meadow.

The bog is reached from the south by a long walk through a meadow with a good percentage of prairie plants. This curve-tailed bush katydid was a resident of that meadow.

One more photo from the Wisconsin trip comes from an Interstate rest stop, also in Walworth, where I found my first straight-lanced meadow katydids for that county.

Nancy Collins had remarked that the straight-lanced males on her site had brown cerci. Going back, I find that this is true of every male I have photographed over the years.

Nancy Collins had remarked that the straight-lanced males on her site had brown cerci. Going back, I find that this is true of every male I have photographed over the years.

This was a very productive trip, resulting in 22 county records for the three days.


Return to Berrien

by Carl Strang

Earlier this season I scouted some new sites in Berrien County, Michigan, and on Sunday I returned to see what singing insects I could find in the early portion of the peak season. A first quick stop at Mud Lake Bog produced a hoped-for population of sphagnum ground crickets, and I was reminded how utterly teeny tiny they are.

Most of the day, and a return trip in the evening, went into a place in the eastern part of the county called Chikaming Township Park. If this were Illinois, I wouldn’t expect much from a park district administered at the township level, but this is a good and well maintained site, and it yielded a pile of county records for my study. One of these was provided by a female curve-tailed bush katydid that flew to a landing right in front of me on one of the trails.

The dark-tipped green ovipositor with this shape and proportions, along with the katydid’s overall size and the habitat, permitted the identification.

The dark-tipped green ovipositor with this shape and proportions, along with the katydid’s overall size and the habitat, permitted the identification.

After release, she hung around long enough to let me take a single usable, if not absolutely sharp, photo.

After release, she hung around long enough to let me take a single usable, if not absolutely sharp, photo.

Perhaps the most bizarre observation came as a result of the day’s odd weather. I drove through intermittent rain to get to Berrien County, and waited out the last shower before going out onto the Mud Lake Bog boardwalk. Dark clouds remained until mid-afternoon, but they slowly drifted east and the sun was revealed at 4:00 local (eastern) time. Almost immediately, Chikaming’s swamp cicadas began to sing. These generally are limited to mornings, but here they were going in the late afternoon. This site proved to have the largest concentration I have encountered to date. At one point I wandered into a song battle taking place among a trio of males in a meadow with scattered tree saplings. One allowed a close approach.

None of our other cicadas matches the swamp cicada’s heavy black coloration.

None of our other cicadas matches the swamp cicada’s heavy black coloration.

Later in the evening I was able to pick up some additional species.

Among them was this Forbes’s tree cricket.

Among them was this Forbes’s tree cricket.

The highlight of the day, though, came at another site, Galien River County Park. I had set a goal for this season of listening for spotted ground crickets, which historically have been documented in several Chicago region counties, but which I had not noted to date. Described as a forest species, the spotted ground cricket’s song to my ear is similar to that of a common and widespread species, the Carolina ground cricket. I realized that while some of the forest crickets at Galien River indeed were Carolina ground crickets, others sounded a little different. I made recordings, and listened carefully, and was pleased to conclude that spotted ground crickets were there as well.

An example of a spotted ground cricket location.

An example of a spotted ground cricket location.

The songs have a similar tonal quality and pitch range to my ear. Where the Carolina ground cricket’s song is a steady purr with intervals of added overtones, the spotted ground cricket’s song is composed of regular pulses (about 4 per second), has no overtones, and lacks the continuous steady sound.


Sound Ideas: 3 Ground Crickets

by Carl Strang

Today I share recordings of 3 ground crickets. The first of these, the melodious ground cricket, is not very well studied, and recordings of its song are not commonly available.

Melodious ground cricket

Melodious ground cricket

The song is a fairly loud, steady trill with a pleasant tone:

That song is most like that of Say’s trig, which can occur in close proximity as both are wetland species. When such is the case, the distinction is clear. Here is a recording of Say’s trig for comparison:

The recordings are a little misleading in that both species can be equally loud. Next up is the sphagnum ground cricket.

Sphagnum ground cricket. This species does not occur away from sphagnum moss.

Sphagnum ground cricket. This species does not occur away from sphagnum moss.

The song is higher pitched and more rapid than that of Say’s trig, which again often co-occurs.

The final species has an interrupted trill, unlike the continuous singing of the previous crickets. The confused ground cricket usually is found in drier portions of woodlands than the more swamp-dwelling melodious ground cricket.

Confused ground cricket

Confused ground cricket

The song is about one second on, one second off. If there are few other sounds, you may hear some stuttering during the “off” intervals:


Sometimes It Gets Messy

by Carl Strang

I haven’t been posting here lately, as I have been busy writing summaries and reports on the past season of my singing insects study. As 2014 was a good, productive year, this has been a time consuming process. The discovery of variegated ground crickets in October brought a new complication, as their song superficially resembles those of several other crickets, including Say’s trig and a few other ground crickets. I decided to review all of my relevant recordings and re-analyze them to discover distinguishing features. Two quantities that researchers have discovered to be significant in singing insects are dominant frequency (pitch or highness of the tone) and pulse rate (the speed at which wings open and close to produce the song). These are determined by sonographic analysis of the recordings in the computer. The plot of all the recordings looks like this:

Hence “messy” in this post’s title.

