Periodical Cicada Plans

May 1, 2024 at 6:56 am (singing insects)
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by Carl Strang

Later this month, periodical cicada Brood XIII will begin to emerge in northern Illinois and parts of adjacent states. From mid-May to mid-July my research priority will be to gather observations that will help me fill out the story of these amazing insects in the region.

[There are two species of periodical cicadas in the region, both emerging together. Linnaeus’s 17-year cicada (Magicicada septendecim) is on the left, Cassin’s 17-year cicada (M. cassinii) on the right.]

During the previous emergence in 2007, I focused on DuPage County. I found that the cicadas were concentrated in the eastern part of the county, where urban forests, created mainly along commuter railways, allowed cicada populations to expand beyond the historically forested areas. Cicadas generally were absent from western DuPage, where the forests had been cut down for agriculture.

[Map of DuPage County, summarizing past periodical cicada observations. Pink shaded areas mark where the major emergence occurred in 2007. Brightly colored dots mark places where cicadas emerged in 2020. Black dots show where wave choruses appeared in 2023.]

One goal this year will be to repeat the DuPage survey, to see how much (if at all) the major emergence areas have expanded a generation later. I also will be interested to see if additional new areas might have been established by dispersing gravid females.

A remarkable side story has been the repeated appearance of numbers of periodical cicadas four years ahead of the main emergences. This first was reported in 1969, and in 2000 I found that the cicadas reproduced in sufficient numbers that they have established a separate, independently reproducing parallel population in part of the Brood XIII area.

[Distribution of periodical cicada locations in 2020. In this and the previous map, red dots show areas of the highest population densities, where the cicadas reproduced in sufficient numbers to carry into another generation.]

There also were a few tiny areas, each less than a city block in size, where many cicadas emerged last year (indicated by black dots on the topmost map). These did not, however, successfully reproduce. I will return to the high emergence areas this year, to see if they also have strong numbers four years later. This is to test the possibility that the early emergences are the result of overcrowding underground. Such a scenario was predicted by researchers decades ago, and if so, a strong emergence is expected in those same areas this year. A lack of cicadas in those areas would support an alternative hypothesis, that climate change may be responsible.

I also want to get a sense of the extent of Brood XIII in southeastern Wisconsin, northwestern Indiana, and southwestern Michigan. Historical records show that the adjacent Brood X occurred in every Indiana county, but that there was an extension of Brood XIII along the northern fringes of the northwesternmost counties. In 2021 I found three surviving Brood X populations in northwest Indiana, all south of the Valparaiso Moraine.

[Locations of Brood X populations in 2021. The blue line marks the crest of the Valparaiso Moraine.]

I suspect that the Grand Kankakee Marsh, which was bounded on its north edge by the Valparaiso Moraine, historically was a barricade dividing Brood X from Brood XIII, and I hope to get some confirming observations this year.

Finally, I need to check two locations where a third periodical cicada species reportedly was found in Cook County in the past. These were based on museum specimens, however, and the physical characteristics of these species are variable enough that they need to be documented behaviorally with song recordings.

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Southern Mole Cricket

December 12, 2023 at 7:29 am (singing insects)
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by Carl Strang

In late November I traveled to eastern North Carolina to visit my brother and his wife for Thanksgiving. They live in a community that surrounds a golf course, and the course abuts their back yard. Rain fell for a day after I arrived, and after it stopped, I could hear crickets chirping out on the golf course.

 I made a recording:

These crickets were living beneath the close-mowed turf.

The songs resembled those of northern mole crickets (Neocurtilla hexadacyla), a familiar species in the Chicago region, but were noticeably higher pitched, 1.9 kHz compared to the northern mole cricket’s 1.7. Temperature plays a role here, though, as the recording was made at 17.5 degrees Celsius rather than the standard of 25C for the northern species’ measurement. At 25C the golf course crickets’ songs would be higher still. A review of possibilities in the Singing Insects of North America website pointed to the northern mole cricket and the southern mole cricket (Neoscapteriscus borellii). The latter’s calling song typically is described as a continuous trill at 2.7 kHz, but it also can produce a series of chirps, like those of the northern species but higher pitched.

