Broad-winged Tree Crickets 2015

by Carl Strang

The broad-winged tree cricket was the first singing insect species I found (in 2006, the first year of my study) that had shifted its northern range boundary significantly.

Broad-winged tree cricket

Broad-winged tree cricket

In contrast to the jumping bush cricket, this one seems to be moving slowly, but I have not followed it as closely. This year I put some time into locating northernmost singers, and found two locations.

Chicago region map of broad-winged tree cricket locations. Black dots mark counties where I have found the species to date. Red stars indicate specific locations where I found northernmost crickets singing this year.

Chicago region map of broad-winged tree cricket locations. Black dots mark counties where I have found the species to date. Red stars indicate specific locations where I found northernmost crickets singing this year.

These will be the starting points for next year’s check. The Kane County location is only 1.5 miles south of the southern McHenry-Lake County border line.

Sound Ideas: Trilling Tree Crickets

by Carl Strang

Today I wish to share recordings of 4 species of our tree crickets, which have in common songs that are continuous (rather than interrupted) trills. I will order them along a typical habitat gradient, from grasses to mixed grasses and forbs to mixed forbs and shrubs to trees (specifically, conifers).

The four-spotted tree cricket seems to prefer to sing from grass stems.

Four-spotted tree crickets are pale.

Four-spotted tree crickets are pale.

The song is a continuous clear trill:

Very abundant late in the season, Forbes’s tree cricket prefers forbs or vines.

Forbes’s tree cricket is highly variable, but usually has some dark markings.

Forbes’s tree cricket is highly variable, but usually has some dark markings.

Here is a recording from last year:

There is an interesting issue surrounding these first two songs, in my mind. I know of other singing insect students who, like me, at least sometimes can distinguish the songs of four-spotted and Forbes’s tree crickets, but we describe them with different language. To me, the four-spotted’s song has more of a clear, tone-like quality, while the Forbes’s song has a discordant tone that others apparently don’t hear. Others point to the difference in pulse rate (much faster in Forbes’s, but I need a computer analysis of a recording to tell that difference). This is the best example I have found of how describing insect songs in words can be difficult, and may in some cases be impossible.

Woodland shrubby understories to masses of forbs in open places near wooded edges are habitat for our third species, the broad-winged tree cricket. Here is its song:

Broad-winged tree crickets are distinguished by the wide wings and the raspberry coloration on the head and antenna bases.

Broad-winged tree crickets are distinguished by the wide wings and the raspberry coloration on the head and antenna bases.

To my ear, this song has a richer tone, and usually is lower in pitch than other trilling tree crickets at the same temperature.

I’ll close with the pine tree cricket, perhaps the most beautiful of the four.

The red-browns and pale greens provide good camouflage in a habitat of coniferous trees.

The red-browns and pale greens provide good camouflage in a habitat of coniferous trees.

The following recording was made indoors, from a caged male (you can hear the splashing of the aquarium pump in the background):

Again the trill is continuous and similar to the others, especially the four-spotted tree cricket, but the source of the sound in a pine, spruce or cedar (usually in a grove of them) is a dead give-away.

Seeking Northern Limits: Broad-winged Tree Cricket

by Carl Strang

The broad-winged tree cricket was the first singing insect that surprised me by turning up north of its established range. That was back in 2006, and finding it abundant in DuPage County, half a state north of where it previously had been known to occur, was my first indication that there were significant gaps in knowledge that needed filling.

Broad-winged tree cricket

Broad-winged tree cricket

Since then, I have determined that this cricket becomes somewhat less abundant as one moves south to north in DuPage, but there are places where choruses of many individuals can be heard in the northern third of the county.

 In addition to the wide wings, this species has raspberry-colored basal segments in its antennae.

In addition to the wide wings, this species has raspberry-colored basal segments in its antennae.

Dorsal view of the same. I released this fellow after taking the photos.

Dorsal view of the same. I released this fellow after taking the photos.

