The real unit is the colony, which is an incredible example of emergent order. There's this set of forces that link these creatures together in ways that are not controlled. So getting back to the logistics, what crops are important, demanders of honey bee services? The first one that people mention are almonds because almonds are the most valuable agricultural product of the state of California.
Wally Thurman of North Carolina State University and PERC talks with EconTalk host Russ Roberts about the world of bees, beekeepers, and the market for pollination. Thurman describes how farmers hire beekeepers to pollinate their crops and how that market keeps improving crop yields and producing honey. Thurman then discusses how beekeepers have responded to Colony Collapse Disorder--a not fully understood phenomenon where colonies disband, dramatically reducing the number of bees. The discussion closes with the history of bee pollination as an example of a reciprocal externality and how Coase's insight helps understand how the pollination market works.