Valley Elderberry Longhorn Beetle (Coleoptera: Cerambycidae)
Scientific Name: Desmocerus californicus dimorphus
Date of listing: 1980
Federal Status: Threatened
State Status: None
The Valley Elderberry Longhorn Beetle (Coleoptera: Cerambycidae) is a medium-sized (about 2 cm long) beetle. The 'dimorphus' in its name refers to sexual differences in appearance. The forewings of the female are dark metallic green with red margins, whereas those of the male are primarily red with dark green spots.
This beetle is associated with elderberry trees (Sambucus spp.) in California's Central Valley during its entire life cycle. The adults emerge from pupation inside the wood of these trees in the spring as their flowers begin to open. The exit holes made by the emerging adults are distinctive small oval openings. Often these holes are our only clue that the beetles occur in an area. The adults eat the elderberry foliage until about June when they mate. The females lay eggs in crevices in the bark. Upon hatching the larvae then begin to tunnel into the tree where they will spend 1-2 years eating the interior wood which is their sole food source.
In the Central Valley the elderberry tree is associated with riparian forests which occur along rivers and streams. Historically the beetle ranged throughout the Valley. However, recent surveys have revealed the beetle to persist only in scattered localities along the Sacramento, American, San Joaquin, Kings, Kaweah, and Tule rivers and their tributaries. Over 90% of our riparian forests have been cleared in the past century for agricultural, as well as urban and suburban, development. The wood from these forests has also been used extensively as fuel and building materials. Additionally, extensive use of pesticides, grazing and other mismanagement have severely degraded otherwise undisturbed patches of riparian habitat.
Current efforts to save the Valley Elderberry Longhorn Beetle have focused on revegetating riparian habitats. The California Department of Water Resources has assisted the U.S. Fish and Wildlife Service in replanting elderberry along parts of the American River. Efforts are currently underway to reintroduce the beetle itself into areas which it formerly inhabited. Some success has been acheived by transplanting inhabited trees to a site near Sacramento.
For further reading:
Barr, C. B., 1991. The distribution, habitat, and status of the Valley
Elderberry Longhorn Beetle Desmocerus californicus dimorphus
Fisher (Coleoptera: Cerambycidae). U.S. Fish and Wildlife Service.
Sacramento, CA.
Eng, L. L., 1984. Rare, threatened and endangered invertebrates in California riparian systems. In: California riparian systems Ecology, conservation, and productive management, ed. R. E. Warner and K. M. Hendrix. Berkeley: University of California Press.
