Zeb refers to the small shelled creatures as bogans. As well as being the dark side of the force in George Lucas' original Star Wars screenplay bogan is also a derogatory nick name in Australia for someone uncouth or stupid, similar to redneck in the USA or Hoser in Canada. See more
Oh, that's great, Zeb. I'm gonna get eaten, the last *Jedi* in the Galaxy trumped up by some crawlers, because YOU ARE TOO AFRAID TO GO OUTSIDE!