There are several references throughout Fahrenheit 451 to essentially yucky animals and insects (that’s the technical term). When Mildred gets her stomach pumped, the machine is like a snake. The earpiece she wears at night is like a praying mantis. The helicopters in the chase scene are described as insects. Even the Mechanical Hound has eight legs, like a spider. Notice a pattern here? These references all have to do with technology – destructive technology that the government uses to control its citizens. It’s basically a perversion of nature and of the natural order, which fits into the larger themes of Fahrenheit 451 (because in this world of destruction without construction, the natural order is off).