After Wilbur the "humble" pig is saved from being slaughtered (ultimately, by the attention lavished upon him at the county fair with the help of Charlotte's magnum opus of web words), Charlotte lays an egg sac with five hundred and fourteen eggs.
Exhausted, Charlotte tells Wilbur that she will not be able to return to the Zuckernman's farm, and she tragically dies. Wilbur is left in charge of guarding Charlotte's egg sac, which is placed in Wilbur's crate by Templeton the rat.
The baby spiders eventually hatch the next spring, but quickly disperse, floating away on the breeze. Only three spiders decide to stay behind--the smallest of the bunch. Wilbur gleefully names the trio "Joy," "Arenea," and "Nellie," and the pig feels great hope that the memory of Charlotte and his friendship with her will live on through her offspring.
At the fair, Charlotte dies before she is able to return to the Zuckerman farm, but after laying her eggs. Wilbur convinces Templeton to hide the egg sack in his crate so that they can bring them back to the farm.
To Wilbur's disappointment, once Charlotte's eggs hatch (in the spring) they all begin to leave him and be taken away by the wind. Wilbur's sad that all of them have left him, but he realizes that three have stayed behind to be his friend. He names them Joy (because he's excited they stay behind, Arena (which is Charlotte's middle name), and Nellie. Even as the season changes and he gains new friends, he never forgets Charlotte, his first true friend.