The largest bee in the world is Wallace’s Giant Bee (Megachile pluto*). The females are larger than the males, and grow up to 3.9 cm (1.5″) long with a wingspan of 6.3 cm (2.5″). According to Wikipedia, it was discovered in 1858 by Alfred Russell Wallace (one of the great explorers/scientists best known for independently discovering natural selection at around the same time as Darwin) and was thought to be extinct until it was rediscovered in Indonesia in 1981 by Adam C. Messer. Megachile pluto is an example of one of the species that depends on termite mounds for nesting habitat, of which there are many.
They look like this:
The smallest bee in the world is Perdita minima. This species of solitary bee is isolated to the southwestern United States, and is less than 2 mm (<0.08 in). That means that the largest bee is almost twenty times bigger than the smallest bee!
There is also this extremely interesting image, comparing the little Perdita to a Xylocopa species (carpenter bees). While they are not the largest bee in the world (see above), they are the largest bee species in the United States.
(For all of you primates out there, we can translate this difference into the difference between the tallest human ever (as we are the tallest primates, and capable of being rather the heaviest as well), who was 2.72 m (8 ft 11 in) and the smallest primate, the Phillipine Tarsier (Tarsius syrichta), which is only 85-160 mm (3.35-6.30 in). That means that the tallest primate was 32 times longer than the shortest primate. This comparison is a little disingenuous, as Primate is an order, while “bee” is a superfamily, but the taxonomic diversity of bees is much higher (~25,000 species compared to about 350), so they are hard to directly compare.)
But who cares about primates?!?! (*yawn*)
Let’s compare bee sizes!
*Ironically, given that Pluto was our smallest planet**
**When I was your age, Pluto was a planet!!