More than 100 cops will search a weed-filled area along the Brooklyn-Queens border today in search of a missing 7-year-old boy, police sources said.

Authorities are baffled by the disappearance of Patrick Alford, who hasn’t been seen since he vanished from his foster family’s East New York home on the night of Jan. 22.

Police dogs lost Patrick’s scent at a bus stop two blocks away.

Detectives first eyed Patrick’s birth mother in the disappearance, but now believe she wasn’t responsible.