The size of the alveoli and, therefore, their number per square decimeter varies significantly from one race of bee to another. The average alveolus size in European breeds is between 0.20 inches (5.13 mm) (Apis mellifica ligustica) and 0.26 inches (5.5 mm) (Apis mellifica carnica). Apis mellifica lies roughly between the two, with an average size of 0.21 inches (5.37 mm) or 800 cells/dm² (875 for ligustica and 760 for carnica). Alveoli are usually smaller in African bees. At first, the virgin wax is white and then browns until becoming almost black under the effect of pigments that are deposited on the combs.