Those eggs are deposited in the tree's branches, but when they hatch (which they do two weeks after being laid), the resulting larvae falltotheground and tunnel downtothe tree's roots, from which they suck their sustenance.
Even the Bush administration has reportedly begun contingency planning to start a draw-down this fall irrespective of the circumstances on theground in response to an expected domestic political imperative demanding what is euphemistically called a "new strategy" come September.