how did the creatures grow to be so big?

The Centipede begins to tell James the story of how he became such a marvelously large centipede. He was going about his business in the garden under the peach tree, when suddenly a little green thing wiggled past his nose. Other insects - the Ladybug, Miss Spider, and the Old-Green-Grasshopper - also claim that they saw the same thing, and James exclaims that he knows what it was: the magic items. The creatures all say that they ate one, two, or three of the green creatures, and as they are about to complete the story, the Old-Green-Grasshopper urges them to get ready for bed because they have a long day ahead of them the next day.