What are these red scaly bumps on my willow bushes?
The red/pink structures appear to be willow leaf galls, caused by an eriophyid mite. They will not harm the plant and no action is needed.
The galls are caused by eriophyid mite feeding or egg laying hormones, which stimulate the plant tissue to develop into these structures. The structure then serves as shelter, protection and food for the developing mites laid within.
Here's a great publication on the topic of eriophyid mites from Utah State University:https://extension.usu.edu/files/publications/factsheet/eriophyid-mites2010.pdf