Q: What’s going on with my wax myrtle? There seems to be some kind of infestation on the stems.
A: It’s not an infestation, it’s wax myrtle sex! The things on the branches are female catkins (flowers) which will get pollen from male catkins (flowers) on a nearby shrub.
Wax myrtles, like most hollies, are dioecious: some plants bear flowers that produce pollen and others bear flowers that accept pollen and make seeds.
Birds love wax myrtle berries and they love making nests in the dense shrub so you have done a good thing for wildlife in your landscape!