The Tiny Ones

by Carl Strang

One of my goals this year was to achieve some clarity with two of the tiniest singing insects in the Chicago region. The variegated ground cricket (Neonemobius variegatus) and Cuban ground cricket (N. cubensis) are only a quarter to a third of an inch long. They are so unobtrusive, with their low-volume trills and hidden haunts, that you have to listen for them even to know they are around. Both species have rapid trills with crescendo starts, and unless you have perfect pitch and better hearing than me, telling their songs apart means working from sound recordings and getting technical.

Variegated ground cricket

Cuban ground cricket

My accumulated recordings of Neonemobius songs fall into two clusters, demarcated by a space that has remained remarkably consistent.

The dots in this graph each represent a recording of a Neonemobius cricket song, analyzed in the computer. The pulses represent the speed at which the cricket rubs his wings together to produce the song, and the frequency is the highness or lowness of the song’s pitch. Both measures increase with temperature. Note that variegated ground cricket songs fall into the upper left portion of the graph, Cuban ground cricket songs lower right. Dashed lines are my eyeball estimates of the space between the two clusters of points.

Variegated ground crickets vibrate their wings more slowly than Cuban ground crickets, yet have higher-pitched songs at a given temperature. This was the tentative conclusion I had drawn, but I needed some validation, and got it in October.

Here I have to back up a bit. I had found variegated ground crickets in the Chicago region, and would not have considered the possibility of Cuban ground crickets without the work of Lisa Rainsong. Cuban ground crickets had been known as a southern species until Lisa found them to be abundant in Cleveland. Her discovery alerted me to the possibility that they also might have reached the Chicago region. That possibility was realized when I found Cuban ground crickets in Gar Creek Forest Preserve in Kankakee County, Illinois. A captive Gar Creek Cuban ground cricket anchored the right-hand portion of the graph (yellow dots, yellow line).

A few observations of variegated ground crickets in previous years fell into the left-hand cluster, but I needed more. This year a captive variegated ground cricket from Gar Creek, which has both species, provided a series of recordings at various temperatures which fell as expected (red dots, red line).

Early in October I visited Lisa and her partner Wendy Partridge, and they showed me an area where Cuban ground crickets are abundant.

This meadow in the North Chagrin Reservation, a Cleveland Metroparks site, is packed with Cuban ground crickets. Lisa and Wendy check out tree crickets down the trail.

My recordings of two individuals at that site fit nicely into the previously established Cuban ground cricket cluster (green dots).

The final touch for 2018 came on October 18. I had 3 recordings, from 2006-2018, from north Blackwell Forest Preserve in DuPage County, all of which fit into the Cuban ground cricket cluster. Despite a few frosty nights, Neonemobius crickets had survived and were singing. I succeeded in flushing out one of these, and he was indeed a Cuban ground cricket. I regard this as a final validation of the graph. Now I need to go back to most of the 22 counties of the Chicago region in future years, and discover where each of these two species occurs.

Revised distribution of variegated ground crickets in the Chicago region, based mainly on analysis of sound recordings.

Revised distribution of Cuban ground crickets. One or both of the two species occur in every county, but I have not yet made sound recordings everywhere I heard Neonemobius crickets singing.

This story is an excellent example of hidden surprises that are waiting for researchers to uncover.

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More Range Jumps

by Carl Strang

One recurring theme of my singing insects survey work is the northward extension of species’ ranges. Late in this year’s field season, three more species turned up significantly north of where I had found them before. One of these discoveries was made by Nancy Collins, who found broad-winged tree crickets (Oecanthus latipennis) half a county north of the Illinois border in Kenosha County, Wisconsin, more than 30 miles beyond where I had found them before.

Broad-winged tree cricket

I had not found this species in the northernmost row of Illinois counties, but I hadn’t looked for them there in recent years. Inspired by Nancy’s discovery, I did some searching and found them in Lake County at Chain O’Lakes State Park. Next year I want to seek them in McHenry County, Illinois, and Walworth and Racine Counties, Wisconsin (unless, of course, Nancy finds them there first).

The handsome trig (Phyllopalpus pulchellus) surprised me last year by turning up in sites across the southern half of my home county of DuPage in Illinois.

Handsome trig

I set the modest goal this year of seeking them in Kane County, just west of DuPage. Recently I succeeded in that, finding a group of them a little west of where I had found them in DuPage, but that was not surprising. What bowled me over was finding a small population of them in the East Main Street Prairie park in Cary. This is 22 miles, more than half a county, farther north, McHenry County being just north of Kane. This continued the pattern of handsome trigs popping up in separate scattered locations, because I tried to find them in northern Kane County and western Lake County, areas not far from Cary, without success.

