There is something about her uncertain manner, as well as her white clothes, that suggests a moth.

Tennessee Williams's description of his character Blanche duBois is, indeed, apt as, moth-like, she is never definitive, she desires illusion, and she courts danger.

Indefinitive 

• When Blanche first arrives at her sister's, she seems flighty, asking what street she is on and realizing that she has arrived earlier than expected. After the neighbor lets her in, Blanche espies some whisky, takes a furtive drink; then, she tells herself, "I've got to keep hold of myself!"
• Having had, by her own admission, many affairs--"Yes, I had many intimacies with strangers,...even at last with a 17 year old boy"--Blanche is uncontrolled in her desires and has flitted from one man to another, never finding peace or contentment.

Desirous of illusion 

• Blanche is secretive about her past; she creates illusion with paper over the lights and dramatic clothing and charades such as her words, "I have always been dependent upon the kindness of strangers."
• She hides from close inspection--"I like it dark," and changes the subject when Mitch asks her age, for instance. In Scene Nine, she admits,"I don't want realism, I want magic."
• Stanley recognizes Blanches's desire for illusion as he tells her, "How you love it! Having them colored lights going."   

Blanche courts danger

• Blanche's desire--"Haven't you ever ridden on that streetcar?"--leads her into dangerous situations. In Scene Six, for example, Blanche knows what is coming, but is irresistibly drawn to flirting with Stanley. For, about Stanley, she remarks,

The first time I laid eyes on him, I thought to myself, that man is my executioner.

• Blanche's downward spin of desire leads to death, her journey to Elysian Fields. Truth, not illusion that moths seek, brings death to Blanche as her flirtations have effected danger.