Here is a recording of a northern mole cricket for comparison, clearly lower pitched despite a warmer 21C temperature:

These North Carolina crickets were singing in a lawn on a hill. Northern mole crickets live in marshes. Southern mole crickets also occur in wetlands, but their habitat range extends to moist lawns. Between the habitat and the higher-pitched songs, I concluded that the golf course dwellers are southern mole crickets.

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Lake Huron Grasshopper

November 16, 2023 at 7:10 am (singing insects)
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by Carl Strang

In mid-September, as the singing insect season was winding down, I was invited to present a paper at the joint meeting of the Michigan and Wisconsin Entomological Societies at Ludington, Michigan, on the Lake Michigan shore of the lower peninsula. On one of the field trips at nearby Ludington State Park, I saw a band-winged grasshopper I didn’t recognize. I was able to catch and photograph a male, and got a shot of a female on the sand nearby.

The male was strongly marked while being well camouflaged. The female was larger and less contrastingly marked, as often is the case with the band-winged group:

The male’s hind wings were yellow in the base:

My practice is to get a complete series of photos when I find an unfamiliar species, and it was well that I caught the inside markings of the hind femur:

As you can see, the basal half is entirely black. This allowed me to secure the identification of Lake Huron grasshopper (Trimerotropis huroniana). This is a more northern congener of the seaside grasshopper (T. maritima), which is common in my region on the beaches around the southern end of Lake Michigan. Though I could have collected the grasshopper, my practice is to rely on photos. I was glad to have released it, as some consider the Lake Huron grasshopper to be a threatened species.

This was a fortuitous encounter, as it provided a preview of things to come. I have practically finished my survey of the singing insects in 22 counties from SE Wisconsin around to Berrien County, Michigan. Next year, after the early season focus on Brood XIII of the periodical cicadas in my region, I will begin seeking experiences with new species farther north in Wisconsin and Michigan, and farther south in Illinois and Indiana.

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Small Meadow Katydid Songs

November 3, 2023 at 6:41 am (singing insects)
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by Carl Strang

As children, we can hear all the singing insects. As we age, though, we gradually lose our ability to hear the higher-pitched ones. When I began to study them in 2006, I already was unable to hear any of the small meadow katydids (genus Conocephalus) in the field. I acquired a device called the SongFinder, which lowers the pitch of songs by cutting their frequency to half, one-third, or one-fourth.

A few years ago, I learned that this device no longer is made, and sought a backup. I ended up with a bat detector.

This one, called the Walkabout, can be set to the range of the higher-pitched singing insects (most bat detectors are limited to frequencies above that range). It has the further advantages of having a speaker instead of headphones, a visual display of the sounds it picks up, and can make recordings. Furthermore, unlike the limited directionality of the SongFinder, its microphone cone attachment allows the user to zero in on a single singing insect for a visual identification.

This year I made better use of both devices, playing with settings and making recordings to improve my ability to find Conocephalus katydids and identify them by their songs, without having to see them. In the following review of species, you may well be able to hear the recordings (made with the Walkabout, with one exception), either because you are in a quiet setting without the competing sounds that overwhelm in the field, or because the recordings are somewhat pitch-reduced.

The most common of these critters in the Chicago region is the short-winged meadow katydid (C. brevipennis). These occur in grasses in a wide range of habitats.

Its song consists of usually 1-3 evenly spaced ticks followed by a short buzz:

The next most common species, which occurs in wet to mesic grasses, is the slender meadow katydid (C. fasciatus).

Here, the ticks are more irregularly spaced and usually more numerous, the whole impression much less metronomic than in the short-winged:

This year I became better acquainted with the black-sided meadow katydid (C. nigropleurum).