The third species is one I have written about several times before, because it is spreading quickly, and soon becomes abundant in areas behind the front of its expansion. This is the jumping bush cricket (Orocharis saltator).

Jumping bush cricket

Last year I encountered a small population of jumping bush crickets in Wauconda, Lake County, Illinois. This was a good 12 miles north of where I had found them before. I still suspect that these were inadvertently transported there by people, and I wondered if they could reproduce successfully. Indeed there were even more males singing in that spot this year. The surprise was finding them in towns all along the west bank of the Fox River, nearly to the northern border of Kane County. This is a few miles south of Wauconda’s latitude, but a search of the southeastern corner of McHenry County, between the two locations, failed to turn them up. To be continued in future years…

Berrien Explorations

by Carl Strang

The end of August found me in Berrien County, Michigan. The first stop was the Butternut Creek Fen preserve, where I met tree cricket specialist Nancy Collins. We spent an afternoon and evening seeking tamarack tree crickets, which had been found there years ago. There are abundant tamarack trees, but we were puzzled by the crickets’ no-show. None sang, and hours of arm-tiring sweeping of foliage with long-handled nets, as well as visual scanning of branches, were fruitless. We found other species, though, and provided the site owners with a list of what we observed.

When Nancy found this fork-tailed bush katydid I was hopeful that it would prove to be a rarer cousin, the treetop bush katydid, but no dice.

Oblong-winged katydids also are at the site. My new white chamber setup worked well in the back of the car.

The next day I wandered in Berrien, St. Joseph and LaPorte Counties. The best find was a new site for me, Glassman Park in Berrien County. I bypassed some nice-looking forest, then was captured by a mundane looking grassy area adjacent to the I-94 right-of-way. It proved to have some interesting grasshoppers.

Most of these proved to be pasture grasshoppers, only the second population of this locally distributed species I have found in my study region.

A second species had a much different look.

The handsome grasshopper has an even more slant-faced profile.

With a color pattern like this, the handsome grasshopper is well named.

The day was my final in Berrien County for 2018, but there is more singing insect work to be done there in coming years. That is bound to include at least one more listening stop at Butternut Creek.

 

Hitchhiker Surprise

by Carl Strang

In the last week of August I pushed to close the book on melodious ground crickets (Eunemobius melodius) in the Chicago region. I found that a marginal 2017 sound recording in DuPage County, Illinois, in fact was a Say’s trig, failed to find melodious ground crickets in Kane and Kendall Counties, and found them at a site in St. Joseph County, Indiana. This left Jasper County as the remaining candidate county where I had not found the species. I had found them in floodplain forests in all the other counties bordering the Kankakee River, but there are few places in Jasper County where the river intersects public roads. Otherwise the only possibility was floodplain wetlands in the Jasper-Pulaski Fish and Wildlife Area, and they are not there. On August 26 I checked the places along the river, and though I could see likely habitats from the road, all were on posted private property. Here is the final map:

Map of the Chicago region, black dots indicating the counties where I have found melodious ground crickets. They probably also occur in Jasper County on private property.

I was happy to close the book on melodious ground crickets, but the highlight of the day was a hitchhiker. As I pulled away from a road that dead-ended at an extension of the river, I noticed a cricket on my windshield that I did not recognize. I stopped the car and caught the cricket.

The brown wings with yellow borders were vaguely familiar.

After returning home I was inspired to slap together a makeshift white chamber, inspired by Wil Hershberger’s work, in order to take portrait photos of the stranger.

I thought I had seen photos of crickets like this, and a little research turned up the identification: restless bush cricket (Hapithus agitator). The Kankakee River fringe in Jasper County is now the second-farthest-north location where the species has been found, according to the Singing Insects of North America website (a site in Massachusetts is the northernmost). I will add a page to my singing insects guide for the species, but there’s an asterisk. Restless bush crickets are widespread in the eastern U.S., but they are known to sing only in Texas and Florida.

Three in One Day

by Carl Strang

This is the 13th year of my singing insects study, but there remain several species that historically were known in the Chicago region but that I have not yet found. Each year I have found one or two new ones. On Saturday, August 18, I found three.

This was down in Will County, Illinois. I had spotted a possible good site for singing grasshoppers within the Des Plaines Conservation Area late last year, and I made it my first stop. The first species I found were relatively common until I reached a portion of dolomite prairie where the bedrock was at the surface. Bare rock was edged by patches of grasses in poor, thin bits of soil. Among the grasses were tiny slant-faced grasshoppers, and I took photos of several of them.

