According to a rule followed by many entomologists (if not by dictionaries or journalists), 'house fly' is 2 words but 'butterfly' is 1. Per the same rule, is it honeybee or honey bee? ladybug or lady bug? dragonfly or dragon fly? stinkbug or stink bug? (Four answers required.)
HONEY BEE, LADYBUG, DRAGONFLY, STINK BUG (2 words if 2nd part accurately describes the category it belongs to)