Elephant dung is known as the poor man's mosquito repellant. When burnt, it gives out a pungent smoke that keeps mosquitoes away.
Munia Devi, 40, and Bholua, 12, spend hours in the haathi bazaar (elephant market) section of the cattle fair, collecting elephant dung, drying it and then selling it. Each ball of elephant dung sells for anywhere between Rs.2 and Rs.4.
"It is more profitable than working in a farm or elsewhere," Munia Devi said. "Some days we earn more than Rs.100."
She has competition. "Elephant dung has become a new source of livelihood for poor people like me," says another seller Mukesh Rai. "But there is severe competition to collect it."
Chandeshwar Singh, a security guard at the fair held in this town about 35 km from state capital Patna, said elephant dung is selling like hot cakes. "Poor people, mostly from rural areas, are buying small balls of it."
"It is a very popular item, we are purchasing it as it is affordable and effective as a mosquito repellent," said Surajdeo Yadav, a small farmer from Raghopur in Vaishali district, one of the hundreds of people who had bought a ball.
Muneshwar Singh, who has brought his elephant to the fair, said: "You can make 40-45 balls out of one kg of dung."
Samrendra Singh, owner of another elephant, said: "Elephant dung is the cheapest available mosquito repellant without side effect."
Manohar Paswan, who had come to the fair from a nearby village, said: "We are using this to save our cows from the mosquito menace, which becomes very bad in early winter."
There are around 50 elephants at the fair this year. They are brought for show, as their sale at the fair is banned under wildlife protection laws, said a forest department official. Elephants are big attractions at the fair, especially for foreign tourists.
But there are unofficial reports that elephants are bought and sold at the fair in the garb of gifting them.
The nearly-month-long fair, spread over 500-odd acres near the confluence of the Ganga and Gandak rivers, has been held every year for centuries. It begins on Kartiki Purnima, an auspicious day in the Hindu calendar.
Apart from cattle, many birds and animals -- parrots, eagles, horses, sheep and goats -- are bought and sold at the fair.