The Varroa mite (Varroa jacobsoni ) is an external parasite of honey bees. It was first discovered in the U.S. in 1987. Previous to this discovery the mite had not been found in the U.S., although it had been a major problem in Europe, Asia and South America. The Varroa mite is a small, red brown mite measuring approximately 1 - 1.5 millimeters in length and width. The mites feed on the blood of adult bees, larvae and pupae. The feeding of Varroa mites has a number of effects on the bee, from damaging tissue to shortening the bee's lifespan as an adult. In addition, the mites vector disease viruses. Heavy levels of parasitism increase bee mortality and weaken colonies. Colony mortality varies from a few per cent the first year to levels approaching 100% by the fourth or fifth year.