LeConte, 1853 
Derobrachus geminatus, known variously as the palo verde beetle, palo verde root borer, or palo verde borer beetle, is a longhorn beetle native to the American Southwest and northern Mexico which derives its name from the palo verde tree. It is one of the largest beetles in North America and can reach up to three and a half inches in length. Derobrachus adults are black or brown in color, have long antennae, and spines on the thorax which form a collar around the "neck" of the beetle. They have wings and can fly, albeit awkwardly at times. Mature beetles emerge in the summer to mate. They do not eat, and rely solely on their energy reserves until they die in about one month. Not harmful to humans, but can bite if forced to defend itself.
Derobrachus 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 colored to pale green, typically with a brown headcap, and feed on the roots of trees, causing branch dieback. In the wild the most commonly affected tree is the palo verde, although wild specimens of other Parkinsonia species (P. florida, P. microphylla and P. sonorae among the most common) are attacked as well.
Although the insect can cause significant damage to individual trees during its larval phase, the damage is mechanical rather than fungal, and should not be confused with dutch elm disease, in which one of several beetles of the family Curculionidae transmit pathogenic ascomycete microfungi of the genus Ophiostoma from tree to tree. Afflicted trees may not be detected until the infestation is fatal, and treatment is often problematic since the insect's preferred food is the root.
In cities and other domesticated developments (such as parks, college campuses, cemeteries and the like) the absence of sufficient Parkinsonia species has evoked in the beetle a tolerance for a varied diet, including the Siberian elm, white and fruitless mulberry, various cottonwoods and, in the warmest desert areas, citrus.
- "Derobrachus geminatus". Integrated Taxonomic Information System.
- "Palo Verde Grub Fact Sheet".
- "Meet the Beetles".
- "Palo Verde Beetles".