Palo Verde Root Borer

Appearance

It is a longhorn beetle native to the southwestern United States and northern Mexico which derives its common name from the palo verde tree, and it is one of the largest beetles in North America, reaching up to three and a half inches in length. Adults are black or brown in colour, have long antennae, and spines on the thorax. They have wings and can fly, albeit awkwardly at times. Mature beetles emerge in the summer to mate. While not harmful to humans, they can bite in self-defense.

Naming

For over 100 years, this species was confused with the related species "Derobrachus geminatus", and only recognized and given its own name by Santos-Silva in 2007; essentially all literature prior to 2007 therefore incorrectly uses the name "geminatus" for this species.

Reproduction

"Derobrachus hovorei" hatches from eggs into grubs, which live underground for as many as three years; as a result, the huge grubs can be uncovered by gardeners doing routine yard maintenance, especially in flower beds surrounding lawns which contain susceptible trees. The larvae are cream coloured to pale green, typically with a brown head, and feed on the roots of trees, causing branches to die back. In the wild the most commonly affected tree is the palo verde, although wild specimens of other "Parkinsonia" species are attacked as well. In urban areas where species of "Parkinsonia" are not often found, "D. hovorei" can feed on the roots of a variety of trees, including the Siberian elm, white and fruitless mulberry, various cottonwoods and, in the warmest desert areas, citrus.