Today’s chapter in the Sound Ideas winter series is a recording from the evening of September 4 last year. I made it in the Miller Woods portion of the Indiana Dunes National Lakeshore. Three very different singing insects can be heard distinctly throughout:
The principal target of this recording produced the annoying, continuous buzzing sound. If you had been there, you would have remarked at how loud this insect was. It was a robust conehead.
Male robust conehead, singing posture
This katydid has a sibling species, creatively named the false robust conehead (Neoconocephalus bivocatus). I haven’t documented bivocatus in the Chicago region, but there are a couple old possible records, so occasionally I record an individual and check the pulse rate and pattern. So far, all have been good old Neoconocephalus robustus.
The other two members of that night’s trio both produced regular, brief chirps: one higher pitched and very regular in its rhythm, the other much lower and a little less regular. The higher pitched singer is famous for the way its chirping rate varies with temperature: count the chirps in 13 seconds, and add 40 to get the degrees Fahrenheit. We know this singer as the snowy tree cricket.
Snowy tree cricket male, taking a break from singing to snack on skin.
That leaves the bass section. The lower pitched continuo is the product of a northern mole cricket. This swale area of Miller Woods is one of only 3 locations where I have found this species to date. I don’t have a photo to show you. True to his name, the mole cricket sings from within his tunnel, and I haven’t yet had a photo op with the critter.
Ah, yes. I see an insistent hand upraised in the back of the class. Yes? Ah, very good. Yes, there is a fourth, more intermittent performer here. Those few added chirps are a fall field cricket’s, practically ubiquitous at this point in the season, and determined to insert himself into any ensemble.
A continuing theme in my regional survey of singing insects is the paucity of wetland species. The only one that is present in good numbers in many wetlands is the black-legged meadow katydid. Other species common in wetlands are habitat generalists such as the Carolina ground cricket and short-winged meadow katydid, which don’t truly count as wetland insects. One clear cause of this problem is the loss of high quality habitat to four invasive plant species (purple loosestrife, reed canary grass, common reed, and cattails). All four are capable of completely taking over a wetland, and examples of this can be found for all four. Small numbers of the singing insects mentioned above can be found in such places, but not the other wetland insect species.
This female long-tailed meadow katydid was a rare wetland species holdout in a small pocket of surviving diverse wetland plants surrounded by cattails, reed canary grass and common reed at Waterfall Glen Forest Preserve in DuPage County, Illinois.
On the other hand, there are some good wetlands out there. Many are small, and this along with their isolation may limit them.
This beautiful little fen at Richard Young Forest Preserve in Kendall County is completely surrounded by woodland.
Many of the interdune swales at Miller Woods in the Indiana Dunes National Lakeshore have been taken over by the common reed. This one was an exception, but I found only black-legs there.
This fen-like wetland at Bluff Creek in Wisconsin’s Kettle Moraine State Forest looks very good. I will want to check it earlier in the season next year.
Still, I have not given up hope. I found a third good population of mole crickets this year, in a swale at Miller Woods.
Mole cricket tunnels look like miniature mole tunnels. They occur around wetland edges, and occasionally have holes to let out the males’ deep chirping calls, and to provide access for attracted females.
I also found melodious ground crickets at two new sites in Berrien County, Michigan. Though I did not find dusky-faced or delicate meadow katydids at the Indiana Dunes’ Great Marsh this year, I felt curiously encouraged by this.
Both species were there last year, but with the water level higher in 2013, the vegetation was arranged differently and I did not find them in the same place.
Maybe the populations of many wetland species took a hit in last year’s drought, and were thinly dispersed in the expanded wet areas of 2013. This is, after all, the first year in which I have surveyed many of these sites. If they need a couple years to recover from the drought, maybe I will find the missing species in the future. Still, how to account for the lack of nimble meadow katydids? This species I have yet to find, anywhere. In the heart of the singing insect season I took my sea kayak into an area where they historically were known.
The channels at the south end of Lake Maxinkuckee in Marshall County, Indiana, have become heavily invaded by purple loosestrife.
Even the patches of emergent water-dwelling knotweeds, a habitat specifically mentioned in some sources as good for nimble meadow katydids, had none as far as I could tell.
So the bottom line is a disappointing season for wetland species, with a few positive points and hope in the possibility that populations are at a low point from which they will recover.
It should be obvious that this title is not a political reference. In this election year both political conservatives and liberals are easy to find as they loudly and shrilly make their cases against each other, trying to attract voters (hm, reminds me of singing insects for some reason). The conservatives I am concerned about here are some of the wetland species of singing insects, habitat specialists that are found only within narrow ranges of ecological parameters and are sensitive to invasive species and other disruptions. Much of my research this year is focused on finding conservative species from my hypothetical list for the region.
