The Skrawn were a race of giant insects originally from the planet Kolox.
Biology
The Skrawn were armed with a particularly lethal sting. One scratch was enough to cause anaphylactic shock in its victims. A sting would produce a long painful death. The Skrawns' highly developed sense of smell was capable of detecting time travellers such as the Doctor. (COMIC: The Skrawn Inheritance)
Technology
Skrawn ships were organic constructs, grown from cellular electron amoeba and capable of carrying Skrawn hives. Although able to travel through the Kolox Nebula, they were not designed to be able to navigate the time winds. (COMIC: The Skrawn Inheritance)
History
Bitter as a result of their home world's destruction in the Time War, the Skrawn were driven by a desire to avenge their planet and rid the universe of “human filth”.
In the 59th century, the Skrawn attempted to steal the time-navigation unit from the Tritanic to recreate their planet. They were able to find and steal it and later used it to find the the Doctor's TARDIS, but were followed by the Tenth Doctor and Martha Jones. They were able to stun the Skrawn and steal back the time-navigation unit, leaving the Skrawn lost in the nebula. (COMIC: The Skrawn Inheritance)