Tibicen Song Sorting

July 27, 2010 at 6:13 am (singing insects)
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by Carl Strang

My first entry into singing insects study came when I ran across the University of Michigan cicada website in 2003 or 2004. The site includes recordings of cicada songs, and as I played them I realized that all my life I had been hearing the distinguishable songs of several species without knowing it. These were all members of genus Tibicen, and that summer I recognized three common species in DuPage County.

They look very much alike, and are hard to see when singing high up in trees, so it was well that their songs were distinctive. After a couple years, however, I began to notice that the songs I attributed to one of the three, Tibicen linnei or Linne’s cicada, had two variations and with references I was able to distinguish a fourth common species, Tibicen lyricen, the lyric cicada. The differences among these species and their songs I described in some detail in a post last year.

Recently I was reviewing a wide range of singing insects reference recordings when I realized I need to pay attention again to the songs I have been identifying with Linne’s cicada. The swamp cicada, Tibicen chloromera, has a vibrato very close in speed to linnei’s. It has, however, a percussive quality in each vibration that sets it apart from linnei’s smoother, more wavelike vibrato. I had paid too close attention to written descriptions of the swamp cicada, in both the popular and scientific literature, which imply that chloromera is found only in wetlands and sings only from low perches. In fact I am now finding that at least around Culver, Indiana, chloromera often sings hundreds of yards from wetlands, and at least as often from high trees as from perches in lower ones. I have heard them in forests as well as more open stands. This is in keeping with other Tibicen cicadas, which at least in their singing perches show wide ranges in habitat.

So far I have not heard chloromera in DuPage County. I have found that I need to listen carefully, because when lyricen are singing their first, warmup songs of the day they have a slower vibrato with a percussive quality like chloromera’s.

The two areas I frequent most, DuPage County, Illinois, and Marshall County, Indiana, have different Tibicen species lists though they are only about 100 miles apart. Both are homes for canicularis, linnei, lyricen and pruinosa (the dog day, Linne’s, lyric and scissor-grinder cicadas, respectively). So far, only Marshall County appears to have chloromera, the swamp cicada, but I don’t consider the case to be closed. Marshall County also has a sixth species, Tibicen auletes, the northern dusk-singing cicada, which is associated with sandy soils and so does not occur in DuPage County’s clays.

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Odd Bee Identified

July 25, 2010 at 8:34 pm (insects (other))
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by Carl Strang

The Beespotter folks got back to me in recent days and confirmed that the odd bumblebee I reported earlier was indeed a male Bombus bimaculatus.

This confirms in my mind that bimaculatus is an early-season species in northeast Illinois, as males appear toward the end of a species’ season. In support of that notion, in recent days I have seen increasing numbers of Bombus impatiens, the common late-season short-tongued species, as they replace the declining bimaculatus.

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Bobcat, Maybe

July 20, 2010 at 9:45 pm (mammals, methods)
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by Carl Strang

Yesterday as I approached the Poverty Savanna at Waterfall Glen Forest Preserve with a group of teachers in my Field Ecology class, I looked down and saw this footprint.

The animal that made it had crossed the dirt track when the clay was still rain-softened. The vegetation was dense on either side, and tires of patrol vehicles had obliterated any other tracks the mammal made. This track looked odd enough that I took some time to examine it. The only possible toenail mark is off the tip of the right outer toe. If that is a toenail mark, it is tiny and well off the toe tip, unlike any canid’s toenail. The heel mark is oddly lobed. The footprint is almost 2.5 inches long. The overall arrangement is unlike the tracks of dogs, foxes or coyotes. All of this had me thinking, bobcat.

There have been reports of bobcat signs at Waterfall Glen over the years. I learned that Forest Preserve District natural resources staff heard cries they identified as bobcat one night this past spring. I have made many a winter trip into that southern part of that preserve in search of bobcat tracks, but never have found any. I have seen bobcat tracks perhaps half a dozen times in other parts of the country, so my experience is limited. The weakest point in my case for this footprint as a bobcat track (apart from being limited to just one footprint) is the shape of the heel mark’s anterior margin. There should be an indentation marking the boundary of two lobes. I see a tiny one, enough I think to make the case, but I can’t say that anyone going on just this photo should be convinced.

It is reasonable to think that bobcats may wander widely over the forested area on either side of the Des Plaines River in DuPage and Cook Counties, but I doubt that any of these felids are permanent residents of Waterfall Glen.

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A Week of Firsts

July 18, 2010 at 8:45 pm (singing insects)
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by Carl Strang

The past week brought the true beginning of the singing insects season. Though a full work week and other obligations filled my time, I was able to take advantage of what I have learned in past seasons to make some observations that were valuable to me.