They were colorful and variable, some green like this one, some gray, some brown with tan backs.

Here is one of the brown ones.

They proved to be pasture grasshoppers (Orphulella speciosa), smaller relatives of another species I had found in the Gensburg Prairie in Cook County, the spotted-wing grasshopper (O. pelidna). Both are described as locally distributed, and that clearly has been the case in my experience.

Out on the open bedrock I began seeing slightly larger grasshoppers that appeared to belong to another singing subfamily, the band-winged grasshoppers. Catching one was a challenge, but eventually I got good looks at a male and a female.

The male’s profile shows a head that protrudes above the thorax, a double-humped pronotal ridge, and antennas that are thread-like rather than flat, barely longer than the head. They were even shorter in the female I examined.

These were Kiowa rangeland grasshoppers (Trachyrhachys kiowa), a western species whose range reaches into the Chicago region. There are two variants, one with transparent wing bases.

The male proved to be of the pale yellow wing base variant.

This new-species haul was exciting, but I wasn’t done. I was driving to nearby Wilmington for dinner when I heard a sound I had begun to believe I would never hear in the region:

There was a continuous underlying drone, with an overlay of short monotone buzzes. A Walker’s cicada (Neotibicen pronotalis)! I pulled over to the edge of the road and approached the catalpa tree where the insect was perched. As I made the above recording I noticed a movement out of the corner of my eye. A sheriff’s officer had pulled his car beside me (his car motor covered the cicada’s drone, and you may have noticed a little blurp from his radio in the recording). He politely waited for me to finish, then explained that there had been troubles in that area. I admitted that my behavior might seem suspicious, but he accepted my explanation.

There are only a dozen or so species of singing insects that I might still find in the region. I doubt that I will again find as many as three in a single day.

Less Confused

by Carl Strang

An emerging theme of my field season this year is defining range boundaries of the singing insects I am studying. When there is a boundary within my 22-county study area, usually the population density thins out toward the edge. That has me looking critically at some of my past observations. A case in point is the confused ground cricket (Eunemobius confusus).

Confused ground cricket. These are little guys, a quarter of an inch long.

Looking at past records, I found that only two were north of the midpoints of Kane, DuPage and Cook Counties in Illinois. There was a single individual in the Lyons Prairie and Marsh area, legally within Lake County, Illinois, though managed by the McHenry County Conservation District. I had noted a small group of the crickets in the New Munster Wildlife Area in Kenosha County, Wisconsin. Now several years on without other records for those counties, I felt the need for a double check. I visited both sites and found no confused ground crickets. I did, however, hear other singing insects that I now believe fooled me.

Here is a recording of a confused ground cricket. This guy was singing in cool temperatures, and so was slowed somewhat:

Usually the song would be faster, with trills or chirps about a second long, alternating with equal-duration spaces within which the cricket produces stuttering sounds. The Lake County and Kenosha County observations both were made well into long days in the field, and my fatigue along with relative inexperience years ago, led me to mistakes. I now believe that the Lake County observation in fact was a Say’s trig, producing an uncommon alternative song composed of brief trills with the same timing as a confused ground cricket. Here is an example of that song:

You may notice there are occasional stutters between the trills. On my return visit to the New Munster site, I did not hear any confused ground crickets, but I noticed that there were a lot of black-legged meadow katydids singing in dry habitats, unusual and unexpected in that species. Furthermore, in the heat they were singing so fast that their buzzes were about a second long, with the ticks compressed in such a way that they resembled a confused ground cricket’s stutters. Here is a black-leg recording with similar timing:

These conclusions support my practice of making lists of the species I hear on each visit to each site. That makes the oddities stand out, helping me to correct errors like the ones I have described here. I now can close the book on confused ground crickets, with the final map:

Black dots indicate counties where I have found confused ground crickets. The red stars mark locations of the northernmost observations within Kane, DuPage, Cook and Berrien Counties.

Cicadas East, Cicadas West

by Carl Strang

Today’s puzzle is the odd range boundaries of two cicada species that occur in the 22-county area I define as the Chicago region.

The scissor-grinder cicada (Neotibicen pruinosa) is one of the four most abundant annually-appearing cicadas in northeastern Illinois.

Scissor-grinder cicada

Though individuals may sing occasionally from mid-morning to dark, their ee-oo-ee-oo-ee songs especially dominate the wild soundscape at dusk in mid- to late summer. In the following recording, the cicada is introduced and ushered out by a nearby striped ground cricket.

