Comparative Block Counts

by Carl Strang

In 2010 I made enough counts of singing insects in the small rural town of Culver, Indiana, to compare them to my block counts in Warrenville, Illinois, of the Chicago suburbs.

I walked around similar sized blocks in the two locations, counting the singing insects I heard. This is the south side of the Culver block.

The species count in Culver was 14; differences in species from Warrenville were the absence of Say’s trigs and common true katydids, and the addition of the lyric cicada.

Three species at Culver were abundant enough and showed enough of a difference in median counts to make statistical comparisons worth trying. Culver had more fall field crickets (median count 6, vs. 0 for Warrenville), fewer striped ground crickets (median counts 9.5 and 17 in the period of time covered by the Culver counts), and no statistically significant difference in greater anglewings (median counts 0.5 and 3.5 in Culver and Warrenville, respectively, during the sampling period,).

The Warrenville neighborhood had few fall field crickets in 2010. They were much more abundant in Culver.

I also heard two unfamiliar songs at Culver that may represent additional species. The first of these sang soon after dark on July 31, from a point off the ground and of the speed and pattern of an Allard’s ground cricket, but composed of dry clicks or ticks rather than notes or tones (listening to reference recordings the next day, I thought the most likely possibility was handsome trig).

During a Culver block count on September 4 I heard another unfamiliar song. The temperature was cool, between 55 and 60F, so the song may have been slowed. It had two parts, each consisting of fairly rapid phrases. The first part’s phrases were like doubled ticks, lispy in quality, produced for several seconds. The second part consisted of single ticks, reminiscent of the greater anglewing, lasting much longer (several seconds), and at a distinctly more rapid rate than in the first part. This pattern seems best to fit some member of the subfamily Phaneropterinae, the false katydids.

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