One of our more beautiful singing insects, the black-sided is limited to wet areas with some coarser herbaceous vegetation or woody stems. Its song is a continuous series of snare-drum-like rapid ticks (this recording I made with my Marantz digital recorder and a Sennheiser shotgun mike, and includes a common true katydid singing nearby):

The shape of these ticks is distinctive when viewed in a sonograph. This image is one second’s worth:

Another, less commonly encountered wetland species is the long-tailed meadow katydid (C. attenuatus), which can be all brown as in the photo, but also can have bright green legs.

It also has a continuous song that is more like a buzz, the pulses coming more rapidly:

The sonograph shows that the pulses are regular and identical, in this image 0.2 second’s worth:

The straight-lanced meadow katydid (C. strictus) lives in sparser grassy vegetation on poor, dry soils.

Its song resembles that of the long-tailed, but their habitats are distinct.

Also, the volume increases and decreases. This 0.2-second sample shows a decrease:

There are two other Conocephalus species in the region, the woodland meadow katydid (C. nemoralis) and the prairie meadow katydid (C. saltans). The former has a song consisting of rapid-fire brief buzzes, some of which are separated by drumrolls of ticks. The latter produces a continuous series of even briefer buzzes, so short they are almost tick-like. I need better recordings of both, and hope to get them next year.

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Marsh Coneheads Illinois

October 26, 2023 at 6:47 am (singing insects)
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by Carl Strang

One of the targets in my plan for this year’s singing insects survey was an area of the Des Plaines Conservation Area in Will County, Illinois, where I hoped to confirm the presence of marsh coneheads (Neoconocephalus palustris). I had found them in marshes of the Indiana dunes area and in Fulton County south of there, but in Illinois they had been documented only in the southernmost part of the state.

A photo posted in iNaturalist last year appeared to be of a marsh conehead. It was accompanied by the claim that this was a slender conehead (N. lyristes), which is historically known from northeast Illinois but which I have been unable to find in the present day. The photo showed a configuration of the insect’s pronotum which ruled out lyristes but was consistent with palustris. Later the photo was withdrawn, but I had noted its location and went there on August 12. Coneheads began singing at dusk in the marsh vegetation, which is expected for palustris but not for lyristes, which reportedly begins to sing in the afternoon. There were enough individuals singing that I was frustrated in my attempt to zero in on one. I returned a few nights later and this time spotted several coneheads in both green and brown body colors. I caught one for photos.

This green male shows the pronotum shape and head-cone profile of a marsh conehead. In lyristes the cone would be longer, and there would be a sharp right-angle bend in the posterior edge of the pronotum.

The underside of this individual’s cone is green. I saw a brown katydid with a darker, more gray color there. That appears in some of the Indiana dunes coneheads, too, but is not the black that would appear on a slender conehead, which also would have a more elongate cone.

At my age I need my electronic devices to hear these coneheads on warmer nights, which was one reason why I failed to find them on the first visit. The cooler second evening helped. While seeking them with my devices I also was hearing one of the less common wetland meadow katydids, and I took some time to catch one for identification. Stripe-faced meadow katydids (Orchelimum concinnum) occur elsewhere in the Des Plaines Conservation Area, and dusky-faced meadow katydids (O. campestre) sing their similar songs in marshes at the adjacent Midewin National Tallgrass Prairie.

These proved to be campestre, which makes sense because this was more of a marsh, where the concinnum were in wet areas of dolomite prairie.

All of this made for one of the most satisfying moments in this year’s fieldwork.

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Ghost Hoppers

August 3, 2023 at 6:44 am (singing insects)
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by Carl Strang

Early this year I returned to the Seidner Dune and Swale Nature Preserve in Lake County, Indiana, a property of the Shirley Heinze Land Trust. I first visited this beautiful site late in the season last year, and was especially pleased to find a strong population of dusky-faced meadow katydids (Orchelimum campestre) in the wetlands along the Grand Calumet River.

Overview of the wetlands at Seidner. In the foreground are bare patches of sandy gravel.

