Finally, the epidemic of Dutch elm disease serves as an allegory for the suburb's attempt to deal with a natural disaster. It is no longer simply the Lisbon's house but the very fabric of the suburb that is falling apart—a mysterious force slowly turns the neighborhood's green canopy to a sickly yellow. Old and venerable, the trees have stood for as long as the boys can remember, and the boys' despair at their sudden removal echoes the boys' shock in Chapter Two following Cecilia's untimely death. Dutch elm, a foreign disease, has crept insidiously into the boys' suburb, leaving behind a scarred landscape. Its presence reflects the arrival and spread of suicide, which the neighbors in Chapter Five describe using the language of infectious disease. The Parks Department's systematic removal of the trees, and the constant buzzing of the saw throughout the spring, also reminds the boys of their own powerlessness against a natural disaster. Though the boys lived among the trees, they are no more able to save them from the Parks Department than they will be able to save the Lisbon girls from fate. The dying trees reflect the book's emphasis on the interaction between humans and their physical environment, and the ways in which the chaos of one is mirrored in and exacerbated by the decline of the other.