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Home » Guide » Arthropods (Arthropoda) » Hexapods (Hexapoda) » Insects (Insecta) » Beetles (Coleoptera) » Polyphaga » Series Cucujiformia » Longhorn and Leaf Beetles (Chrysomeloidea) » Longhorn Beetles (Cerambycidae) » Prioninae » Prionini » Prionus » subgenus Prionus (Prionus subgenus Prionus) » California Root Borer (Prionus californicus)
Photo#454984
Long horned giant wood borer? - Prionus californicus - female
Copyright © 2010 gophervalley

Long horned giant wood borer? - Prionus californicus - Female
Gopher Valley near Sheridan about 400 ft elevation, Yamhill County, Oregon, USA
September 10, 2010
Size: 5.5 cm head to hind end
My neighbor and I each found a dead beetle outside here in tree-farm/vineyard country - do they die soon after emerging? If this is indeed a giant root borer, the fieldguide says they take up to 3yrs to mature, but doesn't say much about the adults except they lay eggs near trees & shrubs and the larva enters the wood. Not sure why it's called a root borer in that case... the guide also states it is the largest long horned beetle in N Am - doesn't seem THAT big, but this is the biggest beetle I've seen in the NW, and if it was alive, it would be very impressive! Thanks for any info. I am assuming since there are not hordes of them (yet) they are not a huge threat to the forest of dougfirs or Oregon white oaks. Small note: this one had a deformed front leg.
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Contributed by gophervalley on 15 September, 2010 - 12:10am
Last updated 21 November, 2010 - 6:41pm

Moved
Moved from Prioninae.
… v belov, 21 November, 2010 - 6:39pm login or register to post comments

What you have there is a fema
What you have there is a female Prionus californicus. Since she seems intact (that is, not chewed on by a predator), I would say that she probably fulfilled her biological duty and laid her eggs. She lays them in the ground at the bases of the host plants (just about any plant in this case), and the eggs hatch into larvae, which burrow in the soil, finding the roots of the hosts and feed until they reach maturity. This takes about 2-3 years.

The female uses a pheromone to attract males, then mating quickly occurs. The males are smaller, and have larger antennae which are elaborately articulated into serrations and plates which increase their surface area, thus enhancing their ability to detect the female pheromone.

The female of this species is quite large, and may well be the largest longhorn beetle in mass, but the palo verde root borer (Derobrachus spp.) is the largest in terms of length. Prionus is very common and there are probably hundreds per acre in natural habitat, but less common in developed areas. Hope that helps!
… Ian Swift, 15 September, 2010 - 5:29pm login or register to post comments

 
Prionus californicus
That is so cool! The guide I had did say large in mass rather than length. I saw the larva photos on your Prionus page.

Thanks a bunch. I'll post the info on my blog: http://gophervalleyjrnl.wordpress.com (spreading the 'gospel' of biodiversity via my oak savanna restoration project adventures)

Thank you for being so generous with your expertise - I have gotten great info from spideridentification.org too, but this is my first post on bugguide.
… gophervalley, 15 September, 2010 - 8:34pm login or register to post comments

 
Not a problem. Feel free to
Not a problem. Feel free to share more interesting finds.
… Ian Swift, 17 September, 2010 - 12:08am login or register to post comments

Moved
Moved from ID Request.
… Brad Barnd, 15 September, 2010 - 3:59pm login or register to post comments

Prionus?
Looks like a Prionus to me...love them!
… Jenny Souza, 15 September, 2010 - 2:41am login or register to post comments

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