Contains four stories for children, including the title work, a cumulative tale in which a wakeful flea atop a number of sleeping creatures causes a commotion with just one bite.
Discusses the history of bloodsucking lice and fleas, examines their family trees, anatomy, life cycles, predators, and prey, and looks at myths and facts about the insects, as well as how to get rid of them.
Bertie finds trouble everywhere, and in this trio of adventures he has plans for his dog's fleas, locks a substitute teacher in the storeroom, and has an encounter with a fire engine.