The Ayilyam Mahotsavam is an annual festival held at the Sree Nagaraja Swami Temple in Vettikode, Alappuzha district. This ancient shrine, dedicated to the serpent gods, becomes the center of vibrant festivities and deeply rooted rituals during this time. The celebrations commence seven days before the Ayilyam asterism in the Malayalam month of Kanni, which typically falls around September or October. Each day leading up to the festival is marked by special rituals, drawing devotees from across the state to participate in and witness these sacred proceedings.

One of the festival's key highlights is the ceremonial procession from the Sree Nagaraja Swami Temple to the Meppallil Illam, an ancient Brahmin home. This procession is a significant event that symbolizes the deep connection between the temple and the traditional Brahmin households. The evenings are particularly notable for the Sarpabali ritual, performed to appease the serpent gods. This ritual involves offerings and prayers, creating a mystical atmosphere that resonates with the devotion of the participants.

The festival's significance is deeply rooted in the mythology and cultural practices of Kerala. According to legend, the serpent gods are believed to grant prosperity, health, and fertility to those who worship them with sincere devotion. The Ayilyam Mahotsavam is especially important for childless couples, who participate in the Uruli Kamazhthal ritual, conducted beneath the temple's sacred tree. This ritual is believed to eliminate the Kalsarpa dosh (serpent curse) and bestow the blessings of children upon the devotees.

The festival is also a showcase of Kerala's rich cultural heritage, with various art forms and traditional performances enhancing the celebratory atmosphere. Devotees and visitors are treated to performances of folk arts such as Kathakali and other traditional dances, which add to the vibrancy of the festival. The temple grounds and surrounding areas are adorned with decorations, lights, and vibrant colors, creating a festive ambiance that is both spiritually uplifting and visually captivating.

The culmination of the Ayilyam Mahotsavam is marked by the grand ritual of Sarpabali, held in the evening. This ritual, performed with great reverence and precision, involves offerings to the serpent gods and is considered the most important ceremony of the festival. Devotees believe that participating in this ritual brings protection from snakebites and other dangers, as well as overall well-being and prosperity.

The Sree Nagaraja Swami Temple itself is an architectural and spiritual marvel, known for its serene setting and the sacred grove that surrounds it. The temple's history is intertwined with the legends of serpent worship in Kerala, making it a significant pilgrimage site for devotees seeking the blessings of the serpent gods.