A couple of weeks ago I took a picture of a bald faced hornet feeding on some sort of white fungus. It turns out I was entirely wrong and it wasn't a fungus at all. It was a colony of the woolly alder aphids (Prociphilus tessellatus ) feeding on a speckled alder. Above is another picture of them. The colony is almost entirely gone now but I inspected the remaining pieces to see the actual aphids. The white fluff is a waxy material that protects the aphids from predators. What was attracting all the attention from the wasps and the hornets was probably honeydew.