In early May of this year, iNaturalist user 'human_landfill' posted this image of a ground cricket nymph. When I first saw the image, I was perplexed as its markings looked like no native NY ground cricket species I was familiar with - and, it was already a mid-sized nymph (all native ground crickets in this area would either still be eggs or maybe tiny 1st instar nymphs this early in May). Then I realized it looked a LOT like the common European species Nemobius sylvestris - not previously known to occur in North America. Digging back into the iNaturalist photos, I discovered this image from nearby that appeared to be an adult female of the species - seemingly corroborating my suspicions.

I had the opportunity to visit the site of the more recent photo a few days ago, and found good-sized nymphs to be numerous in an area of extensive leaf litter within the park - mostly surrounded by European plants such as Vinca, Hedera helix, etc. I will be attempting to rear them in order to confirm my ID, but these nymphs are clearly not any of the NY native species, and their markings match up pretty perfectly with photos of European nymphs. For what it's worth, their behavior is also quite different - rather sluggish compared to native ground crickets. The habitat, which is suburban and filled with many European imports, also makes sense as a place for such a species to become established. Another common European orthopteran, Leptophyes punctatissima, is already known to be established in this area.

How long this species has actually been present in the Rochester area remains to be determined.

female nymph from same locale