The Ayappa or Sastha worshipped at the famous Cherthala Karthyayani Devi temple at Cherthala in Alappuzha district, Kerala, is known as Kavu Udayon. The term means king or owner of the groove or kavu. As per local belief, the entire grove or temple area was ruled by Sastha. Goddess Karthyayani murti in the temple was consecrated later.
The deity is standing posture holding a mace or gada. There are two other murtis in the sanctum sanctorum here one is that of Ayyappa in the same posture as we worship in Sabarimala. The other is that of Bhootha Natha Swamy holding bow and arrow. It is believed that Bhootanathaswamy is an amsha avatar of Ayyappa or Sastha.
As per a popular story in the region, people requested Sastha to find a solution to the problems in the region created by a gandharvan. Ayyappa came out of the temple and annihilated the gandharvan and saved the living beings of the region.
When he was returning back to the temple, Goddess Cherthala Karthyayani Devi asked him to reside outside the temple to protect the people of the area. A separate temple was built outside the temple complex for Ayyappa.
A unique offering to the Kavuudayon temple is Gada or mace. The mace is made using wood and colored. The offering is made to overcome fear. It is also offered by people who are trouble by supernatural elements or evil spirits.