A Tale of Two Crickets

by Carl Strang

Most of my field work in the peak month of the singing insects season this year went into pursuing nimble meadow katydids, as described in the previous post, plus going for clarity with two tiny ground crickets. Previously I had learned how to distinguish the songs of Cuban ground crickets and variegated ground crickets, close relatives whose high-pitched trills have weak crescendo beginnings and abrupt endings. That identification requires analysis of recordings in the computer.

Each point represents a different individual’s song. Variegated ground cricket songs (left-hand cluster of points) have slower pulse rates (wing vibration rates) and are higher pitched at a given temperature than the songs of Cuban ground crickets (right-hand cluster).

I knew that both species were widely distributed in the Chicago region, but wanted a more complete picture, so I visited sites in most of the 22 counties in August and September. I made recordings and occasionally succeeded in flushing out crickets for visual identifications.

Variegated ground crickets are smaller than nearly all other ground cricket species, are gray-brown with black lower faces and black backs of their heads.

Cuban ground crickets are slightly smaller than variegated ground crickets and are all black except for their black-tipped white palps.

Cuban ground crickets previously were known only as a southern species until Lisa Rainsong found them in Cleveland and then I found them in the Chicago region. They proved easy to find in all 22 counties.

Map of the Chicago region showing sites where I have found Cuban ground crickets to date.

Variegated ground crickets turned up in every county except Berrien in Michigan, though I had a relatively hard time finding them in the other eastern counties of St. Joseph and Fulton.

Map of sites where I have found variegated ground crickets so far.

Along the way I noted habitat features. Though each species has distinct preferences, there is too much overlap to allow identification on that basis. Cuban ground crickets like open grassy areas such as meadows and prairies. Dry to mesic locations favor them, though on rare occasions I found them in wet habitats. Variegated ground crickets prefer shade, and are more likely to occur where the soil is moist or there are rocks, gravel or patches of bare soil.

Otherwise the only new observation was that Cuban ground cricket songs tended to be shorter, averaging 11.1 seconds to the variegated’s 21.9. The longest Cuban trill was 25.5 seconds, and 30 percent of variegated ground cricket songs were longer than that, up to 104 seconds.

I have a good handle on these two species, I believe, and will be able to concentrate on others in next year’s peak season.

Kayaking for Katydids

by Carl Strang

One of my top goals for the field season just past was to seek out nimble meadow katydids in Wisconsin and Indiana. That called for a lot of kayak trips, as the nimble meadow katydid lives on emergent aquatic plants in relatively deep water. Sometimes you can hear them singing from shore, as at parks on the Grand Mere Lakes in Berrien County, Michigan, where I found them under way on August 10.

Nimble meadow katydid, Orchelimum volantum

On the 14th I headed to Indiana, where a few lakes remained to be checked. I had not found the species in that state in lakes where it had lived in the early 20th Century plus others that seemed like good possibilities. I paddled into the Twin Lakes in Marshall County and found a few nimble meadow katydids singing along the channel separating the lakes. They were persisting on some aquatic knotweed plants growing among the dominant purple loosestrife, an invasive semishrub that supports no native wildlife. No luck at Pleasant Lake in St. Joseph County, but at the final stop of the day I found a substantial population of the katydids scattered around the two lobes of Fish Lake in LaPorte County.

Camp Lake in Kenosha County, Wisconsin, had habitat that looked good for nimble meadow katydids.

Beginning on August 17 I made a few trips into southern Wisconsin. Nimble meadow katydids never had been observed in that state, but I had found a small population at Illinois Beach State Park just south of the Wisconsin border. Camp Lake, showed above, looked promising, but harbored none of the katydids. I went on to check 15 more lakes in southern Kenosha and Walworth Counties, but had to conclude that there are no nimble katydids to be found in Wisconsin.

I have a few more places to check in Illinois, Indiana and Michigan, but the picture is clear that the nimble meadow katydid occurs in just a few widely scattered populations in the Chicago region.

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