I knew I would need to return this year, because there are areas with little bluestem grass and bare sandy soils where I might find populations of a couple of the region’s rarest grasshoppers. I did not find those on this year’s visit, and grasshopper numbers generally were low, probably because of the presence of six-lined racerunners.

A Seidner racerunner. I have found that areas with this lizard around the southern end of Lake Michigan have relatively low numbers of grasshoppers.

In one corner of the property, I did find an interesting population of band-winged grasshoppers. They were living on a pale gray substrate, and they were so well camouflaged that even when I saw where one had landed after I flushed it into flight, it took some time to see it. They reminded me of ghost crabs I have seen on tropical beaches, and so I thought of them as ghost hoppers.

As you can see, these grasshoppers very nicely match their substrate.

I had a guess as to their species identity, and took a series of photos needed to back it up.

A dorsal view showed that the rear edge of the thorax pronotum is blunt-pointed.
The hind tibias are red, though pale.
The inner hind wing is yellow, but again very pale.

These points, plus the insects’ size and proportions, supported my initial guess of Boll’s grasshopper (Spharagemon bolli). I have found this species to be somewhat variable in color in different locations, and in this case I suspect that the racerunners, foremost among local predators (especially of nymphs), have selected for the ghostlike color pattern.

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Cicada Surprise

June 22, 2023 at 6:35 am (singing insects)
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by Carl Strang

A year from now is the anticipated main emergence of Brood XIII periodical cicadas in northeast Illinois and adjacent states.

We have two species of periodical cicadas, Linnaeus’s 17-year cicada on the left, Cassin’s 17-year cicada on the right.

Though the main body of the cicada populations appears at 17-year intervals, each time there are a few individuals that come out a year early (I call them “oops cicadas”). I heard a couple cicada songs on June 6, and would have thought little more about it, but a couple correspondents let me know they had seen surprising numbers emerging in their neighborhoods. I made a list of the places where I had observed significant numbers in 2020 (explained below), and started checking them on June 10.

As expected, some of the sites I visited that first afternoon had no singing cicadas, or at most a few scattered individuals. I was surprised, however, to find some small areas that had large enough numbers to produce wave choruses with both species singing. Levels of periodical cicada numbers singing in an area increase from scattered individuals, to greater numbers that nevertheless are countable, to small unorganized choruses, and conclude with groups that are so large the volume of their (loud!) singing rises and falls in organized synchrony. Most of the singers were Cassin’s 17-year cicadas (Magicicada cassinii), but some of the wave choruses were accompanied by a few of the slightly larger Linnaeus’s 17-year cicadas (Magicicada septendecim). Here is an excerpt from my recorded notes at one of the wave chorus sites:

If you look up in such places you can see cicadas flying in the treetops, while close to the ground you can find the emptied shells left behind when the nymphs come out of the ground and their adult forms break free.

One of many nymphal skins at one of this year’s wave chorus sites

So, what is going on here? In several blog posts in 2020 I shared results indicating that huge numbers of periodical cicadas not only emerged four years ahead of time in some of Chicago’s western suburbs, but that significant numbers of them successfully reproduced. It appears we now have two temporally separated populations of the two species (such 4-year-early emergences also were documented here in 1969, 1986, and 2003). Climate change has been suggested as a possible stimulus (based on the observation that farther south, periodical cicadas emerge at intervals of 13 rather than 17 years). I favor a different hypothesis, proposed by Lloyd and White (1976. Evolution 30:786-801). They suggested that population pressure, experienced by the nymphs as excessive aggressive encounters with one another underground, stimulates a portion of them to come out early. Other more recent results suggest that these insects count years in groups of 4, deciding a year ahead of time when they will mature, so a 4-year-early emergence makes sense. In 2020 it was clear that the big numbers appeared only in residential neighborhoods, not in the forests. Predators are relatively few in residential areas, so that population sizes could become untenably large and stimulate an early escape.

That brings us to this year. It is one year ahead of the main emergence in northeast Illinois. Could it be that populations are so intolerably dense in some spots that some of their members simply can’t wait one more year? The fact that most of the areas with wave choruses in 2020 did not produce such big numbers this year, while a few did, may reflect different stages of population growth taking place in different locations.

