Subject: Metallic Wood Boring Beetles mating on a native California Black Walnut Branch
Location: Mount Washington, Los Angeles, California
May 17, 2017 2:33 PM
We just discovered these Metallic Wood Boring Beetles “in flagrante delicto” on a twig of a Calfornia Black Walnut in our office garden. They have excellent eyesight and moved to avoid the camera. Interestingly, Charles Hogue does not list any members of the family in his landmark book, Insects of the Los Angeles Basin. We are currently on a mission to attempt to identify the species.
We have put in a request to Dr Doug Yanega at UC Riverside, but meanwhile, we found this information on Dicerca horni Crotch on the UC Riverside Urban Entomology page: “This is a common flatheaded borer of the Pacific Coast states. It belongs in a genus of medium-sized buprestids that are characterized by their dull-bronze color and the prolonged tips of the elytra (plate II, 1; figure 126). Dicerca horni is a dark, grayish bronze, 13 to 25 mm long, and has small, black, narrow, broken ridges on the dorsum. The larvae are approximately 2.33 times longer than the adults. This species occurs on many species of deciduous trees (including fruit trees) and shrubs, inhabiting dead or dying trees or dead wood on living trees. Adults may be seen from April to September. This is not a pest, but we receive many requests for its identification.” The species name led to this BugGuide image of Dicerca hornii (BugGuide has added an additional i to the scientific name) and it looks like a match. There is also a lovely image on CalPhotos. Our image shows some very pretty magenta highlights on the legs and edges of the thorax.
Confirmation Courtesy of James Hogue
This looks like a good name to me. I have specimens of this species from the mountain ranges surrounding the L. A. Basin and from the lowlands of the San Fernando Valley.