Don't introduce it, just use it. But do make sure the context provides additional information.
For example:
A high-pitched squeal shattered the silence.
Jon leapt to his feet, reaching for the pulse-rifle leaned in the corner. Two long strides brought him to the window, where he carefully slid the shutter open just enough to peak out.
"Sturbok!" He put back the pulse-rifle and opened a cabinet near the back of the room. "Everybody up. On the double. Sturbok swarm."
The bunkroom door swung open and a stream of sleepy-eyed youths stumbled out. As each passed, he handed them a mesh hood and a six-foot bamboo pole.
Now, assuming I accomplished what I was trying to, you don't know everything about a Sturbok yet, but you do know several things: You know it's probably a living creature, or possibly an autonomous robot. You know they travel in swarms. You know a Sturbok swarm needs to be dealt with, but it's more of a nuisance than a danger; it's not whatever danger Jon was initially alert for. You know a mesh hood probably provides protection against them. You're wondering what the bamboo poles are for, though. (So am I.
)
If I wrote the rest of the scene, I'd work in more details about the Sturbok. You'd find out what they look like, and what it is they do that creates a problem.