Tooele Transcript Bulletin – News in Tooele, Utah
image A prionus californicus beetle was photographed outside a Tooele City home. Unharmed, it ran off to seclude itself in the grass.

August 21, 2014
Prionus californicus larvae are destructive to trees and vegetation

Because of the prionus californicus’s appearance as an adult, many immediately assume that the damaging results of this beetle would occur during its adulthood. However, the only harm an adult prionus californicus is capable of is inflicting a painful bite when disturbed.

The real devastation is caused by the larvae. During its 3-5 years of progressive growth, the prionus californicus’s larvae burrow in the ground to feed on the roots of plants and trees they were laid under. Many inflicted plants include oak, poplar, black walnut, conifers, fruit trees, grape vines, hops, brambles and cane berries. Most of the trees and shrubs that become infested result in the yellowing of leaves and even death.

After prionus californicus beetles outgrow their larvae stage, they immediately seek out mates to reproduce, for their mortality as adults only lasts up to 15 days. Males, during the night time, will locate a female by tracking her emitted pheromones. Once she mates, she will lay her eggs underneath the soil of a provided host tree. There, the eggs will hatch, eat, grow and restart the cycle.

Adult prionus californicus beetles grow up to 2 inches long; they are a sleek reddish-brown color and possess long saw-like antennas. Adults are nocturnal and are attracted to light. In Utah, adults begin to emerge from the soil in July and August. This beetle does not normally appear in desert areas, but does distribute in North America from Alaska to Mexico. The prionus californicus beetle never eats as an adult, its entire focus is spent finding a mate. Not only are these beetles equipped with large mandibles intended for biting pesterers, but they too have wings. So watch out because they fly and bite.


Addie T. Lindsay, age 17, (for one more day), is a writer and photographer of wildlife creatures big and small. She can be contacted at

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