Re: My mostly hard sci-fi campaign
Found one paper of a direct imaging survey of the area around L4 & L5. They didn't find anything. Their limits are such that this means nothing 175 meters in diameter or larger if it's S-type, that is, silicaceous rock-type stuff, or 350 meters or larger if it's C-type (carbonaceous, a type of primitive rock we don't have on earth any more). C-type is substantially darker, so the limit on brightness means more "room" for a dark thing to remain undetected.
Heh. Only marginally related, but this looks interesting; it's from a forecast of the next fifty years, made in 1986.
EDIT:
That's talking about Jupiter's Trojans, not Earth's. That's from a more powerful survey than the one I found mentioned above looking for Earth-Trojans.