“Flies are more than just mooches who spread disease,” declares the jacket copy for Focus on Flies by Vancouver’s Norma Dixon. Any child who has been exposed to enough nature shows and animal books knows that bad things exist for a reason – even if only as food for something slightly less bad.

Even so, it takes Dixon – whose previous book was, appropriately enough, Lowdown on Earthworms – nearly two thirds of this slim volume to actually offer a couple of positive facts about flies. And even then, one is about fly larvae eating up all the dead things around us and the other is about a pair of poachers being caught thanks to the blowfly eggs found on the bodies of two bear cubs. Not exactly Disney.

All told, Dixon’s book offers about four positive reasons for the existence of flies, a total far outweighed by all the evidence given as to just how devious, skillful, well adapted, ubiquitous, and, ultimately, unbeatable flies really are.

All of this information is presented in a very no-nonsense format, with numerous full-colour illustrations and a few photographs. Everything is divided into very short chapters that, aside from a few notes about ancient Egyptians, doomed lion prides, infested hospitals, and the like, stick close to their tiny subjects and avoid too much gross-out material. This should please teachers and parents, though some kids might yearn for more nasty stuff. But really, aren’t kids just mooches who spread disease?