This year I put some time into seeking broad-winged tree crickets to the north of DuPage County. I found them in two locations in northern Cook County: the Carl Hansen Woods Forest Preserve, where there are a few pockets of up to 20 singing males but much suitable habitat that remains empty; and, a little farther north, 3 singing males at Penny Road Pond, another Cook County Forest Preserve site. I sought them without success farther north.

The current known distribution of broad-winged tree crickets in the region.

The current known distribution of broad-winged tree crickets in the region.

I believe they still are spreading, and in fact a few years ago found them in southwestern Wisconsin at the junction of the Wisconsin and Mississippi Rivers. Documenting their spread will remain another item on my annual research checklist of goals.

The Other Side of Range Extensions

by Carl Strang

The aspect of singing insect studies that has been of greatest general interest, and about which I have presented talks most frequently, is range extensions. Most of the several examples uncovered so far have been northward extensions of species ranges, and it is easy to jump to the conclusion that this is a product of global climate change.

The first species I found well north of where it previously had been known was the broad-winged tree cricket.

The first species I found well north of where it previously had been known was the broad-winged tree cricket.

If climate is the primary influence in these range extensions, we would expect the southern boundary of a species’ range to shift north as well. However, sticking with the example of the broad-winged tree cricket, its range has expanded south as well as north. I know that only because Tom Walker, the authority responsible for the Singing Insects of North America website, informed me that he has found them spreading down into parts of Florida where they had not been before.

Documenting an expansion northward is easier than demonstrating a disappearance in the south portion of a species’ range. It is easier to prove a positive than a negative. Also, when one has limited time and financial resources, it is not possible to travel south and conduct the necessary regional surveys. So, what to do?

The best idea I have had so far is to identify species whose southern range boundaries occur in my region, and make a point of documenting their presence and estimating their abundance from year to year. There are four best candidates.

The dog day cicada Tibicen canicularis has the northernmost southern range boundary. It is mapped down into the very northern edges of Indiana and Illinois, but I have found it a little farther south, at Braidwood Dunes in Will County, Illinois, and in southern Marshall County, Indiana. My notes suggest that its numbers may vary considerably from year to year in the latter location.

Dog day cicada

Dog day cicada

The broad-winged bush katydid Scudderia pistillata is mapped a little farther south, but I have found it infrequent in DuPage County, Illinois, and its season of activity seems to conclude sooner here than it does farther north. So far my surveys have turned it up in Lake County, Illinois, as well, but not farther south.

Broad-winged bush katydid

Broad-winged bush katydid

The striped ground cricket and sword-bearing conehead are abundant in the region. Their southern range boundaries are mapped about half a state south, but that is the same distance as a number of the northern range shifts I have observed. If entire ranges are shifting, one would expect them to be more scarce.

Sword-bearing conehead

Sword-bearing conehead

This is yet another topic of interest I am keeping in mind while surveying the region’s singing insect species.

Singing Insects Range Extensions

by Carl Strang

My other presentation at Saturday’s Wild Things conference reviewed the range extensions by 8 species of singing insects that have turned up in our region in recent years. I ran through them in the chronological order of their discovery, and then offered some general points.

Broad-winged tree cricket (Oecanthus latipennis)

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Map from the Singing Insects of North America website (SINA), 2012. The record in DuPage County resulted from this study, and was added in 2006. Prior to that the species was not supposed to occur in the Chicago region.

Map from the Singing Insects of North America website (SINA), 2012. The record in DuPage County resulted from this study, and was added in 2006. Prior to that the species was not supposed to occur in the Chicago region.

Original range sources: Hebard 1934  (“Northern limits of distribution are Hilliary and Quincy”), McCafferty & Stein 1976 described it as a central and southern species in Indiana, with Tippecanoe County the northern extent. I found them in DuPage County in 2006, and subsequently learned they are abundant throughout the county. They also have reached the junction of the Wisconsin and Mississippi Rivers in Wisconsin.

Jumping bush cricket (Orocharis saltator)

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Jumping bush cricket SINA map, 2012. The added red line indicates the northern range limit as of 1969, when Tom Walker reviewed the genus.

Jumping bush cricket SINA map, 2012. The added red line indicates the northern range limit as of 1969, when Tom Walker reviewed the genus.

