Link to my question on how do Starweirds survive the vacuum of space and enter ships in hyperspace?
According to the various sources I’ve read, the Starweirds seek out and kill force-sensitives first, then anything else left alive is killed. They seem to survive the vacuum of space and hyperspace, as well as being invulnerable to conventional weapons (blasters, slugthrowers, melee, etc).
According to Wookieepedia,
The species' incorporeal nature made it possible for the creature to resist conventional attacks and pass through solid objects, although force fields still stopped the creatures.