A major theme of the book is perseverance, which is vital for the pioneer spirit. It is a hard struggle for the Ingalls family to establish themselves by Plum Creek. They live in a dugout and they meet with a series of natural disasters, the most devastating of which is a plague of grasshoppers which utterly destroys their wheat crop. The harvesting of the wheat is something that they had been pinning their hopes on, and when it is ruined they have to draw on all their inner strength to keep going.
As is clear from the following quote, Pa shows a firm determination not to give up, and Ma fully supports him in her own quiet way:
Pa straightened up. His dim eyes brightened with a fierce light, not like the twinkle Laura had always seen in them.
‘But I do know this, Caroline,’ he said. ‘No pesky mess of grasshoppers can beat us! We’ll do something! You’ll see! We’ll get along somehow.’
‘Yes, Charles,’ Ma said. (chapter 26)
Pa is as good as his word, and tramps hundreds of miles to find work elsewhere. He also shows great resilience to survive a fierce blizzard. Pa and Ma inculcate their own values of patience, endurance and resolve in their children. Laura and her siblings benefit greatly from this.
Laura Ingalls Wilder's message, or theme, in On the Banks of Plum Creek is that a person can learn a lot from those around them. Ma and Pa prove this through their continual efforts to put their children first. They go without things that they want or need so that their children get first. In addition to always putting others first, they do so without complaint. They try to instill these values in their daughters. They teach them the value of hard work by assigning them chores -such as cleaning out manure- that are physically demanding and expect them not to complain.