Original range sources: Hebard 1934 (Shawneetown northern limit in Illinois; “should however be found throughout southern Illinois as it is known as far north as central Indiana”). McCafferty & Stein 1976 (“known only from the southern two-thirds of the state” with Tippecanoe County given as the northern limit). They are rapidly expanding in DuPage County, abundant in the southern half and spreading into the northern half with new northern limits found annually. I also have heard them at Indiana Dunes State Park.

Roesel’s katydid (Metrioptera roesellii)

Roesel's s-wing female Purdue b

Roesel’s katydid SINA map, 2012. Prior to work by Scott Namestnik and me, the range was thought to end in northeastern Ohio, with a small disjunct area in northeast Illinois. The red dots indicate our added findings in 2012.

Roesel’s katydid SINA map, 2012. Prior to work by Scott Namestnik and me, the range was thought to end in northeastern Ohio, with a small disjunct area in northeast Illinois. The red dots indicate our added findings in 2012.

Original range sources: Roesel’s katydid is a European species that in North America first was found in two suburbs of Montreal, Quebec (Urquhart and Beaudry 1953, Beaudry 1955), and is thought to have been introduced between 1945 and 1951. Vickery (1965), who summarized this history, reported that the species had spread into New York state and Vermont by 1965, and that the long-winged variants that originally had dominated the Montreal population were diminishing in favor of the short-winged forms typical of the European continent. The Montreal population apparently was by then limited by an indigenous parasitic nematode. Roesel’s reached Ithaca, NY, by 1965 (G.K. Morris, as reported by Shapiro 1995), and Long Island by 1990 (Shapiro 1995). Short-winged forms were dominating the St. John, New Brunswick, population by 2008 (McAlpine 2009), and so had arrived some unknown number of years earlier. Nickle (1984) reported finding them in Pennsylvania by the early 1980’s. Roesel’s katydids were collected in two northeastern Illinois counties in the late 1990’s (Eades and Otte, no date). I found them in north central Indiana in 2007, and subsequently Scott Namestnik and I have found them throughout northern Indiana (as far south as Indianapolis) northeast Illinois, and last year the Lower Peninsula of Michigan. Others have added Ohio, Wisconsin and eastern Iowa.

Round-tipped conehead (N. retusus)

Roesel’s katydid SINA map, 2012. Prior to work by Scott Namestnik and me, the range was thought to end in northeastern Ohio, with a small disjunct area in northeast Illinois. The red dots indicate our added findings in 2012.

 

Round-tipped conehead SINA map, 2012. The added red line indicates the northern extent of the range in Illinois in 1934 and in Indiana in 1976.

Round-tipped conehead SINA map, 2012. The added red line indicates the northern extent of the range in Illinois in 1934 and in Indiana in 1976.

Original range sources: Hebard 1934 (“Urbana is a northern limital point”), and McCafferty and Stein (1976) had none north of Indianapolis, but they are so common in northwest Indiana and northeast Illinois now that this is a well advanced range expansion in the intervening decades. I also heard a single singing individual in a meadow at Wyalusing State Park in Wisconsin in 2007.

Handsome trig (Phyllopalpus pulchellus)

Handsome trig 2b

Handsome trig SINA map, 2012. The northern dot at St. Joseph County, Indiana, is the result of Scott Namestnik’s work.

Handsome trig SINA map, 2012. The northern dot at St. Joseph County, Indiana, is the result of Scott Namestnik’s work.

Original range sources: Hebard 1934 (northern limits given as Marion County in Indiana and Monticello in Illinois; “confined to southern and central Illinois”). McCafferty & Stein 1976 indicated a northern extent in Tippecanoe County. In 2009 Scott Namestnik was posting photos of them from St. Joseph County.

