Last month on my neighbor’s window frame I spotted these flat, oval eggs. After a little searching, it looks like they are katydid eggs, probably laid by a Greater Angle-winged Katydid (Microcentrum rhombifolium). Katydids typically lay their eggs in rows on the stems of plants, but evidently window frames will do in a pinch.
I suspect these will hatch next spring, although at least some (like the second from the bottom on the left-hand row) may have been predated or parasitized. Alas, I don’t have any photographs of M. rhombifolium, so here’s a picture of a much smaller katydid species from a different subfamily, a lesser meadow katydid (Conocephalus sp., I believe):
Katydids (family Tettigoniidae) are sometimes called long-horned grasshoppers for their long antennae (especially long among meadow katydids like this one), although they are more closely related to crickets (family Gryllidae). Many are pretty remarkable leaf mimics.