Roesel’s Katydid Quest

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.

Roesel's katydid female 2b

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.

Roesel's katydid b

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.

Manchester College 3b

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.

Roesel's voucher b

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.

Roesel coll site 2b

I found a larger than usual area of unmowed mixed grasses and forbs there.

Roesel coll site 3b

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.

8 Comments

  1. Burt Walker said,

    July 2, 2009 at 5:09 pm

    Hi Carl,

    I took a picture of what I thought was a grasshopper a couple of days ago sitting on a cordgrass leaf blade in my “prairie patch” in my back yard. Because of the distinctive marking on the side I became curious as to what species it was, so e-mailed the picture to the entomology dept at U of I. Mr Isaac Stewart replied today that it was Roesel’s Katydid. In “googling” this subject, here I am at your blog! Glad to find it! If you send me your e-mail address, I can e-mail you the picture I took, if you are interested.

    Regards —- Burt Walker

  2. Burt Walker said,

    July 2, 2009 at 5:15 pm

    Hi Carl,

    Forgot some useful information — location of “my back yard”. I live just a little NW of St. Charles, near LeRoy Oakes Forest Preserve

    Burt

  3. June 12, 2010 at 2:47 pm

    Hi Carl. I was walking the dog this afternoon on my property in North Liberty, Indiana and heard an electric buzzy singing insect that I thought sounded like some kind of meadow katydid. When I found the culprit, I thought it looked like a short-horned grasshopper, until I saw the long antennae, and then saw him singing. I immediately noticed the yellow-green crescent behind the head. I came inside to check resources and found that it appeared to be a Roesel’s Katydid. I thought I might have a state record non-native insect, until I did a search and found your blog post. I’m assuming Roesel’s Katydids are now widespread in northern Indiana. Did you report your find to anyone? Is there anyone to whom a find such as this should be reported?

    • natureinquiries said,

      June 14, 2010 at 12:37 pm

      Hi, Scott,
      Roesel’s has been one of my interests in recent years. Last year I found them around Logansport and North Manchester, and your observation connects them back toward northeastern Illinois where they originally were established. I had hoped to extend the search to Lafayette and perhaps toward Fort Wayne this season, but it looks like that will have to wait for another year. I’m not aware of anyone in Indiana who would be interested. I have passed my observations along to the Singing Insects of North America website. Once I have a sense of how far they have spread, I’ll be better able to say what is happening with them.

      • June 15, 2010 at 7:36 pm

        Hi Carl. Found more Roesel’s Katydids in Lake County, Indiana today, at a large wetland restoration in Lake Station. Add another county and link to the Illinois populations to the dot maps. They were mostly in disturbed upland areas. Lots of them, I would say. I wonder if we should consider doing some surveys and writing a paper. I noticed a paper in Journal of the Acadian Entomological Society about new records of this species in New Brunswick in 2009.

      • natureinquiries said,

        June 16, 2010 at 11:23 am

        Sure. I’d like to have some sense of how far they’ve gone, and especially to measure the rate of spread per year.

  4. June 16, 2010 at 7:16 pm

    Hi Carl. Send me an email at snamestnik@jfnew.com. Do you have ideas on what amount or type of sampling would be necessary? Could it be as simple as visits to random places in northern Indiana and northeastern Illinois at the time of year when Roesel’s Katydids are singing, moving south as we go until we don’t find them anymore?

  5. July 13, 2010 at 8:50 pm

    […] year ago I reviewed some of the biology of Roesel’s katydid, a predaceous species native to Europe that has been introduced to North America. I described the […]


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