Nice deduction skills... I curse them daily, as go thru and flush them off my plants, or crush the occasional slow one, they're really fun I try not to marvel at them, but are sucking the life from your plants, and possibly infecting them with any number of pathogens they can carry.
I can't confirm it but I've found dead leaves at the end of healthy stalks on my colocasia, and I'm pretty sure that these buggers are to blame, I could be wrong about that.