The Currency I Work in

by Carl Strang

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.

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.

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.

Roesel’s katydid

Roesel’s 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

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.

Parson’s Grove Visit

by Carl Strang

One evening last week I paid a visit to Parson’s Grove at Danada Forest Preserve. I felt that Nebraska coneheads were due to start singing, and Parson’s Grove has the largest population I have encountered in DuPage County, which makes it the northernmost significant population I have found to date in the Chicago region. There seemed to be more individuals singing that night than I remember from previous years. I tracked one down for a photo.

He proved to be a brown one. The conehead katydids all can be green or brown, but this is the first brown one of this species I have seen.

He proved to be a brown one. The conehead katydids all can be green or brown, but this is the first brown one of this species I have seen.

Another goal was to photograph a male rattler round-winged katydid, if any were going there. I have photos of a couple females, but lacked one of a male. I heard three at Parson’s Grove, and caught one in the open on a giant ragweed leaf.

My headlamp didn’t seem to disturb him as he casually groomed his feet.

My headlamp didn’t seem to disturb him as he casually groomed his feet.

The brown area on his back, which is part of the wings’ song-producing apparatus, is one distinguishing feature of males.

Parson’s Grove is a great place to hear a wide variety of nocturnal singing insects. DuPage County’s forest preserves provide a huge advantage to the region’s nature lovers, in that the preserves close an hour after sunset rather than right at sunset as is the case in the less enlightened surrounding counties.

OK, Spring

by Carl Strang

In my idiosyncratic 6-season calendar, Late Winter begins March 1, and ends on the day that I see the first native wildflower blooming away from the warming influence of buildings. Last week that criterion was met when I saw a spring beauty flowering in Parson’s Grove at Danada Forest Preserve. This was a little earlier than usual, but we’ve had plenty of warm weather to date, so that is to be expected.

Spring beauty, though not this year’s first. Didn’t have a camera on me.

Spring beauty, though not this year’s first. Didn’t have a camera on me.

Yesterday many spring beauties were in bloom at St. James Farm as well.

 

Coneheads

by Carl Strang

The singing insect season is drawing to a close, and I have not mentioned one group to which I devoted some attention this season. The coneheaded katydids are a fairly diverse group of relatively large katydids characterized by cone-shaped structures that rise from the tops of their heads.

Nebraska conehead b

This is a Nebraska conehead. Its song consists of loud, shrill buzzes about 1.5 seconds long, with 1-second pauses between. It sings starting at dusk, in habitat that in my experience always has bushes and usually trees. The only location I have found so far with more than 3 or so singing individuals is Parson’s Grove at Danada Forest Preserve. The scattered bushes against the savanna edge seem to be ideal for this species.

There are two common, widely distributed coneheads in DuPage County’s meadows and prairies. The first to start singing, in the second half of July, is the sword-bearing conehead.

Sword-bearing 2b

Its rapidly ticking song has been compared to the sounds of a distant steam engine or a sewing machine. The other common meadow species is the round-tipped conehead.

Round-tipped conehead 3b

As you can see, these katydids look much alike. The round-tipped has a relatively short cone with a small black area at the tip (compare to the longer cone with a nearly all black surface on the Nebraska conehead, above).

Round-tipped conehead 5b

This one is more of a late season species, starting up in the second half of August and continuing through October. Its song to my ear is much like that of the Nebraska conehead, except that it has very long continuous buzzes rather than interrupted ones.

The possibility that I need to clear up is whether the robust conehead also is present. Its song is continuous, like that of the round-tipped, but reportedly is much louder and at a lower pitch. Its similar cone typically lacks the black tip, and body size is larger. I may have heard some of these at night while driving in past years, but so few in 2009 that I will have to hold this possibility for investigation until next year.

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