For instance, last year I finally nailed down features of the two-spotted tree cricket’s song that removed my earlier uncertainty. The breakthrough came when I found this male, who had chewed a hole in a grape leaf to create a baffle that amplified and/or directed his song.

Finally seeing one of his kind in action, I was able to define the song of that species by the irregular length of its trills, some reaching 7 seconds’ length or more, the spaces between trills being either very brief, or longer but filled with stuttering sounds, and the strained or discordant quality of the sound.

That discovery allowed me to be confident in identifying the first two-spotteds singing in DuPage County, Illinois, this year, on July 12. That is the earliest song date I have for that species, by 5 days.

I also heard the year’s first ground crickets in DuPage. I had been gone a week, and returned to hear striped (photo below) and Allard’s ground crickets on July 12, and Carolina ground crickets on the 13th (I had heard all three near Culver, Indiana, on July 8). Though not the earliest ever, all three species were singing near the earliest first song dates I have noted for them since my study began in 2006.

Mayslake Forest Preserve is one of the DuPage County sites where there are fall field crickets but no spring field crickets. So, when I heard a field cricket song there on July 14 I marked the beginning of that species’ singing season (female shown).

During First Folio Theater’s evening performance of Twelfth Night at Mayslake I heard a few protean shieldbacks singing, my first record of that katydid species on that preserve (female shown).

Finally, I heard my first sword-bearing coneheads of the year while driving to Culver on the evening of July 16.

There are plenty of other species yet to begin, but it feels like the singing insects season has begun in earnest.

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Roesel’s Katydid Update

July 13, 2010 at 8:50 pm (singing insects)
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by Carl Strang

A year ago I reviewed some of the biology of Roesel’s katydid, a predaceous species native to Europe that has been introduced to North America. I described the data I had begun to collect on the expanded range of that species. Most available range maps show it in a large area of the northeast (it first was observed in Quebec, and has expanded well into the northeastern U.S. with observations as far east as northeastern Ohio). Some maps also show an isolated range area in northeastern Illinois.

A few years ago I found what none of the maps show, that Roesel’s has expanded into Indiana as well. Last year I began to explore the extent of that expansion, finding Roesel’s everywhere I looked, from Marshall County as far south as Logansport and as far east as North Manchester.

This year my own study has been put on hold, as my available time has gone into taking care of my parents. There has been progress, however, as fellow nature blogger Scott Namestik (of Through Handlens and Binoculars) has become interested in this katydid and has found it in a number of counties in northwest Indiana, connecting my Indiana locations with those in northeast Illinois.

In our correspondence we have been considering the possibility that the Indiana and even the Illinois insects may not represent an isolated introduction, but instead may have resulted from a more widespread expansion of the eastern range than anyone has realized. Though singing insects have attracted increased attention from amateur naturalists in recent years, there have been relatively few people studying them, and there is a learning curve in this study. I still have some puzzles to sort out in the identification of common species in my own DuPage County, Illinois, four years after I began to focus on singing insects fairly intensively. We are getting to the end of the Roesel’s season for this year. Nevertheless, Scott and I would be interested in any observations readers may have made of this species between Whitley County, Indiana, and the Cleveland area, or south of Cass County, Indiana, or Kendall County, Illinois. There are reports of Roesel’s in eastern Iowa, as well, which likewise is beyond any published range map I have seen.

A final note in my own observations of Roesel’s was provided by an 8-year-old girl during a nature walk I recently led at Mayslake (where I took the above photo). It became clear that she was hearing the singing Roesel’s much better than I was. She was hearing more of them than I was, she was picking up individual songs sooner than I was, and they were so loud to her ears that she complained once of the volume, when I could hear them plainly but would not have said they were loud. I have taken relatively good care of my hearing, but at 59 years I have experienced a typical loss of hearing, particularly in the high frequency range. When I tried out the SongFinder device  on Roesel’s, I found that indeed their songs are quite loud, and I was grateful again for the invention of this aid to the aging naturalist.

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Cricket Reflection

July 12, 2010 at 9:51 pm (singing insects)
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by Carl Strang

Limited field time this year has prevented my pursuing a couple of my singing insects studies. I had hoped to go around DuPage County filling in my map of areas where spring field crickets are present or absent.

I want to get some idea of the geography of two sibling species, the spring and fall field crickets. There are odd gaps in their distributions. I still hope to get some data on fall field crickets this year, but now we have entered the July overlap period for the two species, so that will have to wait.

