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.

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McHenry County Visit

by Carl Strang

On September 3 I drove up to McHenry County, Illinois, to continue my regional survey of singing insects. I spent most of that hot afternoon at the Pleasant Valley Conservation Area.

This county park has some very good woodlands and savannas.

This county park has some very good woodlands and savannas.

The day produced 7 county records.

My first four-spotted tree cricket in McHenry was at Pleasant Valley.

My first four-spotted tree cricket in McHenry was at Pleasant Valley.

A shift to the Hickory Grove Conservation Area produced additional observations, some of them remarkable.

The most unexpected find was a small group of gladiator meadow katydids, still singing weeks after they normally are done.

The most unexpected find was a small group of gladiator meadow katydids, still singing weeks after they normally are done.

The photo shows the characteristic pronotum profile and cerci. The marsh habitat and the distinctive song pattern, with the ticks finishing, rather than preceding, the buzz portion of the song all were consistent with gladiator meadow katydid. The black spots on the abdomen may be signs of a parasite load; could that have delayed the completion of development?

The same site produced this marsh meadow grasshopper.

The same site produced this marsh meadow grasshopper.

The Lyons Prairie and Marsh, administered as part of Hickory Grove by the McHenry County Conservation District, actually is in Lake County. I followed the trail into a portion of the marsh dominated by reed canary grass. In addition to abundant slender and short-winged meadow katydids, I got an intriguing glimpse at a female Orchelimum that might have been a dusky-faced meadow katydid, which I have yet to find in Illinois. I was unsuccessful in getting a better look in that late afternoon, but at some point I need to get back there for a thorough search.

On the way back to the car I spotted this tiny grasshopper. Mature at around 3/8 inch long, it is a non-singing species, the black-sided pygmy grasshopper.

On the way back to the car I spotted this tiny grasshopper. Mature at around 3/8 inch long, it is a non-singing species, the black-sided pygmy grasshopper.

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