In the Secret Life of Bees to whom is the "secret life" referring?
Your question relates to the importance of bees in the novel and the way that they act as as incredibly powerful motif, in particular in relation to the character of Lily. Let us remember that throughout the novel the bees serve as Lily's silent mentor and guide. It is from them that she "hears" the message that she should run away and leave T. Ray's house. Likewise, it is following the trail of the bees and the Black Madonna that leads her to August's house and the eventual truth about her mother. When she reaches Tiburon, she lives in the honey house and takes up beekeeping as an occupation.
If we consider bees for one moment, they seem to function in the novel as a symbol of sexual maturity, personal growth and exploration, which of course parallels with the way in which Lily herself experiences these aspects of life. What is important to note is the way that bees are involved in every important action Lily makes in the novel, especially with regard to her emotions. For example, when she realises that she loves August, bees rest on her body. When she realises that she has fallen in love with Zach, she licks honey off of his finger:
He dipped his finger into the comb and, lifting my veil, brought it close to my lips. I opened my mouth, let his finger slide in, sucking it clean. The sheerest smile brushed his lips, and heat rushed up my body. He bent toward me. I wanted him to life backmy veil and kiss me, and I knew he wanted to do it, too, by the way he fixed his eyes on mine. We stayed like that while bees swirled around our heads with a sound like sizzling bacon a sound that no longer registered as danger.
The secret life of bees and the way they operate and work together likewise is something that Lily discovers has many parallels with her own life. Their diligence and hardworking nature, the way that they survive and care for their mother inspire Lily and the all-female community and the way that they care for each other again parallels her own reliance and living situation.