An apiarist is a beekeeper. In period, these people were craftsmen, although there weren't as many of them as say carpenters or butchers. They were the source of wax (used for hardening leather, making candles, sealing letters, jewellery making) and honey (natural sweetener, also used in mead).
Apiarists would often maintain many hives. Hives, known as skeps, were made of woven straw in a large cup shape, and could hold about 18 litres. No more than 40 were recommended to be held on a quarter acre of land.
An interesting article regarding beekeeping in period is by Edmund Southerne, "A treatise concerning the right use and ordering of bees", 1593.
The patron saint for beekeeping may be one of the St Bartholomews. The bee->honey->mead->much joy association was one of the major reasons behind the choice of names for the SCA College of St Bartholomew.
Also see essays