Megachile pluto

Megachile pluto is a very large Indonesian resin bee (a leafcutter bee that uses resin to make compartments in its nest). As females can be as large as 39 mm (1.5") long with a wingspan of 63 mm (2.5"), Megachile pluto is regarded as the largest bee in the world. Males only grow to about 23 mm (0.9") long.

Megachile pluto was first discovered in Indonesia in 1859 by the naturalist Alfred Russel Wallace. It was thought to be extinct until it was rediscovered in 1981 by an American biologist, who found six nests on the island of Bacan and other nearby islands.

Megachile pluto build their nests inside active termite nests, which explains why even island residents were unaware of the bee's existence.

Reference
Messer, A. C. 1984. Chalicodoma pluto: the world's largest bee rediscovered living communally in termite nests (Hymenoptera: Megachilidae). '' J. Kans. Entomol. Soc.'' 57: 165-168.

Megachile pluto