Hence “messy” in this post’s title.

The colors represent my decision as to species (usually I did not see the singer): red for Say’s trig, green for variegated ground cricket, blue for gray ground cricket, black for sphagnum ground cricket, and yellow for Cuban ground cricket. The shapes represent one of three ways in which these crickets begin their songs: square for an abrupt start (or for unknowns, cases in which the recording did not include the start of a trill), triangle for a crescendo from low volume to the extended peak of loudness, and circle for a start that often is rendered “chuwee.” The last has an abrupt beginning, but immediately has a momentary drop in pitch or volume that as quickly is followed by the continuous, full volume trill. All these crickets end their trills abruptly. Empty centered shapes are for recordings that were noisy or in which more than one individual was singing, potentially leading to a false reading. The numbers are the temperatures in degrees Fahrenheit, when known.

Ideally, there would be well defined clusters of points separating the represented species. This did not happen, and I can identify a few reasons. In some cases, the recording’s quality was compromised (the hollow-centered shapes). Temperature can affect song qualities, and there is no single established threshold for all species, below which recordings become ambiguous. Also, some features of songs are not in the graph, notably the length of trills, and the length of pauses between them.

The outlier for variegated ground crickets, the green triangle with the lower frequency and pulse rate, was the recording I made indoors. I only kept that cricket for one night, and had it in a cage with only a few leaves on its floor. I have more trust in the values for the Cuban ground cricket, which was well established in a beautifully furnished terrarium at Lisa Rainsong’s home in the Cleveland suburbs, where I stopped briefly on my way to my brother’s for Thanksgiving (thanks again, Lisa!).

Here are my tentative conclusions from this analysis:

First, I need to make a lot more recordings, with care to note habitat, temperature, and whether the singer is on the ground or height above the ground. I need to isolate one singer from all others, with the microphone as close to it as possible. Better habitat conditions are needed to get good response for indoor recordings.

So far, dominant frequency, habitat, and how the trill starts are more helpful than pulse rate in distinguishing these species.

Say’s trig songs are characterized by a chuwee start, a location above the ground, and a lower pitch (usually 7.5kHz or less). Trills may be long or short, but when short usually are in rhythmic bouts.

Variegated ground crickets consistently have crescendo starts, trills usually less than a minute long, and pauses between of at least several seconds. Field recordings had high dominant frequencies (8.6 kHz or above).

One Cuban ground cricket recorded indoors had a pattern like that of the variegated, but a lower dominant frequency (7.6 kHz). From Lisa’s description, these two species occur in very similar habitats, but the Cuban ground cricket is more likely to be found on the surface of the ground. Variegateds occupy soil cracks or other buried locations.

Gray ground crickets have abrupt starts and only brief-moment pauses, with dominant frequencies of 8.0-8.9 kHz. They occur in dry sand soils.

One recording of a sphagnum ground cricket has a high dominant frequency (8.5 kHz), plus a chuwee start. It occurs only in sphagnum bogs, but potential associates include Say’s trig and variegated ground cricket, which can be distinguished, respectively, by their lower dominant frequency and crescendo starts.

That’s enough for now. I plan to share some of these recordings in future posts.

Sound Ideas: Gray Ground Cricket

by Carl Strang

In the vegetation that grows just behind the beaches around the western Great Lakes you may hear a very rapid, high-pitched trilling sound, as in this recording I made at Whitefish Point (on the north side of the tip of Michigan’s Upper Peninsula) on September 16, 2009:

The area where the previous recording was made.

The area where the previous recording was made.

This interrupted trill is identical to the reference recording for the gray ground cricket on the Singing Insects of North America website. Indeed, this species is expected in open, sandy soil habitats. The only other ground cricket song I have heard that is close to this is that of the sphagnum ground cricket, which is restricted to sphagnum bogs and could not survive on sand. Allard’s ground cricket, when it occurs with the gray ground cricket, has a distinctly slower song.

The challenge for me with this species has been two-fold. First, I have never seen one. Second, I am pretty sure they occur inland as well. Here is a recording from Braidwood Dunes, a Will County Forest Preserve, September 7, 2011:

At the time I noted that there were pauses, but enough crickets were singing simultaneously that these are difficult to pick out in the recording. I have heard, and sometimes recorded, this same song in other inland locations in Kendall, Marshall and Fulton Counties. Sometimes the pauses are infrequent or nearly absent, but the songs all have a peak frequency of 8-8.5 kHz, and share similar patterns of amplitude irregularity in their sonographs. I am not aware of any other cricket that could occur in dry soils with a song like this. Furthermore, there are some mentions of inland gray ground crickets in the literature, and some authors refer to the trill as continuous. So, mainly by process of elimination I have decided to refer to all these crickets as gray ground crickets for now, but with a higher priority of catching one, particularly at one of the inland sites, for confirmation.

