When did they begin to feel home sick and why?

After returning to camp, Tom mentions nothing of his adventures the night before. Instead, the boys take on variety of activities: whopping and prancing, swimming, wrestling, and fishing. But presently, Tom finds himself drawing the name "BECKY" in the sand and both Joe and Huck grow melancholy. They are homesick. After arguing with Tom, both Joe and Huck admit that that pirate life isn't what they expected and wish to return to St. Petersburg.