A Pause in the Action

by Carl A. Strang

In the early part of the season, from April to early July, my research focus is on those species of singing insects which matured from overwintering nymphs, plus some small early-season cicadas. This is a minority of species, as most of the crickets, katydids, and singing grasshoppers mature after the middle of July, having wintered as relatively secure eggs and needing time to grow up.

I was able to close the book on northern wood crickets last month, and the story here is a sad one. This forest-dwelling member of the field cricket group had been reported from two northern Indiana sites by W.S. Blatchley in 1903. As far as I know, no one has sought them since then in the northern part of the state. Last year I determined that they no longer occur where Blatchley found them. This year I checked the largest other eight forests in the Indiana portion of my study region. If they ever were there, they are gone now. I suspect that forest fragmentation for agriculture and other purposes is responsible for the loss. Blatchley’s detailed descriptions leave no doubt that he knew how to recognize the species.

This northern wood cricket is from the northernmost site where I know they still occur, Eagle Creek Park in Indianapolis.

I was able to close the book on another southern species, the spring trig, in June.

This tiny, early-season cricket is common in southern Indiana.

I have found a few scattered groups of spring trigs in southernmost Fulton and Jasper Counties in Indiana. A thorough search failed to turn them up in neighboring Pulaski and Newton Counties. I may check again in a few years, on the possibility that the species is expanding northward.

One positive result was finding sulfur-winged grasshoppers in the East Main Street Prairie of Cary, Illinois. This adds McHenry to the counties where I have found the species. They probably occur in every county in my region but are common only on sandy or gravelly soils such as Cary’s kame-like hills. I have learned of another candidate site which may add Fulton County, Indiana, next year.

Sulfur-winged grasshoppers are characterized by bright yellow hind wings, which they rattle in flight to produce their song.

Prairie cicadas started a little late this year. I was pleased to find that management efforts to remove brush from the West Chicago Prairie Forest Preserve near my home appears to have paid off in both rebound of diverse prairie vegetation and an increase in the cicada numbers.

Prairie cicadas, are tiny, around an inch long.

Failure to perform such restoration work has a cost. Once known to occur in Kankakee County, prairie cicadas apparently are gone from there, the prairies having been degraded by brush, teasel and other invasive plants.

A final story is that of the periodical cicadas. In each cycle since 1973, the main appearance of 17-year cicadas in Chicago’s western suburbs has been preceded by a significant, 4-year-early emergence. This happened in 1969, 1986, and 2003. I suspect that in a small part of this area, all the cicadas now have switched to the early time. If you have done the math, you realize that it may happen again next year. One predictor to watch for are what I call oops cicadas, a few individuals who jump the gun by a year, or miss the main emergence and come out a year late. As expected, this has been happening this spring. I have heard 3 individuals myself in two cities and seen photos of the insects from 3 more. Counting and mapping them will be a highlight of next year’s early field season.

I predict that some areas will have good numbers of 17-year cicadas next year.

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Southern Lessons

by Carl Strang

This year’s chapter in the series of annual bioblitzes organized by the Indiana Academy of Sciences took place at Eagle Creek Park in northern Indianapolis on June 2-3. This is early enough in the season that there were few singing insects for me to find, but I was able to gain valuable experience with two southern species that occur or have occurred in the Chicago region.

The first of these is the spring trig.

Female spring trig at Eagle Creek.

This species of tiny cricket first was described in 2014. That is surprising, given its abundance in southern Indiana and its extensive range beyond the state. It proved to be common in a range of habitats at Eagle Creek Park, from woodland edges to grassy meadows.

Spring trigs appear plain-faced to the eye, but bright light and magnification reveal a pattern of fine dark lines.

I learned more about the spring trig’s habitat, and found that I can hear them easily while driving at speeds of 30mph or less. This allowed me to get clarity on the species in the Chicago region. Driving in the southernmost counties, I found widely scattered small colonies in Fulton and Jasper counties, at road edges where wider bands of herbaceous plants were backed by woodlands. In the future I expect to find them in southern Pulaski and Newton counties, too, but not north of there.

Eagle Creek Park also has a large population of northern wood crickets.

The northern wood cricket is a forest species that is smaller and blacker than the spring field cricket, which could be heard chirping in the park’s meadow areas.

The spring field cricket is a few millimeters longer, typically has bronzy wings, and has a proportionately broader head and thorax.

Recordings I made during the bioblitz, and at home with a captive male, have provided further clarity on northern wood cricket song characteristics. Their chirps may never have 4 pulses (commonly 2 or 3), and almost never rise above 5 kHz in pitch, where spring field crickets often have 4-pulse chirps, and seldom drop below 5 kHz. Habitat also helps separate the two. I dug deeper into the literature, and learned more about historical records of the species in two Chicago region counties. Those observations were made in 1902, and I went to the sites in the weeks after the bioblitz. Northern wood crickets no longer occur there. I believe the records are correct, but that the crickets have gone extinct in those places. Northern wood crickets are reported to be sensitive to forest fragmentation, perhaps especially so in the northern fringe of their range, and such fragmentation clearly took place where they once were found in Lake and Marshall counties. I will continue to check the region’s larger surviving forest blocks, but it seems likely that the species no longer occurs in northern Indiana.

Incidentally, the other expected early-season singing insect, the green-striped grasshopper, lives in Eagle Creek Park’s meadows and prairie areas.

Next year’s bioblitz is expected to take place in one of my counties, and I am looking forward to the experience.

 

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