From the text:
BLANCHE: Flamingo? No! Tarantula was the name of it! I stayed at a hotel called the Tarantula Arms!
MITCH [stupidly]: Tarantula?
BLANCHE: Yes, a big spider! That's where I brought my victims.
Blanche excuses her behavior by saying that after her husband's death she needed to fill the void in her heart.
Yes, I had many intimacies with strangers. After the death of Allan--intimacies with strangers was all I seemed able to fill my empty heart with.... I think it was panic, just panic, that drove me from one to another, hunting for some protection--here and there, in the most--unlikely places-even, at last, in a seventeen-year-old boy but--somebody wrote the superintendent about it--"This woman is morally unfit for her position!"