Until 1851, beekeepers harvested honey and beeswax by killing the colonies inhabiting the hives. In that year the American apiarist Lorenzo Lorraine Langstroth discovered the principles of "bee space". Bees leave spaces of about 0.6 cm between wax combs. In artificial hives, if this space is left between adjacent comb frames and between the end frames and the walls of the hive, each comb will remain unattached to neighbouring combs. Langstroth's discovery made it possible to remove individual frames from a beehive and to harvest honey and wax without destroying the colony. It also became possible to control disease and to maintain a larger number of colonies.