Return to the Dolomite Prairie

by Carl Strang

I needed to return to the dolomite prairie at Waterfall Glen as part of my targeted singing insects search. This had been my dragonfly monitoring area until I switched to surveying the nearby Des Plaines River by kayak, and I hadn’t been in the dolomite prairie for two seasons.

This is a unique environment, arguably the rarest in the county, as it is a prairie growing in a thin soil layer that has developed atop a shelf of Silurian dolomite bedrock in the few thousands of years since the last continental glacier melted away. In my dragonfly monitoring there I had seen federally endangered Hines emeralds hunting a few times. This prairie is not established as a Hines breeding area, though they are known to reproduce nearby. As I walked through the drier part of the prairie depicted above, I noticed some meadow katydids, including this female straight-lanced.

My particular interest, though, was a small area of tall sedges and grasses in the wetter east end of the prairie.

This is where I took the photograph of the female katydid nymph I shared a couple posts ago, the brown one that might have been a black-sided, might have been a long-tailed. Almost immediately as I entered the area I began to see a few black-sided meadow katydids, including this female.

But that wasn’t all. In addition to one of the highest densities of black-legged meadow katydids I’ve ever encountered, I also began to see all-brown individuals including this female.

This was almost certainly a long-tailed meadow katydid. According to one paper I’d read, as of 1983 at least there were no known places where black-sided and long-tailed meadow katydids occurred together. I don’t know whether that has changed in the quarter-century since that publication appeared, but if not then this could well be the first documentation of such a co-occurrence. Considering the potential significance of this find, I went ahead and collected one of the all-brown males, while taking close looks at others like this one.

It proved indeed to be a long-tailed meadow katydid. As I sampled the area with my sweep net I also turned up some colorful individuals like this one.

It has a brown body, and in fact except for the green legs is much like the all brown long-taileds. I was tempted to regard these as variants of the short-winged meadow katydid, a much more common species, because some of them had very bright yellow abdomen tips.

In the end, though, I had to conclude that this was a population of long-tailed meadow katydids with both brown-legged and green-legged individuals. Photos supported the structure of the green-legs’ cerci being closer to long-taileds’ than to short-wingeds’, and while in the literature I could find some references to long-taileds with green legs I could find no mention of short-wingeds with brown bodies.

Thus this small area at the east end of the dolomite prairie, which also is the only part of the whole site where I have seen Hines emeralds hunting, proves to have considerable scientific value. Unfortunately it may be on the verge of being lost. It is smaller than it was even two summers ago, as reed canary grass is invading and displacing the tall sedges and native grasses. I don’t know if anything can be done about this. Herbiciding the reed canary grass probably would also do in the native species, and as I understand it there are no other options. I have to hope the Hines’ can hunt elsewhere, and that these meadow katydid populations will be able to hang on in the marginal habitat with which they will be left if the trend continues.

%d bloggers like this: