Vermin
"No doubt about it¸" the exterminator said matter-of-factly; "You've got yourselves an infestation of Blattella asterii."
"Star roaches¸" the Colonel hissed¸ making no effort to hide his disgust. "How bad?"
The exterminator looked around as though he could see the creatures through the ship's bulkheads. "Pretty extensive here around your cargo bay. Probably how they got in. You're looking at six thousand credits. That includes chemical and bioengineered pesticide. Nanites are extra."
The Colonel silently mouthed a curse. I couldn't believe my ears. Six thousand credits! Over a quarter of the money we'd made off that last job.
The Colonel sighed a long sigh of defeat. "Fine. Go ahead and get started. Let Bel here know whatever you need from us."
Every world with living organisms has its share of lifeforms harmful to crops and livestock¸ and generally viewed as economic and ecological burdens. Vermin (colloquially called) tend to survive even in the face of intensive efforts to destroy them and thrive under conditions often harmful to sophonts. They follow sophonts out into the galaxy¸ stowing away (deliberately or accidentally) in space vessels and spreading their numbers anywhere their hosts go. There are literally millions of lifeforms that can be considered pests. Under the right conditions (plentiful food¸ lack of predation¸ etc.)¸ even animals normally considered harmless can become pests.
This supplement for Cepheus Engine and the Original Science Fiction Roleplaying Game takes a brief look at infestations of starships by vermin and their effects on the crews therein. It also offers a look at some common pests and a method for running an infestation.