This is a red maple. It is always covered with wasps. They leave a black...
This is a red maple. It is always covered with wasps. They leave a black powdery subastance on the leaves and the bark. The bark has little round raised spots. Is this tree going to survive, and how do I elimanate the insect problem. We have already treated the tree systemically - with no results (3 different times).
The wasps are just innocent bystanders to your tree's problem. Your maple has a scale infestation. Scales are insects that hide under a cover, like a turtle shell, and suck nutrients out of a plant.They are the little round bumps you described.
There are several species of scale that will infest maple trees. Some excrete a very sugary substance known as "honeydew". This falls onto the leaves and bark below and a type of mold, known as sooty mold, grows on the sticky sweet honeydew. Sooty mold is black and is what is giving your tree it's black appearance. (Honeydew is also attractive to wasps, and that's why you are seeing wasps hovering and feeding.)
Unfortunately, the scale on the bark in the photo is not in focus so we cannot see what kind of scale your tree has. Please send us another photo (or 2 or 3) showing a close up of the scale and we will be able to recommend a product to control it.