Swamp cicada (Tibicen tibicen)

Swamp cicada 4AU 4b

Original range sources: This species was mentioned by Alexander, Pace and Otte in their (1972) Michigan singing insects paper, but they expressed doubt that it was a breeding species in the state. However, a later paper (Marshall, Cooley, Alexander and Moore 1996) reported finding it in extreme southern MI (intensive searching found it only in the southern portions only of the southern tier of counties. They were not willing to say whether this represented a range extension or the species being missed earlier). I first found it in Marshall County, Indiana, and DuPage County, Illinois, in 2010, but suspected I had heard it earlier. They are scattered across the southern half of DuPage.

Slightly musical conehead (N. exiliscanorus)

Slightly musical Max Wet b

Slightly musical conehead SINA map. This does not yet reflect our finding them in Porter and Marshall Counties, Indiana, in 2012.

Slightly musical conehead SINA map. This does not yet reflect our finding them in Porter and Marshall Counties, Indiana, in 2012.

Original range sources: Hebard 1934 (northern limits indicated as Tower Hill in south central Illinois, and New Harmony in Indiana). McCafferty & Stein 1976 (“In Indiana it is known only from heavy thickets and grasses along the Ohio River”). Gideon Ney, Nathan Harness and I, seeking slender coneheads, found this species at the Indiana Dunes National Lakeshore in 2012, and I found it in Marshall County as well.

Marsh conehead (N. palustris)

Slightly musical conehead SINA map. This does not yet reflect our finding them in Porter and Marshall Counties, Indiana, in 2012.

 

Marsh conehead SINA map. This does not yet reflect our finding them in Porter County, Indiana, in 2012.

Marsh conehead SINA map. This does not yet reflect our finding them in Porter County, Indiana, in 2012.

Original range sources: Hebard 1934 (“Lawrenceville and Carbondale are northern and western limits respectively for palustris…It is probably confined to the southern portions of Indiana and Illinois.”). McCafferty & Stein 1976 reported Tippecanoe County as the northern known extent. Ney, Harness and I found this species to be common at Indiana Dunes National Lakeshore and present in the state park.

General Points

Most of these range extensions are from south to north. Exceptions are Roesel’s katydid (east to west) and the broad-winged tree cricket (spreading south as well, according to SINA coordinator Tom Walker).

I do not know whether any other of these species likewise are spreading south or in other directions.

Some of these are clear range expansions, as they are species which were well known at the time of earlier studies, and now have become abundant beyond the range as then drawn: broad-winged tree cricket, jumping bush cricket, Roesel’s katydid, and round-tipped conehead.

The others have a spottier distribution, or may not have been as well known then, and so might have been missed by earlier researchers: handsome trig, swamp cicada, slightly musical conehead, and marsh conehead.

As for the possible connection between these range extensions and climate change, Gonzalez (2012) mentioned a calculation, based on work in Gonzalez et al. (2010), indicating that the region’s climate has undergone a temperature change equivalent to a southward shift in latitude of 100km in the 20th century. This is consistent with the magnitude of many of these observed range changes.

Learning to Identify Insect Songs

by Carl Strang

One of the obstacles to a singing insect monitoring program is the large number of various songs that need to be learned for identification. This is not really much different from learning bird songs for breeding bird monitoring, however (except that the total number of species is smaller here). Instead of being daunted by the entire process, it is possible to take the learning process in stages, beginning with the songs that are common and easy to recognize, the ones you have been hearing all along but simply didn’t have the species labels. Here is a list of a dozen suggested species to start with in the first stage: spring field cricket/fall field cricket (their songs are identical), Allard’s and striped ground crickets, snowy tree cricket, common true katydid, black-legged meadow katydid, greater angle-wing, round-tipped conehead, dog day cicada, scissor-grinder cicada, and Linne’s cicada (for more information on these species, try the tags at the head of this post).

Snowy tree cricket, one of the species on the starter list

This list and those that will follow are for northeastern Illinois and northwestern Indiana. There would be substitutions in other parts of the country (I encourage readers elsewhere to make comments here with their own suggestions). Go to reference recordings of these species’ songs, either on-line at the Singing Insects of North America website or through the CD that accompanies the Songs of Insects book. It is not too late this year to hear many of the species on this list on the warmer days, though some are finished or nearly so.

