One of the central images that governs this brilliant play is that of the moth. This is a creature that Blanche is compared to explicitly in the stage directions as she first enters the play in Act One, and the references continue throughout the play. In a sense, this piece of imagery is particularly apt for Blanche in many ways. Not only is she soft, delicate and vulnerable, but she has a tendency to play with fire and be drawn to it, even when it hastens her own demise.
An excellent example of this is of course in Act 5, when we see the way in which Blanche, after protesting about the "epic fornications" of her ancestors in Act 2, shows the way that she herself is unable to conduct herself appropriately in a sexual fashion when she begins to flirt with the Young Man and kisses him whilst waiting for Mitch to appear for her first date. The juxtaposition of these two events shows the way that Blanche, just like a moth, is drawn to the flame that will eventually burn her up.