In this map of DuPage County, the 2007 areas with large periodical cicada numbers are marked in pink. More brightly colored spots map the 2020 emergence. White dots indicate towns or parks in which at least one or a few cicadas were documented. Yellow dots mark countable numbers, i.e. from one spot you could hear multiple cicadas singing. Orange dots mark small choruses (though sometimes occurring over large areas), in which the cicada songs were blended to the point where individuals no longer could be picked out, but the choruses were not organized. Red dots mark areas with full choruses, formed into periodic waves of song, loud and with both species audible. Many of those dots have elongate shapes because they came out of driving surveys along streets. It is likely that the unmarked areas between some of them were filled with wave choruses.

This month I returned to the areas where there had been wave choruses in 2020. Most of them had few cicadas or none (also true of the areas outside DuPage, in Cook and Will Counties). Four or five had unorganized chorusing. The black dots that I have added to the map indicate this year’s wave chorus locations. None of those seven covered large areas, most being less than a square block.

Next year will be a busy one for me from late May through June. If the Lloyd-White hypothesis is correct here, I would expect all these areas again to have enough cicadas to produce wave chorusing. But then again, they may have more surprises in store.

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Kankakee Sands Bioblitz

June 13, 2023 at 7:23 am (plant-eating insects, reptiles and amphibians, singing insects)
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by Carl Strang

This year’s bioblitz, in the series sponsored by the Indiana Academy of Science, was a return to the site of the first such event that I joined in 2012, the Kankakee Sands Preserve in Newton County. The 2012 bioblitz took place in late July, so with a June 3 date this year there were fewer singing insects to observe. I sought without success to find new species to add to my site list, and ended up with 5 singing insects. Some were expected this early:

Sulfur-winged grasshopper, Arphia sulphuria

Others gave me first song dates for the year:

Eastern striped crickets (Miogryllus saussurei) were singing a week earlier than I had observed in any past year. This female climbed up onto one of the evening’s lit sheets.

When bioblitzes are scheduled this early in the season, I like to set up a sheet with a UV light in the evening and photograph moths. I also visit sheets operated by the Purdue University beetles team. Moths, especially their caterpillars, are ecologically significant and deserve attention in the bioblitzes. Here are some of the more attractive ones from this year.

The birch dagger (Acronicta betulae) is regarded as uncommon. Its larvae feed on river birch leaves.
I photographed three dagger moth species. The great oak dagger (Acronicta lobeliae) was at home in the Conrad Station oak woodland.
The white-spotted leafroller (Argyrotaenia alisellana) is another oak specialist.
Tulip-tree beauty (Epimecis hortaria)
Buck’s plume moth (Geina bucksi) is tiny, but its beautiful pattern deserves a close look.
Green leuconycta (Leuconycta diphteroides)
Moths need to be looked at closely, because there can be color variation among individuals of the same species. Here is one disparaged arches (Orthodes detracta).
And here is another, which a first glance suggests must be a different species.
Faint-spotted palthis (Palthis asopialis)
Virginian tiger moth (Spilosoma virginica)

Pickings may be slim for singing insects in early-season bioblitzes, especially in more northern sites, but the opportunity to experience this nighttime diversity, and also the company of other researchers specializing in other groups of organisms, makes the trip worthwhile. There always is more to learn. For instance, while driving to Conrad Station at dusk, I stopped to escort a snake off the road.

I would have passed it off as a fox snake, but one of the more herpetological participants looked at the photo and taught me the differences between this bull snake and the fox snakes with which I am more familiar.

