For the past forty years there have been virtually no introductions of honeybee stock from foreign countries into Canada or the United States. This has been due to the stringent restrictions on importing honeybees which have been in force since 1922, as a safeguard against the introduction of acarine disease. The mite which is responsible for the disease, Acarapis woodi, is present in many parts of Europe, and has also been reported from Asia, Africa and South America. It has not so far been found in North America, although external mites of the same genus (A. dorsalis and A. externus) are now known to occur fairly commonly throughout Canada and the United States.