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A recent review of North American cicadas (Sanborn and Phillips 2013, Diversity 5: 166-239) shows what appears to be a gap in the species’ distribution in north central Indiana. I was inclined to regard this as simply indicating a lack of sampling in that area, but this year I pushed to complete my own map for scissor-grinders. Here is the result:

Black dots indicate counties where I have observed scissor-grinder cicadas.

The numbers of scissor-grinders thin out dramatically in the eastern and northern counties of the region. I cannot find them at all in Walworth, Berrien, St. Joseph or Fulton Counties. They barely reach the southwest corner of Marshall County. Sanborn and Phillips show them picking up again farther east, but only one record each for Wisconsin and Michigan, in both cases outside my region.

There is no obvious explanation for the Indiana gap. It does not correspond to soil type, as scissor-grinders can be found in both sand and clay soil areas, and are absent from areas of both.

Swamp cicadas (N. tibicen) have a distribution mainly south and east of the Chicago region, and Sanborn and Phillips (2013) do not map them into the Illinois or Wisconsin portions of my region. My work extends that range a little, but they are scattered individuals in Illinois, with only one Kane County and one Kankakee County site.

Swamp cicada

Black dots indicate counties where I have observed swamp cicadas. Red stars show locations of the northernmost records.

Their song is a percussive vibrato. Here is a recording from southern Indiana in which several individuals provide overlapping songs:

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They occur mainly in the Kankakee and DuPage River areas in Illinois. In the southeastern portion of the region, a few can be found along the Tippecanoe River in Fulton County, but they apparently drop out before that river reaches Pulaski County, which also is well south of the Kankakee River drainage. The swamp cicada’s range boundary is a western one, but explaining it is just as difficult as in the scissor-grinder. St. Joseph County seems to be the center of abundance in the region, with Potato Creek State Park having an especially high density.

The practice of science is largely about questions, and these newly discovered odd range boundaries provide good ones for these two cicada species.

Closing the Book on Green-winged Cicadas

by Carl Strang

The green-winged cicada (Diceroprocta vitripennis) provides a favorite example of why I need to include 22 counties in my survey of Chicago-region singing insects. I checked a final two locations recently, and am satisfied that I have a good sense of where this species occurs.

Black dots indicate counties where green-winged cicadas can be found.

The most important habitat feature appears to be sandy soil. Cicadas spend most of their lives underground, so it is not surprising that soil texture can influence their distribution. The mapped area contains two sandy regions: the dunes edge of Lake Michigan in Indiana and Michigan, and the Kankakee River corridor. The cicadas do not, however, extend throughout those soil areas. They thin out quickly in western Starke and Pulaski Counties, Indiana, and do not reach into the sand soil portions of St. Joseph and Marshall Counties.

Green-winged cicadas had an important lesson for me this year. Previously I had thought of them as a woodland species, having observed them singing in trees, especially in black oak savannas and woodlands. Then I came to this spot in Newton County, Indiana:

A single large cottonwood and two smaller trees towered above clusters of shrubs.

I was surprised to step out of the car, expecting to focus on sand-soil grasshoppers, and hear green-winged cicadas singing. As I approached them I found that they were singing, not from the big trees, but from plants no taller than me, winged sumacs and a small black oak.

This discovery provided a welcome opportunity to photograph live green-winged cicadas.

They were very alert, and required a glacially slow stalk.

Feel free to wave back. No one is watching.

I also found a site in Jasper County where the cicadas were singing from shrubs. They can be fairly loud at close range, but they are small, with bodies not much more than an inch long, so the song quickly attenuates over distance. It seems to carry better when the singing perch is in a tree. The song is a distinctive pulsing rasp:

These early season cicadas sing mornings to mid-afternoons, and largely are done by the end of July.

Southern Lessons

by Carl Strang

This year’s chapter in the series of annual bioblitzes organized by the Indiana Academy of Sciences took place at Eagle Creek Park in northern Indianapolis on June 2-3. This is early enough in the season that there were few singing insects for me to find, but I was able to gain valuable experience with two southern species that occur or have occurred in the Chicago region.

The first of these is the spring trig.

Female spring trig at Eagle Creek.

This species of tiny cricket first was described in 2014. That is surprising, given its abundance in southern Indiana and its extensive range beyond the state. It proved to be common in a range of habitats at Eagle Creek Park, from woodland edges to grassy meadows.

