Most of these are valuable, especially to the farmer, because they eat great numbers of mice, rats, ground squirrels, gophers and such rodents. Several of the smaller kinds prey largely upon insects. Others eat earthworms, frogs, toads, or fish and aquatic animals, but do little harm because such creatures are plentiful. The poisonous snakes kill with their venomous fangs. Others merely seize the animal in their mouth and gradually swallow it, alive and whole.
Some kinds lay eggs and some give birth to living young.
Usually, the young appear in late summer or early fall. The Pilot Black Snake, the Fox Snake and the Bull Snake are all common, all lay eggs, and are all large. The Common Water Snake, the Queen Water Snake, the Common Garter Snake, and the Plains Garter Snake are very abundant, all bear their young alive, and all seize their prey in their mouths. All those named here are harmless. A snake is frequently hard for the ordinary person to identify.