The story says that the famous Vaishnav saint Ramanuja once asked his son Ananthashwar to raise a flower garden for Lord Venkatesh in Tirumala, the abode of bhagwaan Venkatesh.Ananthashwar abided by the request of his father went upon raising a flower and fruit garden for his bhagwaan. 

He took the help of his wife who was pregnant…she found it difficult to do the manual labor from time to time.Lord Venkatesh…saw the trouble of Ananthashwar’s wife…he assumed the form of a young boy and helped her out.On one occasion when this came to the notice of Ananthashwar, the latter was furious and he hit the boy with a crowbar on the chin.The boy then disappeared but when Ananthashwar visited the Tirupati Temple in Tirumala, he found that the Lord was bleeding from the chin.

He at once realised that it was the Lord who had helped his wife in the form of the boy and regretted his act.He Applied green Camphor (karpur) for the wound.Lord Venkatesh was impressed with Ananthashwar’s devotion and not only forgave him but also told him that he would display the Camphor Applied to his chin forever as a mark of Ananthashwar’s devotion towards him. 

Thus, Camphor is Applied to the main idol’s chin to this day during the rituals.Even today you can see Ananthashwar’s Crowbar , when you enter the temple! 

Thank you!