The Drevak is a type of demon frequently used as spies or messengers. Drevaks are weak and blind and thus do their tracking by smell.
Drevaks are pest-like, resembling giant maggots with their smooth, white, and larval flesh. Despite their less than intimidating appearance, Drevaks are dangerous. Though their shapelessness renders them unable to fight, they use the poisonous black spines in their mouth to sting and poison their targets. Their venomous needles, once broken and stuck onto the skin of a victim, is incredibly painful but fairly easy to treat.
Drevaks are unintelligent, have needle-tipped hands, make chittering sounds, and smell like rotting garbage. They also move, though in a lurching motion, incredibly fast. Drevaks are said to roam in packs.
In 2007, Drevak demons were employed by Valentine Morgenstern to spy on his former parabatai Lucian. The Drevak demons were lurking on his lawn and had attacked Maia, who was alerted by their presence because of their smell. Luke then arrived and ran one over with his pickup truck. The other one, however, was able to report back to Valentine and told him of the young werewolf, Maia.
There were also Drevak demons, including the one at Luke's, on Valentine's ship, all of which Jace terminated with ease. One in particular turned just in time to be drenched in the face with Ravener poison from its exploding sac and soon "died" and disappeared.