Species

There are about 20,000 species of bees worldwide. Some species may not yet have been discovered, and many are either not named or have not been well studied. Bees are found throughout the world except at the highest altitudes, in polar regions, and on some small oceanic islands. 

The greatest diversity of bee species is found in warm, arid or semiarid areas, especially in the American Southwest and Mexico. Bees range in size from tiny species only 2 mm in length to rather large insects up to 4 cm long. Many bees are black or gray, but others are bright yellow, red, or metallic green or blue.