Megachile pluto is a very large Indonesian resin bee (a leafcutter bee that uses resin to make compartments in its nest). Females can be as large as 38 mm (1.5") long with a wingspan of 63,5 mm (2.5"), Megachile pluto is regarded as the largest bee in the world, and has been referred to as Wallace's giant bee. Males only grow to about 23 mm (0.9") long. Megachile pluto was first discovered in Indonesia in 1858 by the naturalist Alfred Russel Wallace.