Thirteen flies become tasty snacks in this clever reverse counting book about predators and prey.Science meets subtraction in this fresh and funny STEM picture book. A swarm of thirteen flies buzzes along, losing one member to each predator along the way. Whether the unfortunate insects are zapped or wrapped, liquefied or zombified, the science is real--and hilariously gross. Includes a guide to eating bugs, complete with nutritional information for a single serving of flies.