Why the peony may have evolved to cover the bud with the waxy coating?

Here is the answer I received from a previous TA. But it doesn't make any sence to me as it talks about scale and not Peony.

'Scale insects are the most common insects on plants. They usually go unnoticed until considerable damage has been done and a large population has developed. Many of them have several generations a year. They injure by sucking vital juices from the plant. Peony scale is found on the stems and branches of camellias (and azaleas). They are hard to recognize as they camouflage themselves well. The hard shell which covers their body is blended to match the color of the stems.

Scale insects vary considerably in appearance. They may be circular, oval, elliptical to oyster-shell shaped and even linear and rectangular. Some are flattened and others elevated, resembling a tortoise shell. Colors range from white to black, but grays and browns predominate. Most species are from 1/16 to 1/8 inch in diameter. Some kinds of scales infest the leaves of plants, while others are found both on stems and leaves, and still others are attached chiefly to the stems. Because of their waxy covering, scales are less affected by variations in weather or natural enemies.'

My question remains: how has the peony plant evloved to cover the bud with the waxy coating meaning how did it come to become this way? Why and how the evolution from a non-waxy coating (if this ever existed) to a waxy coating take place?