Here's a playable stat bock for a Space Bug Drone:
[text]
ST: 14 HP: 15 Speed: 6
DX: 12 Will: 5 Move: 6
IQ: 5 Per: 5
HT: 12 FP: 12 SM: 0
Dodge: 12 Parry: 6 DR: 6
Bite (12): 1d+1 impaling, Reach C.
Claw (12): 1d+1 (2) cutting, Reach C.
Tail (12): 1d (2) impaling, Reach 1.
Traits: traits.
Skills: skills.
Notes: notes.
Will worry about details later, but this is at least a starting point to throw into playtest. Omittting acid blood for now, but it may get thrown in later. It's a big part of the xenomorph, but since I'm keeping this generic-ish, I can always just throw it in as a template mod too (yay GURPS!). I just picked a number for DR--in Aliens, they seem to shrug off pistol fire (usually), but the Pulse Rifles (usually) blow them up.
I should probably add something here.