National Lakeshore Wetlands

by Carl Strang

After catching the melodious ground cricket I drove to Pinhook Bog, a part of the Indiana Dunes National Lakeshore that is open to the public only on rare occasions. I hoped to find stripe-faced meadow katydids, but the bog’s public access boardwalk was bordered by little in the way of grasses and sedges. I was gratified, however, by the presence of sphagnum ground crickets.

These were the first I have found in Indiana. I have seen them only at Volo Bog in Illinois.

After lunch I returned to the place where Gideon, Nathan and I caught the marsh coneheads in early August. Gideon had relayed the news that some of the meadow katydids Nathan also had caught there were dusky-faced, one of the conservative species I had yet to find. The lead paid off.

The legs were totally green, unlike those of the familiar black-legged meadow katydid.

I caught a couple individuals to hold for close-ups.

The head of the dusky-faced meadow katydid is amber colored, with fine dots and lines of red-brown.

While wading the tall grasses and sedges I also spotted a different large meadow katydid with green legs and a beautiful yellow-green face.

Unfortunately I only saw the one, and the auto-focus on the camera frustrated my attempts at a clear photo before she flew away. Though blurred, the image provided enough information for identification.

This was another species on my conservative wetland singing insects want list: the delicate meadow katydid. So, what was so special about this place?

View of the edge of the portion of the Great Marsh under discussion.

For one thing, invasive Phragmites was absent, and cattails were limited to a few scattered plants. Grasses and sedges were the dominant plants. Black-legged meadow katydids were very few, and limited to the dry-soil edges of the wetland. The plants and katydids were zoned. Just inland from the water and mud-flat edge was a zone of shorter, finer grasses in which the only singing insects I saw were abundant slender meadow katydids. Then came taller grasses of intermediate coarseness, where the dusky-faced and delicate meadow katydids were, along with a few marsh coneheads.

Female marsh conehead

The soil became progressively less water saturated as the vegetation rings went outward. Next came a zone of very coarse sedges. The only species I saw in there was, surprisingly, a long-tailed meadow katydid (a tiny species dwarfed by the big triangular sedge stems).  Interspersed here were patches of taller grasses which contained more dusky-faced meadow katydids. This area gave me a strong image of good marsh habitat to carry as I continue to search for these insects in other places.

The Meaning of “Range”

by Carl Strang

This is the third installment of a weekly series on singing insect species that supposedly occur in northeast Illinois or northwest Indiana but which I have yet to find after several years’ field work. Today I will consider two crickets representing different groups. They have in common a certain peculiarity in their range maps. We’ll start with the melodious ground cricket.

As you can see, the shaded area on this map (from the Singing Insects of North America website, or SINA) places nearly all of Illinois within the range of this species. However, that shaded area is computer generated from the only concrete records, which are represented by the black dots. Note that there are no dots anywhere in Illinois. As far as the SINA database goes, the species never has been found in Illinois, and there are only two records from northern Indiana. Illinois is included in the range thanks to a single record from northern Missouri. The species first was described from Ohio in 1957 by Edward S. Thomas and Richard Alexander. It is very similar to the Carolina ground cricket physically, but its song is described as a more melodious trill (lacking the Carolina’s discordant overlay of tones), and its habitat is narrower, limited to bogs and marshes. Even in Ohio there are few locations. The map shows melodius all over Florida, where Thomas Walker (who runs the excellent SINA site) is located.

The next example is the prairie tree cricket.

Northeast Illinois and northwest Indiana are included in the range for this species thanks to two records for Cook County, Illinois, from 1934 and 1935. On the other hand, two records from Iowa probably would have led the computer to shade our region even without those old Cook County records. I mentioned in an earlier post this year that I am looking for prairie tree crickets in sweep samples from meadow and prairie areas, but so far have found only four-spotted, and black-horned/Forbes’s tree crickets in that sampling.

These examples underline the need to be careful in thinking about the geographic range of species. Some singing insects are relatively general in their habitat choice, or tolerant of human alterations in the landscape, or simply have been fortunate to have passed through the sieve of history unscathed. They are the common ones. Shaded areas in range maps like SINA’s represent them best. Other species are much pickier, or their lower densities have made them subject to more frequent local extinctions over time. They are best represented by dots. The best example I have encountered here is the sphagnum ground cricket, which appears indeed to be limited to the narrow confines of sphagnum moss areas. These were more ubiquitous in the broad zone which trailed the last continental glacier north, but then in southern parts became isolated in little bits here and there.

I am not removing melodious ground crickets or prairie tree crickets from my hypothetical list for our region, but until I find them I will not list them as definitely occurring here today.

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.

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