The main focus of my research these days is traveling through the 22 counties of my survey area, seeking the singing insects that live in the Chicago region. I am building on previous years’ work, filling gaps in range maps. The currency I work in thus is county records. There are around 100 species known to have occurred here, and so the maximum total would be 2200 county records. This is not going to be the eventual result, however, because many of the species live only in limited areas within the region. For instance, last week I closed the book on the green-winged cicada.
This distant photo is the best I have so far of a green-winged cicada.
I do not expect to find green-winged cicadas beyond the 10 marked counties.
They occur only in sand soil woodlands within the region. Though other counties have some areas with sand soils, I have searched them and failed to find the species. Their numbers clearly diminish at the periphery of their range. Four of these county records have been from this year.
Other species are widespread, and ultimately I expect to find them in every county. Two early season species now have filled maps as a result of my travels this spring and early summer: Roesel’s katydid, and gladiator meadow katydid.
There is learning involved in the process. Some species which historically have occurred in the area I have not yet found. Others I have found once or twice. At some point I become familiar enough with a species that I know how to find it. Then I seek it out in the appropriate habitat in the counties where I haven’t found it. The sulfur-winged grasshopper is an instructive example. This year I made a push to complete the map for this early-season species. Though I ran out of time before the end of its season, I got close.
Updated map for sulfur-winged grasshopper (open circles represent historical records)
Next year I will check sandy sites in two of the counties in Wisconsin, LaPorte County in Indiana, and Berrien County in Michigan. Though I suspect that sulfur-winged grasshoppers occur in every county, they are very few and hard to find away from sand soils. Though my own county of DuPage is marked, it is a clay soil county and over the many years I have lived here I have encountered fewer than 5 sulfur-wings in DuPage.
A final example is the northern bush katydid. I had heard two of these in the early summer of 2007, in woodlands in my county. I had heard none since. But a few days ago I went back to one of those sites and tried listening at night with the SongFinder, a device which reduces the pitch of sounds. Lo and behold, I discovered that Parson’s Grove at Danada Forest Preserve has a lot of northern bush katydids. I hadn’t realized that it was the deterioration of my hearing with age that had prevented my detecting them. Now I anticipate finding them in every county in the region.
So far this year I have accumulated 47 county records. I expect to end up with more than last year’s 174.
The most fruitful recent singing insects search was at the Kankakee Sands preserve in Kankakee County, which has become one of my favorites for species that affiliate with sand-soil habitats. The June 28 visit yielded 3 county records, two of which were of familiar species, Roesel’s katydid and green-winged cicada.
Grasshoppers were building up their diversity at the site. Sulfur-winged grasshoppers still were going, and the season’s first mottled sand grasshopper also flashed his wings.
This was by far the earliest I have found this sand-soil specialist.
Then in the prairie beyond the savanna I started to hear the zuzz-zuzz-zuzz of stridulating grasshoppers. I had a hard time getting a look at who it might be. Eventually I saw a possible candidate.
This grasshopper has a somewhat slanted face, and color markings reminiscent of stridulating grasshoppers in genus Orphulella.
Study of the photos, however, led to an identification as the meadow purple-striped grasshopper, Hesperotettix viridis, in the non-singing spur-throated grasshopper group. As I waded through the grasses I flushed out a couple really odd grasshoppers that begged to be photographed.
The blade-like antennas, subtle striping pattern, and especially the gangly skinniness of the critter were distinctive.
They reminded me of high school basketball players whose growth spurts have given them impressive height, but whose strength and coordination have some catching up to do. Though I saw and photographed only the minute-winged females, my identification and study convinced me that these were the stridulators. The short-winged toothpick grasshopper is well named, seeming to be constructed of toothpicks. It is a member of the slant-faced stridulating subfamily, and is described as being a frequent singer. The species, also known by the more mundane name of bunchgrass grasshopper (Pseudopomala brachyptera), now is removed from my hypothetical list for my survey region.
