Fork-tailed Bush Katydid

by Carl Strang

A final gift at Indiana Dunes State Park was of fork-tailed bush katydids singing near the nature center after dark, in the absence of greater angle-wings. Reference recordings of the two species’ songs sound very similar, the single brief buzz of the fork-tailed resembling the alternate song of the greater angle-wing (the latter species also produces an unmistakable ticking sound). Greater angle-wings are very common in northeast Illinois woodlands and residential neighborhoods, but fork-taileds are less so, leaving me wondering if I might confuse them in my surveys. A fork-tailed at the State Park resolved this dilemma.

He was singing in a small tree, just a few feet above the ground.

The fork-tailed’s song is not nearly as loud as the greater angle-wing’s (it is a noticeably smaller insect with narrower, more open wings). The greater angle-wing’s brief song also has a sharp, harshly rasping quality in contrast to the lisping nature of the fork-tailed’s song. Finally, greater angle-wings usually sing from high up in trees. The three fork-taileds I heard at Indiana Dunes all were within 8 feet of the ground. While phonetic renderings can be useful in some cases, I think they can only confuse in this instance: the same or similar syllables (tzip, thisp, etc.) could be used to describe either insect’s song.

Greater angle-wing

Reference recordings commonly are made of captive insects held indoors, with the microphone very close to the singing subject. This makes for a clear, isolated recording, but can produce misleading impressions, as the present case illustrates.

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