Describe symbolism in Report from Engine Co. 82 by Dennis Smith

In Chapter Eight, Dennis reflects on his hatred of cockroaches. He feared them as a child. As much as his mother sprayed and cleaned, they were still there. Now the areas where the Irish community lived when he was a child are taken up by Puerto Ricans, but the cockroaches are still there. He has to fight them as he crawls through smoke towards a fire. He used to fear them; now he resents them as to him they represent poverty.