In a preliminary way I have begun to look at the question of how wing length affects song production in Roesel’s katydids. This seems pretty esoteric at first glance, but it has personal practical application, as I will explain. Roesel’s katydid is a European import which first appeared in the late 1940’s around Montreal, Quebec. They since have spread to the point that they can be found throughout northern Indiana and Illinois, and at least much of Michigan and Wisconsin. They come in a variety of wing lengths:
Short, as in this female in Kendall County, Illinois…
Intermediate, as in this male recently photographed at St. James Farm…
And long, as in this male at Blackwell Forest Preserve.
Researchers have noted that long-established populations in the European homeland are composed almost entirely of shorter winged, therefore flightless, individuals. The frequent observation of long-winged variations here has fostered the speculation that this has to do with dispersal as Roesel’s katydid expands its North American range. That may be true in the long run, but the edge of that range is far from the Kendall and DuPage County locations of the above individuals, and long-winged ones remain common.
Since I began my study of singing insects in 2006, I have been disappointed to find that each year my ability to hear the buzzing song of male Roesel’s diminishes. Furthermore, on hot days I can hear them fine in the cooler morning hours, but at some point I can no longer hear them. The pitch of their song rises with temperature, until it goes above my audible range. The SongFinder pitch lowering device proves they still are singing (incidentally, the buzz is steady when I hear it unaided, but through the SongFinder it has a superimposed vibrato which becomes more rapid with increasing temperature. This doesn’t happen with other singing insects).
Over the winter the question came to me whether the wing length of the males affects their song. Next year, retirement will allow time to pursue this in more detail, but for now I have an afternoon’s observations that seem to support a difference. I was following trails through north Blackwell’s meadows, occasionally listening with the SongFinder. The temperature was mid-70’s F. Many Roesel’s were singing, but I would not have known this without the device. Then I heard one unaided. I sought it out, and it was long winged. The same was true of two other individuals (the third is the one in the above photo).
Next year I want to make recordings of individuals with different wing lengths, and compare the parameters of their songs. Perhaps the analysis also will give some idea why the pitch-altered song has that vibrato. I want to think, too, about the possibility that there is an evolutionary dynamic going on here. If the song is different among males with different wing lengths, does that matter to females? If so, how? For instance, if long-winged females prefer long-winged males, and short-winged females prefer short-winged males, this could retain genes for long wings in the population for a reason other than dispersal advantage.
The Forest Preserve District of DuPage County’s Centennial Bioblitz started under rain and somewhat cool temperatures last Friday night. We sent off the first plant survey teams and frog monitors, and a small bird team went out, but the rain continued. As the darkness built, it became clear that light stations for insects would get limited results. I gathered the group who had come for one of the public programs, and Purdue University entomologist Jeff Holland explained that the dripping water would explode their hot bulbs. We set up my ultraviolet light, and Jeff led the team into the forest at St. James Farm.
Dr. Holland examines a beetle one of the participants found.
The kids had a great time catching fireflies, and finding insects and other creatures active in the rain.
Classic kid nature fun was had by all.
When we stopped by the light on the way back, we found a few beetles and small moths, but the sheet mainly held a host of mosquitoes.
Amid hundreds of floodwater and other common mosquitoes, there were a few huge ones.
Late into the night, and much of the next day, my focus was on support and organizational work, but I did make two brief field excursions and added a few species to the count on the four preserves of the bioblitz survey.
This green darner showed off its bullseye face paint.
Halloween pennants have been common around the county in the past week.
I recognized the chickweed geometer from my preserve monitoring work at Mayslake.
Roesel’s katydids had begun to sing in the previous week. This mature male has short to medium-length wings.
This coneheaded katydid nymph at the edge of the parking lot meadow was large enough, and its cone the proper shape, to be a sword-bearing rather than round-tipped conehead.
The botany teams no doubt caught this one, but I couldn’t resist photographing these starry Solomon’s plume fruits at Blackwell.
