Catholics do not pray to statues.
That would be idolatry and therefore, a violation of the First Commandment. If a person prays to a statue out of superstition, believes that the statue has special powers or is even God – that is idolatry.
However, this is not what Catholics do when they pray in front of a statue. Catholics worship with their whole person and all of the senses. A statue, or any other piece of religious art, is intended to draw the soul deeper into prayer by helping the senses to recall the mystery that it represents.