What is Varroa mite? Varroa destructor is a tiny mite (like a tick) that infests honey bee colonies. It is about the size of a pin head and feeds on the haemolymph (insect blood) of both adults and developing bees. This quickly weakens the individuals. Also, as with all ‘sucking’ insects, viruses are transferred between the host (the bee) and its parasite (the mite). One of the viruses that the bees suffer from is known as “deformed wing virus”.
This disease most seriously affects the colony because it is the developing bees that are affected. The adult Varroa mite hides inside the brood (nursery) cell and feeds on the haemolymph of the immature bee. When she reaches maturity and emerge from her cell, her wings are shrunken and useless. This bee is able to perform in–hive tasks such as brood care, cleaning, receival and dehydration of nectar and wax production. However, once the bee is about three weeks old it's time for her to become a forager. Bees suffering from deformed wing virus have non–functioning wings and are unable to fly, so they cannot forage.
The deformed wing virus has been present in colonies around the world for many years, but at very low levels (~ 10%). However, in the presence of Varroa mite, the number of emerging bees affected by the virus can be as high as 90%. This means that up to 90% of the bees within a colony may never fly, therefore, they will never forage, and the colony will slowly starve to death.
At this time, Australia is the only country that does not have Varroa mite. This is why we still enjoy the free pollination services of natural–living, or ‘feral’, honey bees. It is of great importance that we keep this pest from our shores.
For more detailed information about this honey bee pest visit:The Conversation on Varroa