In the meantime, I have made an observation this spring that will impact not only the cricket study but also my other geographical studies of singing insects. In retrospect it seems obvious, I should have realized it years ago, but I need to do my mapping on a very fine grain. Mapping any insect species by forest preserve or other large area is just too coarse to provide the biological meaning I seek. I need to map on the finer grain of habitat block, or even smaller. This realization came as I reflected on where I have observed spring field crickets in the past. They are not uniformly distributed, even in what appears to be suitable habitat. They occur in clusters or colonies, with significant spaces between them. As I resume this study, I will need to do my mapping with that in mind.

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Odd Bee, and Tour de France Catalpas

July 6, 2010 at 6:02 am (botany, insects (other))
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by Carl Strang

In the late afternoon of July 4 I was looking out the kitchen window at my prairie garden plots. Bumblebees, Bombus bimaculatus, were swarming the Culver’s root

and wild bergamot.

They were not showing very good fidelity, individual bees frequently going between the flower species rather than sticking to one. Then I saw a bee that immediately sent me grabbing for my camera. Like the bimaculatus it was moving between Culver’s root and bergamot.

This bee was almost all yellow.

What was wrong about it was the black abdominal segment in the middle of the yellow. If not for that, I would have passed it off as a Bombus fervidus. But fervidus should have a black strip between the wings, as in this one I photographed last year:

I did a web search, and found a photo of a bee somewhat similar to this one at a University of Illinois website. It was identified as an aberrant male Bombus bimaculatus. The eyes of the one in my yard seemed small, however, for a male.

Also, it seems early in the season for males to appear unless, as I suspect from last year’s observations, bimaculatus is limited to the early part of the year and is replaced by another short-tongued species, B. impatiens, in the latter part of the season. I decided to resolve this problem by creating an account in Beespotter and submitting my photos to the specialists there. I’ll report back with the results later.

P.S. In last night’s TV coverage of the Tour de France, the broadcast announcers’ table was placed in front of some catalpa trees in bloom. The British and American announcers all wondered aloud at one point what the trees were. I’m not sure which catalpa species it was, but clearly these or their ancestors had been transplanted from North America to that location in Spa, Belgium, for their floral display at this time of year.

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Saddlebags

July 5, 2010 at 6:18 am (dragonflies and damselflies)
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by Carl Strang

I have been seeing unusual numbers of red-bodied saddlebags dragonflies this season. They aren’t exactly swarming, but it seems that every time I go around Mayslake Forest Preserve I see at least one. Saddlebags are a group of relatively large dragonflies in the skimmer family that have patches of color on the bases of their hindwings. Our common one in northeast Illinois is the black saddlebags.

Our least common species, which is a rare wanderer from the Gulf Coast, is the striped saddlebags.

It has a red abdomen, but note the characteristic white stripes on the thorax. I photographed this one in 2004 close to the Des Plaines River. It must have followed the Mississippi River from Texas, then the Illinois River to the Des Plaines to reach northeastern Illinois.

There are two other red-bodied saddlebags we are more likely to see. Not long ago I shared a photo of one at Mayslake, repeated here.

I am not familiar enough with the two species to identify them in flight. This may be a Carolina saddlebags or a red saddlebags. Last week, however, I got a rare opportunity to examine one close up.

This insect was fluttering in the Willowbrook Wildlife Center parking lot, apparently having been caught on the front of a car. At first I was going to call it a red saddlebags, because of the dull red color and the small black spots on the tip of the abdomen. However, the ovipositor on the underside of that tip reveals that this individual is a female. Females can be dull colored relative to males. According to my references the colored area of the wing is much larger in the Carolina saddlebags, matching the extent on this individual. The deciding factor, however, is the forehead.

The forehead is the triangular area between the large squarish tan face and the eyes. There is a dark purple line across the lower half of the forehead on this dragonfly, which in the female marks it as a Carolina saddlebags.

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Insect Phenology June

July 2, 2010 at 5:41 am (dragonflies and damselflies, plant-eating insects, singing insects)
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by Carl Strang

In my previous post I updated first flowering dates for Mayslake Forest Preserve in 2010. Today I’ll share first insect sighting dates for June. In the limited time I had to be out on the preserve during the month I noted only 12 new species for the year. The median difference from last year was a negligible half day earlier. These observations included the reversed haploa (15 days earlier than last year),

and Roesel’s katydid (27 days earlier).

New species for the preserve list included the familiar bluet

and the moth Scopula limboundata.

In English the last is usually called the large lace-border. It belongs to the Geometridae, or inchworm family.

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