The titular fly carries a lot of symbolic weight. In Western cultures, flies are primarily associated with death and are often interpreted as warnings of impending danger. In the Hebrew Bible, flies operate as signals for human foolishness and warnings of God’s wrath. In Exodus, for example, the fourth plague brought upon Egypt consists of flies, and the seventh plague consists of locusts. The fly, in this regard, can be understood as one step that aided the release of the Jewish people under Egyptian rule.

Shapiro, a Jewish poet, draws on these historical associations—particularly in the context of World War II and rampant antisemitism—to create similar warnings. Shapiro's fly is best understood as an indistinct other whose practices appear disgusting to the speaker but seek a similar end. The speaker’s “hate” (Line 33) toward another creature that means him no real harm mirrors the racism and antisemitism rampant in 1940s Europe. Shapiro stops short of associating the fly with any particular group; instead, it is an indistinct target for the speaker’s rage. The fly thus acts as a foil, or a character that contrasts with the speaker to reveal his contradictory sympathy and spite.