Blue Grabbing Ghosts are sub specie ghost in Luigi's Mansion. They are a sub specie of the Grey Grabbing Ghost. They have 20 HP and are able to deal damage to Luigi unlike the Grey Grabbers. They are only found in one room of the mansion. They can deal a large amount of damage if Luigi doesn't shake them off in a small time. They do about 2 hearts of damage for every second on Luigi. They are invisible to Luigi, similar to Purple Grabbers.
Locations
They are only found inside the Mirror Room. Since they are invisible to Luigi, you need to use the mirror to locate and vacuum them. There are about 5 of them in there.