Why were honey bees at one time called white man's flies?

Although there was a large number of bee species in the Americas before the European settlers arrived, none of them were what we now recognize as honey bees. When the settlers arrived, they brought their honey bees with them to pollinate the European seeds and saplings they had also brought. Without them the grasslands would not have been covered with the clover the imported livestock ate.
It wasn't long before the Native Americans realized that seeing the honey bee presaged death and destruction for them and their way of life -- and they came to refer to the bee as the 'white man's fly'.