Skithra

The Skithra were a species of scorpion-like beings.

Biology
At least one individual, the Queen of the Skithra, had a partly humanoid appearance. As a hive species, if the Queen was destroyed, then the rest would also die.

The Skithra were able to fire an energy resembling electricity from their stingers. This energy would appear green when charging and would turn red when it was about to be fired. (TV: Nikola Tesla's Night of Terror)

Technology
The Skithra were scavengers who believed that they were superior to other races, and therefore entitled to their technology. They would steal the technology of other races and use it for themselves rather than building their own. Races that the Skithra have stolen from include the Silurians, Thassor, Venusians, Klendov, and Dullirians. When the stolen technology started to break down, they would kidnap an engineer of another species and force them to repair it, regardless of whether or not they or their species were familiar with the technology. If the engineer could not repair the broken technology or refused to do so, the Skithra would kill them.

The Skithra had also at some point stolen technology which allowed them to appear human. This technology even allowed them to disguise themselves as specific individuals, and did not require the individual to be kept alive in order to keep their appearance. When disguised as humans, their eyes appeared red and the energy which came from their stingers appeared to come from their hands. (TV: Nikola Tesla's Night of Terror)

History
In 1903, the Skithra Queen threatened the Earth with a stolen Venusian spaceship with a Klendov warp drive and a Dullirian resonator. At some point, they stole a Silurian blaster, presumably from one of the underground settlements the species hibernate in, which they used in an attempt to kidnap Nikola Tesla. (TV: Nikola Tesla's Night of Terror)

At some point, one Skithra was imprisoned in the same Judoon prison as the Thirteenth Doctor. (TV: Revolution of the Daleks)