Apis dorsata laboriosa, the Himalayan honey bee, is the world’s largest honey bee; single adults can measure up to 3.0 cm (1.2 in) in length. Before 1980, Apis dorsata laboriosa was considered to be a subspecies of the widespread Apis dorsata, the giant honey bee, but in 1980 and for almost 20 years thereafter it was elevated to the rank of a separate species. It is now classified once again as a subspecies of Apis dorsata (Engel, 1999). It is highly adapted to its highland habitat in behavior and there has evidently been little gene flow between it and lowland A. dorsata for millions of years; some consider this evidence that it should be classified as a species (Arias & Sheppard 2005).