Tinklers

by Carl Strang

After last year’s field season was done, I learned of the possibility that slow-tinkling trigs (Anaxipha tinnulenta) might be in my study region. Checking this needed to be a high priority this year, because the tink-tink-tink song of this newly described little cricket is very similar to that of the tinkling ground cricket (Allonemobius tinnulus). In fact, I had assumed that all the tinkling songs I had been hearing across the region were from the ground cricket. I sent two of my recordings from past years to Wil Hershberger, the experienced sound recordist, and he gave reason to think that these both were of slow-tinkling trigs rather than tinkling ground crickets, as I had assumed.

I began this year’s quest at Big Marsh, a Chicago Park District site where I heard tinkling songs last year. I began finding the songs, coming from dense, tall vegetation. I saw some trigs in that first spot, and did not see tinkling ground crickets, but that was not decisive because I also could hear the songs of another species, Say’s trig (Anaxipha exigua), in the same spot. The 2014 paper by Tom Walker and David Funk which described the slow-tinkling trig indicated that its general appearance is practically identical to that of Say’s trig.

In a second, more open location, there were tinkling songs but no Say’s trigs were singing. I spent a lot of time on the ground trying to spot one of the singers. Clearly they were 2-3 feet above the ground, which practically ruled out tinkling ground crickets, but I needed more. Though I never saw a singing tinkler, I caught a female trig in the same clump of plants. I photographed her before returning her, and she met the one gross anatomical separator from Say’s trig, having a proportionately longer ovipositor:

My next attempt came a few days later. I traveled to Indiana’s Jasper-Pulaski Fish & Wildlife Area. When I checked in at the site’s headquarters, I heard tinkling songs coming from some tall, dense herbaceous vegetation nearby. I made a recording but did not see any suspects:

 I went on to some woodland edges where I have photographed tinkling ground crickets in the past. Immediately it was clear that the tinkling songs there were different from the ones at the headquarters:

They were quieter, though that could have been because the singers were buried in leaf litter. More significantly, they were faster, the tinkling notes coming at a rate of 8 notes per second rather than 6. That may not seem like much, but I noticed it immediately. If anything, the temperature there was a little cooler, so if all else was equal the rate should have been slower rather than faster. There was no question that these were tinkling ground crickets, which I could see near the recorded individuals.

I went to another more open spot with tall dense vegetation where members of the slower tinkling species were singing. I made a recording, then dug in with my net. I caught two female trigs and a male, which I placed in a container to take home. No Say’s trigs were singing there, so I was hopeful. I set the crickets up in a cage, and to my delight that evening the male began to produce his tinkling song. That was the final confirmation I needed.

So far, my analysis of the sound recordings indicates that tinkling ground crickets have a faster note rate than slow-tinkling trigs at similar temperatures. The pitches (carrier frequencies) of the songs are so similar that these cannot be used to separate the species. There is another difference, however, that Wil pointed out and I can confirm. When the notes are magnified in a sonograph, those of the two species usually have different shapes. First, the slow-tinkling trig:

The largest, brightest notes are those of the trig. The shape is generally horizontal, in this case with symmetrical downward tails at each end. Sometimes the shape is a gentle, nearly flat arc with no tails. Sometimes, however, there is a lower descending tail on the right end. Now, the tinkling ground cricket:

Here there is practically no horizontal portion, the shape angling down and to the right. Sometimes the shape is sharply arched, but the right end almost always shows a longer downward tail. If you look again at the trig’s sonograph, you can see a line of smaller, more rapid notes just above those of the trig. There was an Allard’s ground cricket (Allonemobius allardi), a close relative of the tinkling ground cricket, close enough to be picked up by the microphone. Allard’s has an even more rapid note production than the tinkling ground cricket, but you can see that it shares the note shape of a downward right-hand tail.

