He had orange skin, light blue eyes, dark red hair, and a five foot long prehensile tail, During the course of the novel he dyed his hair blue.
Newter also has a tattoo that looks like: "the greek ‘Omega’ symbol, but upside down. Maybe a stylized ‘u’which is "just above his heart"
He is able to leap in excess of 15 feet exceedingly fast (it is said that it takes the same time for him to leap from one opponent to another as it takes Skitter to throw a punch).
He appears to moves in a half-run half-crawl manner which allows him to move faster than the average person (was easily able to keep up with Brutus when he was larger than a horse).
Additionally, any of his bodily fluids (including sweat) contained powerful hallucinogens which can "send someone off to la-la land" in "only a few seconds". When Newter brushed against some of Skitter's bugs they "dropped off the wall or out of the sky, falling to the ground, alive but stunned." Skitter indicates in this same passage that several of the people that Newter were fighting were removed from the fight before he even touched them leading her to believe that he hit them with either "blood" or "spit".
Additionally, his ability to move vertically appears to be exponentially better than the average person as at one point "he darted up the side of the building and slipped into an open window like a bolt of greased lightning" assumedly indicating that he has some form of enhanced ability to grip objects (wall-crawling).