Xenomorph Drone

Drones are the "worker bees" of an Alien hive and are loyal servants to the Xenomorph Queen. They are responsible for collecting hosts, further building the hive, and caring for the Queen's eggs.

Appearance
Drones are one of the smaller Xenomorph types. Runners are a bit smaller than them by three inches or sometimes seven inches when they stand upright. They are primarily black, sometimes grey with smooth domes.

Drones have been known to sometimes appear with a slight hint of brown but mostly can come in black, and since Warriors can be brown but not often and are stronger than a drone, this could mean that particular Drone is somewhere between a Warrior and a Drone or they are simply stronger than their other siblings.

Mannerism and Abilities
In the game Alien vs. Predator: Extinction they can spit acid in a similar but less destructive way than a Praetorian. Their tails are merely barbs and they use their claws in battle as opposed to their tails, the complete opposite of the blade-tailed Warrior Xenomorph.

Drones are more calm Xenomorphs, able to plan and would rather sneak attack an enemy than run into the line of fire and face them head on.

They are one of the most common Xenomorph, even more so than the Warrior. When the Hives main defense of Hive Warriors and Normal Warriors have been killed, Drones will fill their places as the main defense.

Evolution
Drones are capable of evolving into Praetorians by releasing certain pheremones that cause the others to frenzy and attack. If the drone under fire can defend itself long enough and escape with its life, it will molt in a Praetorian. However, because of the Drones' relative weakness to the other castes, it is very uncommon they survive making the Praetorian a very uncommon variety of alien.

Facts

 * According to H.R. Giger, all Drones are genderless, but this is debatable.
 * A Warrior can have a smooth and ridged dome but a Drone can only have a smooth dome.
 * Drones when having cornered prey show some sadistic tendencies (time willing), an example when the Drone on the Nostromo in Alien cornered Lambert it seemed to enjoy every moment of her fear (It is implied that the Alien sodomized Lambert with its Tail, though it is questionable). This is also seen when right before it head bites Parker, taking its time and possibly enjoying every moment of his fear.
 * The Runner in Alien³ was technically a drone, due to its smooth dome. Nearly all fans tend to separate the two however.