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Another Season in the Books

October 30, 2022 at 6:17 am (singing insects)
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by Carl Strang

In earlier posts I outlined the most significant finds in this year’s research on singing insects. The season was sprinkled with smaller delights, too, and I am pleased to call it successful. My game plan emphasized visiting new sites and trying to plug distributional holes for some species. I looked at 11 new sites, added 20 county records for all species combined, and closed the book on three species, i.e., I now have found them in every county or, at least, every county where I expect to find them. Those were the gray ground cricket (Allonemobius griseus), which I found at Chicago’s Montrose Park on September 6 for a Cook County record; the four-spotted tree cricket (Oecanthus quadripunctatus), which I now have documented in all 22 counties of my study region; and the oblong-winged katydid (Amblycorypha oblongifolia), which stubbornly had refused to reveal itself in LaPorte County, Indiana, until I heard a few singing on August 6 at Kingsbury Fish & Wildlife Area.

I also found new north locations for two of the species that are expanding their range from the south: the slow-tinkling trig (Anaxipha tinnulenta) at the Grand Mere Lakes in Berrien County, Michigan, and the handsome trig (Phyllopalpus pulchellus) at the northern end of Grassy Lake Forest Preserve for a Lake County, Illinois, record.

Now for a few photos of critters found along the way. I wanted to clarify the relatively early, long-trilling tree crickets I have been hearing at DuPage County’s Springbrook Prairie Forest Preserve. These proved to be a mix of four-spotted and Forbes’s (O. forbesi) tree crickets.

Forbes’s tree cricket from Springbrook Prairie, temporarily chilled for photographic purposes

I had visited Cook County’s Penny Road Pond preserve a few times before, but this year got into a large part of it that was new to me.

Texas bush katydid (Scudderia texensis), a site record for Penny Road Pond.

One of the new sites I visited was Spring Lake Forest Preserve in Cook County. As I walked a woodland trail I saw an interesting looking grasshopper, which I concluded was a sprinkled grasshopper (Chloealtis conspersa). This was the year’s second county record for the species, the first being the subject of an earlier post.

Sprinkled grasshopper nymph at Spring Lake

The remaining two photos are from a September 2 visit to Pulaski County, Indiana.

This female spotted ground cricket (Allonemobius maculatus) at Tippecanoe River State Park posed to give me a better photo than I have taken in past encounters with the species.
I continue to be impressed by ovipositor lengths in female straight-lanced meadow katydids (Conocephalus strictus) like this one at the Winamac Fish & Wildlife Area.

Looking ahead to 2023, my top priorities again will be visits to new sites, and efforts to conclude searches for species in counties where I have yet to find them but where they are likely to occur.

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Dusky-faced Year

October 22, 2022 at 6:29 am (singing insects)
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by Carl Strang

My study of singing insects in the Chicago region is mainly distributional, as I map out the locations where I find the 100+ species of singing crickets, katydids, grasshoppers and cicadas. There are some overarching themes, however. I am interested in the several species that have expanded their ranges northward, and are continuing to do so. The landscape ecology of these insects provides many illustrations of that relatively new field’s power. One of the most important findings, however, is the identification of species that are so uncommon as to be in possible danger of regional extinction. I pointed to one of these, the stripe-faced meadow katydid (Orchelimum concinnum), in the previous post.

For most of the years of this study I had a similar concern over the dusky-faced meadow katydid (O. campestre), a close relative of the stripe-faced. This year’s results have relaxed that worry, as I have found the species in six more places.

Female dusky-faced meadow katydid at Romeoville Prairie Nature Preserve, Will County, Illinois
Male dusky-faced meadow katydid at Seidner Dune and Swale Nature Preserve, Lake County, Indiana

Two of these newly found populations, at Seidner and in the Newton County portion of Indiana’s LaSalle Fish and Wildlife Area, are among the largest I have encountered. I only surveyed part of the expansive Romeoville site, and there is a large wetland in LaPorte County’s Kingsbury Fish and Wildlife Area, which also may harbor big populations.

Map of the Chicago region, showing sites where I have found dusky-faced meadow katydids. Open circles represent counties where the species was known historically, but where I have not yet found it.

Though the species appears to be safe in the region for now, they only occur where native wetland grasses have not been displaced by invasive species such as common reeds, hybrid cattails and reed canary grass. Their fate is in the hands of people managing their wetland homes.

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