Was watching the scene of the 9 guys getting killed and read this comment which I thought had some good points.
"Not sure if this has been said anywhere yet but for those curious about the SPIDER IN THE JAR symbolism:*
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Walt has been chasing flies since Season 4, very much like A SPIDER-- and the symbolism behind that has evolved since then. A fly has come to represent a contaminant-- something that needs to be eliminated in order for Walt to be stable and happy. *
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Walt stares at the fly in the opening of this episode, an obvious allusion to the fact that Mike is a contaminant and they need to rid themselves of the evidence of his murder; as well as the fact that Walt's own impending approach to full-evil is a contaminant-- threatening his business and his family.*
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By the end of the episode, once he's 'out' of the business, a cockroach (or beetle?) is shown crawling across Walt's home, perhaps a nod to the fact that the contaminant has grown exponentially, as well as indicating that Hank is about to find out, since he is the contaminant that has been allowed in the home.*
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So, the SPIDER IN THE JAR is Walt. Despite the fact that he's done chasing flies, and he's out of the business-- he still cannot leave because he is trapped in a jar. He's dangerous, and he's meant to be feared, but he's harmless and hopeless inside that jar that Hank will continue to keep him in."