by Carl Strang
Earlier I featured northeast Illinois’ common native predaceous katydid, the protean shieldback . We have another predaceous katydid, an import from Europe, Roesel’s katydid. Here is a female. Note the general brown color, and the yellow-edged half-moon of black behind the head.
This is a species of open prairies, meadows and roadsides, preferring a mix of tall grasses and forbs. Here is a male in singing posture.
There are two things to note in comparing the two photos. First, the female is recognized by the curved, bladelike ovipositor protruding from the back of her abdomen. A structure of this sort is present in all female crickets and katydids. Second, note the long wings of the male and the short wings of the female. This is not a gender difference, as either gender can have either wing length. The male’s singing structures are in the basal part of the wings, and are complete in short-winged individuals.
Range maps for Roesel’s typically show it in a fairly large area of the northeastern U.S. plus a separate, smaller area in northern Illinois. I expected to find it in DuPage County. It is indeed abundant here, and I have found it in Kane and Kendall Counties as well. Imagine my surprise two years ago when, riding my bicycle around Culver, in north central Indiana, I started hearing the distinctive flat buzzing songs of Roesel’s katydids. I interrupted my workout to find one, and confirmed its identity visually. I intended to begin exploring the extent of their range extension last year, but a bike fall in mid-June gave me a broken collarbone and rib, forcing a postponement.
Last week I took a couple vacation days and searched for Roesel’s in two additional Indiana areas. First I drove to North Manchester in Wabash County, home of Manchester College.
I covered 25 miles of country roads on my bike, and found scattered Roesel’s both west and east of North Manchester. I collected a voucher specimen.
I’m not fond of killing insects, but in this case felt the need for a voucher to support my claim. For what it’s worth, the greatest concentration of them was at the intersection of county roads 1400N and 300W.
I found a larger than usual area of unmowed mixed grasses and forbs there.
That was the source of the voucher specimen. The next day I drove down to Logansport for another prospecting bike ride. In a 22-mile tour of Cass County roads from the Wabash River north, again I encountered Roesel’s katydids regularly along the way. As on the previous day there were plenty of spring field crickets, too, plus a number of common meadow katydids, the first I’ve heard this year.
Roesel’s song is a mechanical sounding buzz, lengthy but with occasional interruptions. Nothing else produces a sound like it so early in the season. The males usually begin singing around mid-morning (though on a hot day I have heard them as early as 7:15 a.m.), and continue through the heat of the afternoon. In northeast Illinois the earliest appearance I have noted was June 10 (in 2007), latest June 22 (last year). They continue into the second half of July (the latest I have heard one was July 28 in 2006). For recordings of the song, go here or here . You also can see the conventional range map, which clearly needs updating.
