Question
I have a willow on my yard that is 50 years old,about 100 ft tall and 6ft wide. The past 10yrs I have never had these small black beetles. They are all over the tree and everywhere underneath it, including in my grass. How do I possibly get rid of this issue with a tree this big?

Answer
Sounds like willow flea beetles. Spray the foliage with an insecticide. Garden insecticides containing carbaryl (Sevin), spinosad, bifenthrin and permethrin can provide fairly good control  These are contact insecticides and you may have to spray a couple of times about a week apart to make sure you cover all the beetles present.
They will not kill the tree unless there is several years of complete defoliation.  

Check with your local nursery/garden type store for an insecticide for flea beetles.