I haven’t had a lot of luck with wetland conservatives. The northern mole cricket was one, but I still have not found them anywhere but Houghton Lake. The marsh conehead was another. We thought we also found slender coneheads at Indiana Dunes National Lakeshore, but Gideon discovered when he returned to his lab that they all were marsh coneheads as well, misleading because they were outside the size range of that species he was familiar with in Missouri.
Gideon also learned that the underside of the cone should be black, not gray as it was on the marsh coneheads we found.
But what about the several species of wetland meadow katydids in genus Orchelimum? Regionally there should be four species I haven’t yet found: dusky-faced, stripe-faced, delicate and nimble meadow katydids all have been elusive. I should have found dusky-faced meadow katydids, at least, because they are described as being common in a wide range of marshes. Instead I am finding lots of black-legged meadow katydids, a marsh species that spills into drier areas adjacent to wetlands.
Black-legged meadow katydid
Black-legs sing so loudly, day and night, that I wonder how earlier researchers heard the other wetland species. I wonder if black-legs have become more abundant, conceivably pushing the others out. Have I not been looking in the right places or in the right way? Is the lack of success this year a consequence of the drought? Certainly it takes some effort this year to get wet feet in the marshes. I will continue to look. Last week at Chain O’Lakes State Park in Illinois I saw a number of Orchelimum nymphs that were relatively plain and green.
This female meadow katydid nymph is recognized as an Orchelimum by the curved ovipositor.
On the other hand, black-legs don’t get their full colors until after they mature.
This newly molted adult male black-legged meadow katydid still has not developed his full coloration.
I will continue to look this year, and hope for better conditions next year.
Another area near Culver, Indiana that I wanted to check for singing insects was the Maxinkuckee Wetlands, a state conservation area. Much of it I will need to access by kayak on another occasion. My daytime visit did not produce much, but when I returned at night I was pleased to find a population of slightly musical coneheads, which I first had encountered in the previous week at Indiana Dunes National Lakeshore.
Unlike the mole cricket, as mentioned in yesterday’s post, the slightly musical conehead has a buzzing song.
Along the road edge of the property I heard a different conehead, and traced the song to a small oak.
The impressive volume of the song up close was enough to confirm the singer as a robust conehead. The dry habitat and cone free of black markings support the identification.
Maxinkuckee Wetlands is another site calling for continued exploration.
A priority site in this year’s singing insect survey work was Houghton Lake, a Nature Conservancy property near my home town of Culver, Indiana. The muck, marl and sand soils potentially support communities including wetland crickets and katydids that I have not yet found. Last week I spent an afternoon and evening walking through the site.
The property, named for this lake, is of particular interest as it hosts a population of rare massassauga rattlesnakes.
There are many smaller wet areas on the site, which is a flat postglacial lake plain. It has great botanical as well as zoological biodiversity.
For the most part I found a long list of familiar, common species.
Black-legged meadow katydids, like this female, are expected in wet areas.
As I walked the lanes I heard crickets singing in the pattern of Say’s trigs, but with a more mechanical or buzzing sound quality. I spent some time searching, because I thought they would prove to be a species I had not seen before. This effort was rewarded.
The handsome trig is one of the more beautiful singing insects in the region. They are tiny, around a quarter inch long.
Another unfamiliar sound was a rhythmic “warg warg warg” coming from a couple wet prairie areas. The song’s rhythm was like that of slightly musical coneheads, but that katydid produces a call with a distinctly buzzing quality. A comparison of recordings led me to the northern mole cricket. The mole cricket’s song is a chirp, but so deep that it is not readily characterized as such. Like the handsome trig, this was a species new to my experience. For future monitoring purposes I was pleased at how far their songs carry, and that at least sometimes they can be heard singing in the mid-afternoon.
A few conehead nymphs turned up in sweep net samples.
These probably will prove to be round-tipped coneheads, which mature later than most of their relatives.
An additional interesting insect was a great blue skimmer.
This was only the third individual of this species I have encountered.
Most of the conservative species I’d hoped to find at Houghton Lake eluded me, but I was only able to see part of the site, and I intend to return.
This week’s absent insect in my singing insects study is the northern mole cricket. Records from past studies include northeast Illinois and northwest Indiana in its range.
I have childhood memories of raised tunnels in the mud of Indiana marshlands that resemble those of moles in miniature. I have yet to find mole crickets in my current study, however. Records in the Singing Insects of North America database (SINA, the source of the map above) place it in several counties in the region. I have not found it in DuPage County, but it could be here. I will continue to look and listen for this species in muddy shallow marshes in northeast Illinois and northwest Indiana.