Diuturnity's Dawn. Book Three of the Founding of the Commonwealth

In nearly two dozen novels about the Humanx Commonwealth, Alan Dean Foster has fascinated readers with his brilliantly imagined interstellar realm-where humans, thranx, AAnn, and other species strive to work together to put the common good above selfish ends. But renewed efforts at cooperation prove that familiarity breeds contempt. Diuturnity's Dawn is the third thrilling novel in The Founding of the Commonwealth, a spectacular space adventure that traces the perilous early years of this remarkable universe.
From the beginning, while sharing the Orion Arm of the galaxy, contact between humankind and the thranx has been tenuous at best. Yet nearly a century after first contact, the likelihood of closer human/thranx relations is as far away as ever. Humans still find these insectlike beings physically repulsive, a distaste the thranx return in kind. At times the cordial veneer barely conceals the suspicion and distrust boiling just below the surface.
Yet idealists on both sides refuse to surrender their dreams of achieving a thranx/human alliance. Among the most dedicated are a minor diplomat named Fanielle Anjou and her thranx counterpart. Others intend to make sure such a liaison never comes to pass .