Infected pupae fail to survive, or may be born with deformed wings. Eventually, the mite population increases to a point where all the bees in the beehive die. This can take up to three years from the original infestation. The mite spreads naturally from hive to hive by bee contact. However, the rapid spread of the mite worldwide is due to human activities.
Modern beekeepers shift their hives long distances to pollinate crops, or gather honey.
This enabled the Varroa mite to spread over the whole North American continent within five years of being introduced. Some European countries, which have strictly controlled the movement of bees, have managed to greatly slow the spread of Varroa. Another means of spread is the international trade in live bees. Queen bees are shipped worldwide, and are believed to be responsible for the spread of the mite from Europe to both North and South America. New Zealand has prohibited the import of live bees for the last 40 years to protect our bee health status.