The Varroa mite is a parasite that needs the bee colony for its entire life cycle. Outside the hives, the parasite only survives for a short time, up to one day. The mite feeds on the bee essentially on the fat body and other body fluids and prefers young nurse bees that care inside the hive for their queen bee, brood, drones and foraging sisters. This part of the parasite life cycle is called the dispersal or formerly the phoretic phase.
If the hive is strong and there is no hibernation period, then it is possible that the parasite will not kill the colony.
BUT: the production efficiency of the bees decreases because they have to deal with a rather big disruptive factor – Imagine – You would be bitten in your abdomen or back by an evil mole-sized creature all day long!! Could you be productive?
More mites – less honey
Next, the mite needs the bees as a means of transportation onto the frame to find the exact brood cell to invade and successfully reproduce. This infestation of the bee brood is therefore the reproductive phase of the mite and more dangerous for the bee colony, because the parasite harms the brood by feeding on it and – worse – it can act as a vector and transmit virus diseases.
When the colony is productive – foraging and producing honey – the colony has a lot of brood cell and 75 % of the mites are inside the cells!
So, as bees are very sensible to chemical treatments – in a way that they do not tolerate much toxics – and also we don´t want residuals in our honey – the best way to control the mite infestation is the use of powerful plants.