Question
We have a green (I think varigated) maple tree.  The foliage is very dense.  I notice that yellow jackets and wasps are attracted to this tree.  We are unable to find a nest in the tree or anywhere else on our property.  What do you think may be attracting the yellow jackets to the tree?

Answer
Sounds like the tree has one of the sucking type insects. These suck the plant juices from the leaves and/or twigs and secrete a substance called Honeydew which is high in sugar content and sticky. The wasps are collecting the honeydew. I would treat the tree with an insecticide called Bayer Tree and Shrub Insect control. This is applied to the soil around the tree and the roots will transport the insecticide to the leaves and twigs killing the insects that suck the plant juices. When the honeydew is gone the wasps will leave. Check with your local nursery fro this product. Here is a web link to this product.

http://www.bayeradvanced.com/product/Tree-Shrub-Insect-Control/concentrate.html