First and Last Song Dates

by Carl Strang

For five years, now, I have noted the first and last dates on which I hear each singing insect species. This allows me to look at the phenology of the singing insects as a whole. Was 2010 early or late, compared to the others? Here is what I found: 11 species with the earliest song dates in 5 years, 12 with second-earliest, 2 with third-earliest, 2 with fourth-earliest, and 2 with fifth-earliest. This distribution seems to indicate an early season for starting dates, and indeed it departs from the expected even distribution when I apply a chi-squared test (χ2 = 18.76, p < 0.01).

In northeast Illinois, the first singing insect to begin its display is the green-striped grasshopper. Its earliest crepitating song flights can be heard in April or May.

The distribution of last observed song dates was more even among years, though possibly suggesting a shift forward consistent with their early start: 3 species with latest song dates, 4 with second-latest, 5 with third-latest, 8 with fourth-latest, and 7 with fifth-latest. The difference from an even distribution was not statistically significant, however (χ2 = 3.11, p > 0.01).

The three common species of ground crickets consistently close out the season, their songs continuing into November.

Looking at the snow outside, I know I have a 3-4-month wait until the next singing insect season begins.


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