Spring trigs appear plain-faced to the eye, but bright light and magnification reveal a pattern of fine dark lines.

I learned more about the spring trig’s habitat, and found that I can hear them easily while driving at speeds of 30mph or less. This allowed me to get clarity on the species in the Chicago region. Driving in the southernmost counties, I found widely scattered small colonies in Fulton and Jasper counties, at road edges where wider bands of herbaceous plants were backed by woodlands. In the future I expect to find them in southern Pulaski and Newton counties, too, but not north of there.

Eagle Creek Park also has a large population of northern wood crickets.

The northern wood cricket is a forest species that is smaller and blacker than the spring field cricket, which could be heard chirping in the park’s meadow areas.

The spring field cricket is a few millimeters longer, typically has bronzy wings, and has a proportionately broader head and thorax.

Recordings I made during the bioblitz, and at home with a captive male, have provided further clarity on northern wood cricket song characteristics. Their chirps may never have 4 pulses (commonly 2 or 3), and almost never rise above 5 kHz in pitch, where spring field crickets often have 4-pulse chirps, and seldom drop below 5 kHz. Habitat also helps separate the two. I dug deeper into the literature, and learned more about historical records of the species in two Chicago region counties. Those observations were made in 1902, and I went to the sites in the weeks after the bioblitz. Northern wood crickets no longer occur there. I believe the records are correct, but that the crickets have gone extinct in those places. Northern wood crickets are reported to be sensitive to forest fragmentation, perhaps especially so in the northern fringe of their range, and such fragmentation clearly took place where they once were found in Lake and Marshall counties. I will continue to check the region’s larger surviving forest blocks, but it seems likely that the species no longer occurs in northern Indiana.

Incidentally, the other expected early-season singing insect, the green-striped grasshopper, lives in Eagle Creek Park’s meadows and prairie areas.

Next year’s bioblitz is expected to take place in one of my counties, and I am looking forward to the experience.

 

A Good Burn

by Carl Strang

The Forest Preserve District of DuPage County has invested a welcome amount of effort in restoring the forest at St. James Farm, where I am volunteer steward. Early this spring a large group of trained staff came in and conducted a successful burn of accumulated leaf litter in the main part of the forest. The point of the burn is to kill or at least weaken invasive plants such as garlic mustard and barberry.

The contrast between the unburned trail and the burn area reveals the intensity of the burn.

The burn coverage was about as complete as one could expect.

No burn is complete, however. Some forest floor invertebrate species will need a few years to recover, but there will be plenty surviving in small spots missed by the fire, as well as surrounding areas not included in the burn.

A smaller burn on an earlier date in the area we are clearing of buckthorn was not as complete, because the leaf litter accumulation was relatively shallow and spotty.

I didn’t take any photos of the main burn as it was taking place because I was busy. Our forests historically burned very infrequently, and some of the plants cannot be assumed to be as fire-adapted as the ones characteristic of savannas and woodlands. In particular I was concerned that blackhaws (Viburnum prunifolium), the dominant shrub layer species, might be harmed. So, I worked ahead of the flames, frantically raking dead leaves away from the bases of as many blackhaws as I could reach in the two hours that I had. I did not have time to cover the entire forest, so there were some areas where the flames reached the bases of blackhaw shrubs.

Some blackhaws were heavily scorched.

Other blackhaws were lightly scorched.

Blackhaws I cleared by raking away the leaf litter were unscorched.

In subsequent weeks the forest leafed out, and the blackhaws bloomed.

Blackhaw flower cluster

I spent part of an afternoon assessing scorched vs. unscorched blackhaws. The scorched ones nearly all had plenty of leaves, though a few were killed. Most scorched plants had some flowers, though almost all were limited to 1-5 clusters.

Unscorched blackhaws had abundant flower clusters.

A little less than two-thirds of the scorched shrubs flowered at all, and again, those that did had few. Nine-tenths of the raked blackhaws bloomed, for the most part with many more flower clusters. Sample sizes were large enough to support a strong statistically significant difference. I will continue to watch this, as I am concerned that the scorched plants may have been partly girdled by the flames. I will be recommending that other forest stewards take measures to work with the fire crews and protect the native shrub layer of our woodlands by raking away fuel from shrub bases.

In the meantime, the part of the forest that we have been clearing of buckthorn and other invasive shrubs is showing first fruits of our efforts.

Even in this first year, our treatment area showed an encouraging growth of spring ephemeral herbaceous plants.

One long-term goal will be to promote blackhaw and other native species, so as to restore the shrub layer in the area we have cleared.

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