If you don't remove them though, don't they multiply up to 3 times faster in drone larva than worker larva? What I'm thinking is less drone larva, less opportunity for them to multiply as fast... not to mention that the bees wouldn't be wasting quite as much resources raising drones either... ok it's not much, but it adds up over time. But mostly I'm thinking the smaller worker cells don't offer as much opportunity for the varroa to multiply.