Our rough estimate at the end of the bioblitz was 900 species documented for the four preserves. I will report more detailed numbers when we have them.
On Tuesday of last week I drove north to seek early season singing insects in 5 Wisconsin and northern Illinois counties. I was prepared to camp overnight, but with rain in the forecast for the next day I was happy to complete the run in one day.
My first stop was Middlefork Savanna in Lake County, Illinois.
Spring field crickets were singing, but vegetation still was wet from an overnight rain, and I was lucky to spot this greenstriped grasshopper to give me that county record.
From that point it was rapid-fire site hopping, and I didn’t take many photos.
An exception was this Roesel’s katydid nymph at Wadewitz Nature Camp, a Racine County (Wisconsin) Park.
Wadewitz has extensive grassy meadows, and the biggest surprise of the day was not finding displaying greenstriped grasshoppers in the warm sunny mid-day. Ultimately I was able to find both spring field crickets and greenstripeds in all 5 counties, but several stops were required in some cases.
We are at a point in the season where the spring-singing insects are finishing, and the early summer brings new voices to the chorus. Green-striped grasshoppers seemed to tail off rapidly in their crepitating flights this year. I have heard very few in recent weeks.
The male green-striped grasshopper usually is brown. He’s the one who does the displaying.
The object of his displays usually is green, and a bit bigger than him.
Roesel’s katydids rapidly are increasing the number of buzzes they are contributing to the meadows and prairies.
Note the blur in the wings as this short-winged Roesel’s katydid sings. Some individuals have much longer wings.
Over the weekend I heard first songs from three additional species: Linne’s and dog day cicadas, and the gladiator meadow katydid.
This was one of several gladiators singing beside the Regional Trail in south Blackwell Forest Preserve Saturday evening.
Those Tibicen cicadas, especially, characterize the sound of summer for me.
Each year the Indiana Academy of Sciences selects a site within that state for a bioblitz. This past weekend’s was my third, and it always is a great way to kick off the field season. The location this year was Eagle Marsh, on the western fringe of Fort Wayne.
A large open barn in the center of the site made for a good headquarters.
Support for the visiting scientists and other volunteers was excellent. Here, the morning’s adventures are shared over box lunches on Saturday.
The objective of a bioblitz is to find as many species of organisms as possible in a brief period, usually 24 hours. Scientists who specialize in different taxa lead teams that explore the site. Eagle Marsh is dominated by wetlands, as the name implies. In fact it sits on the boundary between two watersheds, the Great Lakes to the north, and the Mississippi River drainage to the south.
This fence is intended to block Asian carp from reaching the Great Lakes when the rivers flood. It soon will be replaced by a more reliable berm.
The site largely is a restoration project begun in 2005, though some teams found surprising diversity in parts of the preserve. My singing insects team was limited by the early date. We found a grand total of 3 species.
This Roesel’s katydid nymph was one of a small cluster we found on an elevated bank.
This bioblitz invited members of the public to assist those scientists open to such participation. I was delighted to have a team, for a change, and we enjoyed all the organisms we were finding.
Northern leopard frogs were abundant, a sign of how rapidly the wetland is improving in quality.
Peck’s skipper was one of a number of butterfly species we observed.
Jeff Holland’s Purdue University entomology team always provides a highlight with their beetle-drawing lights.
1000 watts of power.
Helpers collect some of the insects that fall to the sheets below.
Here is what they were seeing.
Congratulations to Betsy Yankowiak and the Little River Wetlands Project team for a job well done.
Betsy presented an overview of the area’s geology for interested participants.
On Sunday afternoon, during a bike ride through Fermilab, I heard the first spring field crickets of the year. They had just begun, as there were only 3 of them. This is the third earliest date I have heard them in DuPage County, a little surprising given the late spring, though the deep snow that covered the ground most of the winter certainly provided the nymphs with protection. If a larger population survived, some statistical outliers could be starting up earlier than otherwise would be the case.
