How does the author use foreshadowing in James and the Giant Peach?

From Aunt Spiker's name, we can infer she's prickly, distant, and not altogether nice. This foreshadows her cruel treatment of James.

Aunt Sponge is a bit more difficult, but think about what sponges actually do...... Aunt Sponge's name foreshadows her treatment of James. We can infer that she will take the life out of him.