As part of the river clean-up at the Arakawa, we had a biologist explain things to us. Such as, there are 2,000 raccoons in Tokyo (nothing compared to Toronto's 50,000, but I doubt anyone's complaining). The biologist told us that we'd be able to find plenty of "eggs". I guess these are the ones he had in mind. If you're puzzled by what you're seeing, it's a mantis hanging upside down and planting the eggs in a nasty sticky mess. I have no idea how the biologist managed to spot this!