Introduction
Kadru is a wife of the sage Kashyapa and the mother of the Nagas, the serpent race of Hindu mythology. She is the sister and rival of Vinata, the mother of Garuda. Her name is often translated as "tawny" or "reddish-brown".
Family
Sons
Kadru asked Kashyapa for a thousand sons of equal power, and he agreed. She laid a thousand eggs, from which came the Nagas, who include some of the most famous serpents of Hindu mythology: Shesha (Ananta), on whom Vishnu rests; Vasuki, used as the rope in the churning of the ocean and worn by Shiva; Takshaka, who killed Parikshit; Karkotaka and Airavata.
The wager
Kadru's wager with Vinata over the colour of the tail of the horse Uchchaihshravas is the main story. When she asked her sons to hang from the horse's tail to darken it, some refused. Kadru cursed them to be burnt in a snake sacrifice. The curse was later fulfilled when King Janamejaya held the Sarpa Satra to avenge his father's death by the serpent Takshaka, and it was ended by the sage Astika, whose mother was the sister of Vasuki, and who had been born to save the serpents.
Vinata's freedom
Kadru enslaved Vinata for many years, until Vinata's son Garuda brought the nectar to free his mother. The serpents were prevented from drinking it, and licked the drops on the grass, which is why, in the tradition, snakes have forked tongues.
Worship of the Nagas
The Nagas are worshipped across India, especially on Nag Panchami, on the fifth day of the bright half of Shravana, when milk is offered to snakes and their images. Kadru is honoured as the mother of the Nagas.
Meaning
The story is a myth of the origin of serpents and of their conflict with birds, and reflects the ambivalent Indian attitude to serpents as both dangerous and sacred.