My recommended species list to focus on in the second stage of learning consists of 8 species and groups of species: greenstriped grasshopper, gladiator meadow katydid, Roesel’s katydid ( three species that sing relatively early in the season), and then later, Carolina ground cricket, Say’s trig, sword-bearing conehead, two-spotted/narrow-winged tree crickets (no need to worry yet about separating the two), and the meadow tree cricket group (3-4 species whose songs are essentially identical to the ear and will remain so).

Roesel’s katydid is a species from the second-stage list.

This list of common species either will take you to additional, though still readily available, habitats, or else require a little more of a practiced ear (which practice you got with the first species group). In particular, seek out and spend some time getting familiar with the songs of the Carolina ground cricket and Say’s trig. They need a little more effort to recognize in the field, but once you have them, they will be touchstones for many other species (much as robin songs are for learning bird vocalizations). If you are starting now, you might push the Carolina ground cricket to the first list, as it is one of the few species singing on the cooler days and evenings.

Once you have mastered the second list of species, you are ready for the more subtle distinctions needed to distinguish the songs in the third species list. This includes separating out the song of Linne’s cicada from similar songs by the lyric cicada, and in some areas, swamp and/or northern dusk-singing cicada.

Linne’s cicada

Also, by this point you are ready to distinguish the two-spotted tree cricket song from that of the narrow-winged tree cricket. Also, the broad-winged tree cricket should stand out now from other long-trilling species. In addition, you no doubt have noticed and begun to puzzle out other species that are more idiosyncratic in their distribution or smaller in numbers that you have encountered in your favorite places.

And that brings you to the fourth stage, learning the songs of whatever remaining species may live in the area you wish to monitor. For this you will need a regional guide. In the Chicago region, you can meet this need with the guide I am developing. It is available for free as a .pdf e-mail attachment. Simply request it at my work e-mail address: cstrang@dupageforest.com

As you are learning and listening, pay attention to which songs you can hear clearly, and at what distances, and which are marginal. This will inform the limitations you will need to address or acknowledge in your monitoring.

Forsythe Woods

by Carl Strang

Last week I provided a field training on singing insects for interpretive naturalists in Will County, a group organized the Nina Baki of that county’s Forest Preserve District. We started at Braidwood Dunes, finding the same species that I encountered in my first visit there a year ago, plus a few more. After an enjoyable dinner at a nearby restaurant, four of us went on to Forsythe Woods Forest Preserve to see what singing insects would emerge in the darkness. We were gifted with some good displays by several species, including the first broad-winged tree crickets I have heard singing this year.

The raspberry colored top of the head and bases of the antennae distinguish this species.

While I was attempting to get clear photos of that tree cricket, someone noticed another insect near it. This one arrested our attention. The greater part of an inch long, its broad face and extremely long antennae, its reddish color, and the apparent lack of wings contrasted it with everything we had seen that day. It was tempting to call it a nymph, but I had a hunch that this was a cricket belonging to a wingless group.

Fortunately this odd insect posed long enough for a clear photo.

The next day I went to the BugGuide website, a generally reliable source of insect images, and it and other web references identified this as a Carolina leaf-roller. This is a truly odd cricket, the only member of its family (Gryllacrididae) north of the tropics. The family is mainly a southern hemisphere group, with many of the several hundred species found in Australia. Carolina leaf-rollers spend the day sheltered in a leaf they roll up and glue closed, or sometimes in the inflated pod of a bladdernut bush. At night they emerge to prey on aphids. They are not singing insects, indeed being wingless, but are fascinating creatures nevertheless.

Swamp Cicada Confirmed

by Carl Strang

Two years ago I was positive that I had heard swamp cicadas at Springbrook Prairie Forest Preserve, and posted about it in this blog. The habitat and song were right. However, I had not seen any of them, failed to hear any when I checked the site last year, and doubts developed as I noticed how percussive are some songs of Linne’s cicada, our most common summer species. On Saturday morning I returned to Springbrook for another try (this cicada is mainly a morning singer). I heard a distant cicada that sounded right, and made my way to a pair of small isolated mulberry trees.