Cheating a little here: this is a fall field cricket female, but that species is physically identical to its spring sibling species.
Apart from such uncommonly encountered critters as sulphur-winged grasshoppers and spring trigs, the next common singing insects to mature should be the predaceous katydids (Roesel’s katydid and the protean shieldback), and gladiator meadow katydids. By then I hope that the spring field crickets will have built numbers to the point where I can finish my county survey of their distribution.
The start of the singing insect season still is a couple months away, but among the early species will be the three katydids I am featuring today. They are relatively hardy, hatching very early in the spring and developing quickly. Two of them, Roesel’s katydid and the protean shieldback, are known as predaceous katydids, and their dietary focus on animals is what allows them to get going so early. The gladiator meadow katydid is the earliest of its species group to hatch, and so the earliest to begin singing. The meadow katydids are generalists, and the gladiator probably has a greater proportion of animal foods in its diet than the others. Roesel’s katydid is a European species, introduced in the Montreal area and spreading south, east and west from there.
Roesel’s is the only katydid in the Chicago area with a color pattern anything like this.
Its song is a long, fast, constant buzz:
I am at an age where I have a little more difficulty hearing this one each year. The pitch rises with temperature, and on a hot mid-day I now need the SongFinder pitch-altering device to hear individuals that are audible in the morning and late afternoon.
The protean shieldback, like Roesel’s katydid, is a species of the meadows, but also is common in brushy areas and open woodlands.
Protean shieldback female. This is a relatively heavy-bodied katydid
Its song is an extended buzz, but has much more of a slower, rattling quality than Roesel’s song.
It is not as loud as it may seem from the recording, but is not really difficult to hear. The protean shieldback begins singing in mid- to late afternoon, and continues into the night.
The gladiator meadow katydid is similar in appearance to other large meadow katydids.
This photo shows why the meadow katydids once were known as “long-horned grasshoppers.”
The gladiator meadow katydid’s variation on the generalized tick-and-buzz meadow katydid song pattern de-emphasizes the tick portion. I often don’t notice ticks at all, though they may be softly produced more often than I suspect, as in the following recording:
The buzz is similar in quality to the protean shieldback’s song, but it is shorter in length, rhythmically produced, and the volume rises at the end.
In order for us to understand insects well enough to know which ones need the most attention in conservation, there are some pieces of information we need: how abundant they are, how broad or narrow their habitat needs, their reproductive potential, and their dispersal ability. The first two items are readily obtained in the course of a regional survey such as I am conducting for singing insects in northeast Illinois and counties in neighboring states. Reproductive potential has been studied to some extent and can be found in the literature for some species. Dispersal ability is a critical point that is not well studied as far as I can tell, and so it is good to take advantage of observations that reveal which species spread easily, and which ones do not.
Over the past two weeks I spent much time in the St. Joseph Hospital in Mishawaka, Indiana, where the medical professionals saved my mother’s life.
The hospital was built 3-4 years ago, and is surrounded by extensive areas planted mainly in native prairie plants.
Occasionally I took walks along the paths, or made observations while arriving or departing. The species present in the plantings can be regarded as ones with high dispersal ability. These included field crickets (I cannot be sure which, as this was the cusp between the spring and fall field cricket seasons), striped and Allard’s ground crickets, Carolina grasshoppers, Roesel’s katydids, and a sword-bearing conehead. All of these are regionally abundant, and fairly broad in their habitat (dry to mesic mixes of grasses and forbs). Three have good flying ability (in the case of Roesel’s, there are long-winged individuals as well as medium and short-winged ones). Field crickets and the ground crickets can take advantage of their regional abundance and tendency to hop and walk over land. One limitation here is that I was only able to make observations over a brief portion of the season.
If I had to point to the weediest singing insect in our region, I’d have to say it’s the striped ground cricket, which is the quickest to appear in a new site.