These "cyber bugs" are actually a secret, experimental weapon (built by the United States, if I recall correctly...), but one turned against mankind by those Mysteron scoundrels.. Once aboard Skybase, the creepy little bugs start multiplying and breeding (with yucky egg sacs), until Destiny and Captain Scarlet at last find a way to destroy them. "It's time to wash these bugs down the drain," Scarlet notes, after realizing that water is the bugs' one weakness. Meanwhile, Lt. Green gets more than she bargained for when she is cocooned by the bugs and they start to scan her mind for detailed information about the layout of Skybase (which leads them to the atomic reactor...).
Watching this episode of Captain Scarlet, which I enjoyed even more than the two-part pilot, I felt the warm and happy glow of nostalgia. Not so much for Captain Scarlet or the other supermarionation shows, but for the mod-1960s live-action epic, UFO...which I still love (flaws and all). "Swarm" felt very much like an episode of that series, only modulated with the latest CG effects to be more dramatic. The narrative is familiar, however: an alien plot to subvert mankind's last line of defense.
And hey -- wasn't someone going to remake UFO a couple of years ago? I think it would be a cool idea, but - to get off topic - I'd miss the series' (now misplaced...) sense of futurism, the feeling that the 1980s would be a glorious extension of the freewheeling late 1960s (including a mod, flamboyant sense of fashion, an optimism about space travel; casual sex, and lots and lots of drinking...). The new Captain Scarlet, made in our lugubrious, conservative 21st century (the era of the PG-13 horror film...), doesn't reflect any of that wonderful old Anderson stuff, but the stories, characters and technology do indeed feel familiar...and charming. If only the late Ed Bishop were around to give voice to Captain Scarlet.
Now that would be cool.