Since those initial experiences, I have made a few dozen recordings of tinkling songs in several counties. Often note shape alone is distinctive enough to ensure an identification, but some are ambiguous enough to give me pause. I found that I need to standardize the notes, expanding them so they are 0.2 inches long on the computer screen. All of the songs coming from leaf litter on the ground have been those of tinkling ground crickets, and all of those a foot or more above the ground have been those of slow-tinkling trigs. Tall dense vegetation always has proven to house the trigs. Finally, trig songs are produced at a rate slower than ground cricket songs. All but one of the 18 ground cricket songs had note rates of 8 per second or higher. All but one of the trig songs were at 7.5 per second or lower, and 40 of the 46 were below 7. These all were recordings made at relatively warm temperatures, and higher temperatures were associated with higher song rates. At a few sites where both species were present, the difference was clear.

So in the upcoming annual revision of my guide to the singing insects of the Chicago region I will be adding a page for the slow-tinkling trig, and the site maps of these two species will show only locations for each that I have been able to verify visually or through sound recording analysis. The trigs have proven to be more widespread, and I suspect that in DuPage County, at least, they are increasing.

Striped Faces

by Carl Strang

In early August I went down to Will County to check some new sites for singing grasshoppers. Along the way I stopped at a spot in the Des Plaines Conservation Area where I had found unusual grasshoppers in the past. As before, there were Kiowa rangeland grasshoppers (Trachyrhachys kiowa) in the dolomite prairie area.

This western member of the band-winged grasshopper subfamily is uncommon in the Chicago region.

As I was walking back to the car I turned on my SongFinder, a device which lowers high-pitched sounds, like the songs of many singing insects, so that older ears like mine can hear them. I heard some meadow katydid songs, coming from wet areas, that I decided to check out. To my great surprise I saw a striped face looking up at me from the grass.

I caught it carefully, wanting to document only the second population of stripe-faced meadow katydids (Orchelimum concinnum) I have found in the region.

In addition to the female, which I released after taking the photos, I saw a few others. At some point I need to assess the size of this population. There have been indications that this species is associated with relatively high-pH wetlands, which certainly should be the case in that spot with all the dolomite bedrock so close to the surface.

White Whiskers

by Carl Strang

A very busy field season continues, so I have fallen behind in these posts. Today’s story goes back to the last half of July. I had learned through iNaturalist that one of the singing grasshopper species, historically in my region but which I never had discovered, had been photographed in the south unit of Illinois Beach State Park. I went there on July 21. Soon I began finding them.

White-whiskered grasshoppers (Ageneotettix deorum) are small and beautifully patterned to match their habitat.

They are named for the white antennae. The wings just reach the end of the abdomen, so they are not strong fliers. They mainly jump, sometimes with a bit of wing assist, but then want to sit quietly and count on their camo.

Their habitat reportedly includes bare sand, and that certainly was true were I found them. While I was there I assessed the associated grasshopper community. Another singing grasshopper from different subfamily was the mottled sand grasshopper (Spharagemon collare):

Their brightly colored yellow hind wings stood out when they flew. A smaller relative of theirs, the longhorn band-winged grasshopper (Psinidia fenestralis), also was present in good numbers:

Though these typically have bright red hind wings, at Illinois Beach State Park those wings often are nearly transparent.

Most of the grasshoppers were non-singing species. Among those was Hesperotettix viridis, the meadow purple-striped grasshopper:

A few days later I went down to the Indiana Dunes National Lakeshore, hoping to take advantage of my new knowledge to find white-whiskered grasshoppers there. I couldn’t find any, and in fact all the grasshoppers I saw were strong fliers. Though the habitat looked very similar, one difference was noticeable, the presence of a common predator.

Six-lined racerunners are lizards which like to munch on grasshoppers. Even the good fliers were relatively few compared to Illinois Beach State Park, possibly their nymphs having been culled by the lizards. I have a few more places to check for white-whiskered grasshoppers in future years, but had to move on to other things in 2021.

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