Azalea lace bug. This is a sucking insect that causes the stippling or dotting of the foliage.....heavy infestations can result in almost white leaves.

Insecticidal soap will work for early light infestation when the nymphs are present. At this time of year, Neem or horticultural oil is your best approach.

jtwarren, that you are actually losing azaleas to very heavy lacebug infestations tells me that your plants aren't happy. The usual issue is too much sun when it comes to azaleas and these particular pests, but it could be anything.

The lacebugs hang out under the leaves and that is where you need to direct your spray.

Where in the world are you?

What are the growing conditions these have?

Soil, type and pH?

Amount of sunlight?