If our recent 90-dgree heat and 90-percent humidity levels have you lying around like a dog, you might be tempted to think that we’ve entered the dog days of summer. And, know what? You’d be right. But maybe not for the reasons you’d think.
The dog days are named, not for anything you or your dog may or may not be doing right now, but rather for what the Dog Star, Sirius, is up to. The ancient Romans noticed that when Sirius rose with the sun, the weather turned sultry, and began referring to that time of year as dies caniculares, or dog days.
I’m not an astronomer, so I couldn’t tell you where Sirius is at this particular moment. But I do know of another sure sign that the dog days are here: the appearance of Tibicen canicularis, the dog-day cicada.
The dog-day cicada is one of several Tibicen cicada species we have here in Kane County. As cicadas go, it’s not huge
Last week at Leroy Oakes Forest Preserve, during a session of Summer Nature Camp (or, as we soon began to call it, Cicada Camp), we heard dozens of dog-day cicadas calling from the trees. We also saw no fewer than five cicadas, recently emerged from the ground, shedding their exoskeletons one last time and flying off to meet their mates.
But were these dog day cicadas? Without a field guide handy, I couldn’t be sure.
Tags: Culver, dog day cicada, Linne’s cicada, lyric cicada, northern dusk-singing cicada, scissor-grinder cicada, swamp cicada, Tibicen auletes, Tibicen canicularis, Tibicen chloromera, Tibicen linnei, Tibicen lyricen, Tibicen pruinosa
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.
The late summer days are marked by the droning songs of cicadas in the genus Tibicen. Unlike the periodical cicadas, which appear at 17-year intervals, some of these emerge each year. They sing from concealed perches high up in trees, so we seldom see them alive. Here is one I found shortly after its emergence from the ground on a rainy day at Fullersburg in 2007.
This is Linne’s cicada, Tibicen linnei. Its drone is a rapid vibrato, and it has a wide range of habitats, so you can find this common species just about anywhere there are trees. There are three other common cicadas in this group in northeast Illinois. The one with the song closest to linnei’s is the lyric cicada, Tibicen lyricen. The songs are so similar, in fact, that it took a couple seasons for me to realize this was more than just variation within a species. Here is a specimen of lyricen.
Note that the narrow collar behind the head is black. In the other three local species it is green. T. lyricen also has larger areas of chocolate brown just behind the collar. Its song has an even more rapid vibrato than linnei’s, sounding to my ear like a buzz saw. Song length is different, too. The vibrato portions of linnei songs are 15 seconds long at most (of 29 songs I have timed, only one reached 15 seconds). T. lyricen songs can be more than a minute long; the shortest of 24 songs I timed was 18 seconds. Median song lengths for the two species were 9 and 24 seconds, respectively. The lyric cicada can reach huge densities along rivers, being the most abundant Tibicen along the Des Plaines River at Waterfall Glen Forest Preserve, for instance. They also occur around lakes such as those at Mayslake. Usually they are close to a body of water. Another abundant, wide ranging species is the dog day cicada, Tibicen canicularis.
This one looks very similar to linnei; it is the smallest of the four species. Its song is a high-pitched tone, siren-like, the vibrations occurring so rapidly that there is no vibrato. Song length is short.
I have no photo of the fourth species, the scissor-grinder cicada, Tibicen pruinosa. Though widespread, its numbers always are much smaller than those of the others. I have yet to see one, alive or dead (the photographed specimens were collected dead on the ground by my DuPage Forest Preserve District naturalist colleague Leslie Bertram). The scissor-grinder is the largest of the four. Its song is very distinctive, consisting of long pulses, rising and falling at 1-2-second intervals.
These cicadas all sing in daylight, quieting after dark. The lyric cicada begins early, peaking its singing in the morning but continuing in smaller numbers into the afternoon and evening. Peaks for Linne’s and dog day cicadas are in the afternoon, but they continue to dusk, and a few may start early in the day. The scissor grinder peaks its singing in the late afternoon to dusk, but can be heard at mid-day, too.
For recordings of these cicadas’ songs, go to the Michigan cicada