by Carl Strang
Earlier I related my error in previously identifying DuPage County’s abundant, early-season large meadow katydid as the common meadow katydid, Orchelimum vulgare. This spring I discovered that the correct ID is the gladiator meadow katydid, O. gladiator. It turns out that the two are physically very similar, and there seemed to be some ambiguity in reference recordings of their songs. Last week I was at Meacham Grove Forest Preserve, mainly in search of late season Pachyschelus beetles, about which more will be forthcoming this fall or winter. Reaching Meacham’s west woods requires a walk across the meadow- and wetland-dominated eastern part of the preserve. Where the trail crossed the preserve lake’s inlet stream, I heard rattling buzzes that sounded like the songs of gladiators. This required some investigation, as gladiators elsewhere had finished singing weeks earlier. I found one, and it proved indeed to be a gladiator. But farther along the trail, approaching the pedestrian bridge over Bloomingdale Road, I heard a different song. This was a loud, tick-and-buzz Orchelimum song, but the ticks were more spaced and the buzz was very tight, making it distinct from the songs both of the gladiators I had just heard, and of the black-legged meadow katydids that also had been singing along the stream. This insect was in a dry meadow, singing from the exposed top of a sweet clover plant.
I photographed him, recorded his song, and then reluctantly collected him. He proved to be a common meadow katydid. The cerci, or reproductive claspers, are distinct from those of the gladiator and just like those in reference drawings for the common. The differences are, however, subtle enough under high magnification that I could not have confirmed them on the live insect. Another difference is the shape of the pronotum, the cape-like structure that covers the top and sides of the thorax. Here is the one on the common meadow katydid,
and here is the one on the gladiator meadow katydid.
Again the differences are subtle, but the side of the gladiator’s pronotum has a simple, uniformly rounded outline with no major zigzags or kinks. That of the common meadow katydid has several turns or bends at the front, bottom and (especially) back edges. Incidentally, there is no mistaking a black-legged meadow katydid for either of the others if you see one:
The best news out of all this is that the songs of these three large meadow katydids of DuPage County’s grasslands and wetlands are distinguishable. The gladiator’s buzz is a long, relatively slow rattling sound, with or without a few preceding ticks. The black-legged meadow katydid has a shorter buzz, of a similar sound quality but distinctly faster, always preceded by 2-4 ticks that are rapid, evenly spaced, and run straight into the buzz. Often, ticks and buzzes alternate in a continuous flow. In my limited experience since first finding the common meadow katydid at Meacham, I have noticed two variations in their songs. The buzz can be very tight and fast, reminiscent of Roesel’s katydid . In that variation the song is very different from both the gladiator and the black-leg. However, some individuals (perhaps ones singing at a lower temperature) have a slower buzz that to my ear is just like that of the black-leg. Confusion is prevented by attending to the ticks. In both common meadow katydid song variations, the ticks are irregularly spaced, farther apart, and more numerous than in the black-leg’s song.