They were in a dry location elevated above the stream that was converted from a straight ditch to a proper meandering configuration a few years ago.

I came in too quickly and the cicada flushed, but he simply flew to a new perch higher in the same tree. He resumed singing, and I was able to get a good binoculars view. The swamp cicada, unlike most of our members of genus Tibicen, is physically distinctive. It is largely black, with some green about the head and brilliant white spots on the sides of the abdomen. I was able to confirm the identification, and brought out the camera.

Not the sharpest photo, but sufficient to document the identification.

As singing cicadas often do, he changed his location slightly every few songs.

Here’s a side view. Note that he has lowered his beak.

I was able to get good recordings of the songs, too. I feel confident now that I can identify this species by song. It is based on a pulsing vibrato like that of Linne’s cicada, but is distinctively percussive. Though some individual Linne’s have a hard quality to their vibrations, it is not as sharp, and the sound quality is different. To my ear, the swamp cicada’s song is reminiscent of a rapidly struck tambourine. You can hear an example at the Songs of Insects website.

The significance of this is that the swamp cicada is not supposed to occur this far north in Illinois, though it does so farther east. The swamp cicada joins other species including the broad-winged tree cricket, jumping bush cricket, and round-tipped conehead as singing insects that have extended their range to the north in recent decades. Note: older references give chloromera as the species name for the swamp cicada, but more recent ones have been calling the species Tibicen tibicen.

Horlock Hill

by Carl Strang

Horlock Hill Prairie is regarded as one of the highest quality bits of dry prairie in northern Illinois. It is located right at the start of the Great Western Trail in Les Arends Forest Preserve in Kane County, and I have zipped right past it on my bike many a time without realizing its significance.

The designated natural area itself is small, at 2-3 acres, but I was impressed by the floral diversity.

Adjacent meadows and prairie restoration projects enlarge the effective area in prairie or prairie-like vegetation. In one of these I spotted a small meadow katydid which appeared at first to be a short-winged, but lacked the orange abdomen tip. He allowed me to get some photos, and when I looked at them later I was pleased to see the distinctive cerci of a straight-lanced meadow katydid.

The cerci are the little pincer-like structures at the tip of the abdomen. They are long, straight, abruptly flattened in the tips, and the small, inward-pointing tooth is near the base of each.

I found a female of this species at Mayslake Forest Preserve last year, but this is the first male I have seen. The only congeners I heard around Horlock Hill through the SongFinder were abundant short-winged meadow katydids. It was a cool, cloudy day, however, and the song of the straight-lanced is a steady uninterrupted faint buzz that may have been too faint to hear under those conditions. Certainly the short-wings were slowed quite a bit.

Otherwise the singing insects there were all of common species, except that I heard a couple probable broad-winged tree crickets. All of this points to a return to that site under warmer conditions.

So, Which Is It?

by Carl Strang

Last week on one of the warmer days I was walking through the south savanna at Mayslake when I heard what sounded like a broad-winged tree cricket singing. I had heard some a few weeks earlier, but hadn’t taken the time to find one to photograph, and I thought that here was one last opportunity this season. Eventually I found it, but the insect was no ideal broad-winged.

Broad-winged maybe dark 3b

I was caught without collecting equipment or sound recording equipment, but I got photos before the cricket hopped away. The light wasn’t right, but there did seem to be some color around the head.

Broad-winged maybe dark 1b

It didn’t look like broad-wingeds I’ve seen elsewhere, like the first one at Blackwell a few years ago.

Broad-winged tree cricket 4b

In fact, it looked more like a black-horned or Forbes’s tree cricket, like this one also at Blackwell.

Black-horned or Forbes's male 1c b

The wing width to length ratio falls between the two, but a little closer to that of the broad-wing. I’m leaning toward a black-horned or Forbes’s, despite the contradictory song, habitat and wing proportions, because I have never heard of broad-wings having such dark legs and antennae. Here is another thing to watch out for in future seasons: here at the northern edge of an expanding range, could there be new variants popping up among the broad-winged tree crickets? Alternatively, how often do the songs of black-horned/Forbes’s converge on those of broad-wings?

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