by Carl Strang
Of the several species of singing insects that have been expanding their range northward, the jumping bush cricket is the one whose northern boundary has not yet extended beyond DuPage County. Each year I have sought out their north point, and each year it has moved. This year is no exception, and in fact their repetitive burry chirps soon will be heard in north Cook County if the trend continues.
The crickets seem to use our north-south streams as travel corridors, and so I took an evening to scout for them along the Fox River, in Kane County just east of DuPage. I heard none on either side of the river from my starting point in North Aurora to the turn in Geneva, though the habitat looks very good. My hypothesis from this is that they spread from Indiana via the Kankakee River to the Des Plaines/Illinois River, and reached DuPage County via Salt Creek and the branches of the DuPage River. The Fox meets the Illinois well to the west, and so additional years will be needed for the crickets to reach central Kane County, either via the Fox or by spreading westward from the West Branch of the DuPage River.
Incidentally, I have tested an idea I had last year, and so far it seems to be working. The jumping bush cricket’s song is loud enough to be heard easily from the car on a driving survey. Seeing one is difficult, however. I have found that they are singing from perches on tree trunks, especially from small shelters in the bark, and the reflecting foliage layers around them confound the source. Looking up the trunk for the lifted, vibrating wings, often leads to success. Another student of singing insects, Lisa Rainsong, has reported in her excellent blog that in her yard in the Cleveland area, they are difficult to find for another reason: they are very active, shifting locations between songs.