Prionus californicus, commonly known as the California root borer, is a species of insect in the longhorn beetle family (Cerambycidae).

The California root borer occurs widely in western North America from Alaska to Mexico.

It spends most of its life underground feeding on the roots of most deciduous trees and shrubs, as well as some conifers, brambles, and agricultural crops such as hops and grape vines.

[1] The 2.5 to 5.7 cm adults, which are reddish-brown with smooth shiny wing-cases, emerge from the soil from June to early August.

[1] Shortly after mating the female lays cream to yellow-brown 4.8 mm long eggs, of which she can produce up to 200 in her lifetime.