Valley Elderberry Longhorn Beetle

Elaphrus viridis

Description

The valley elderberry longhorn beetle, Elaphrus viridis, is a member of the family Cerambycidae (subfamily Lepturinae) that is distinguished by a cylindrical body as long as 2 in (5 cm). Males of the species exhibit several patterns of coloration: dark metallic green above with a bright reddish orange border; four oblong metallic green spots on the outer wings (elytra); or gradations. Males possess longer, more robust antennae than females. Females are larger than males. This beetle is similar in appearance to the California elderberry longhorn beetle (Desmocerus californicus californicus ). The valley elderberry longhorn beetle has also been classified as D. c. dimorphus.

Behavior

About 400 species of longhorn beetles are found in California; all are herbivorous and are frequently associated with a particular plant host. The valley elderberry longhorn beetle is associated with three species of elderberry (Sambucus ). It deposits eggs in cracks and crevices of the bark of living elderberry bushes; the eggs hatch soon after. The larvae bore into the pith of larger stems and roots and, when ready to pupate, open holes through the bark. The life cycle probably encompasses two years. Adults emerge about the same time the elderberry blooms—as early as mid-March—and may live until mid-June.

Habitat

The valley elderberry longhorn beetle inhabits elderberry thickets in moist oak woodlands along the banks of streams and rivers. The host plant sometimes suffers from fungus attack at the emergence holes bored by the beetle, weakening or killing the plant.

Distribution

This beetle is endemic to the banks of the Sacramento, American, and San Joaquin Rivers and their tributaries in the Central Valley of California. The beetle's major population center is along the American River.

Remnant populations of this longhorn beetle are found in the few stands of natural riverside (riparian) woodlands that remain in the Central Valley. As of 1988, the beetle was known from 10 localities in five counties: Merced, Sacramento, San Joaquin, Stanislaus, and Yolo. Sacramento County supports the largest concentrations of the beetle.

Populations are found along the American River bordering the American River Parkway; the Merced River in the McConnell State Recreation Area; Putah Creek in Solano Creek Park; and the Stanislaus River. A 1987 survey found beetle emergence holes in elderberry bushes along the Feather, Cosumnes, and upper Sacramento Rivers.

Threats

The primary threat to the valley elderberry long-horn beetle is continued loss of habitat. Riparian woodlands have largely diminished due to agricultural conversion, levee construction, and stream channelization. Elderberry bushes were destroyed during maintenance on the American River Flood Control Project in 1985, but the California Department of Water Resources agreed to replant bushes and prevent future disturbance. In 1987, however, personnel from the state reclamation district mowed the habitat along the east levee of the American River, claiming that all wild growth, without exception, must be removed. This decision was contested by the U. S. Fish and Wildlife Service (FWS).

Conservation and Recovery

In 1986, 430 acres (174 hectares) were purchased by Sacramento County along the American River Parkway. The county plans to maintain this land as a habitat for the beetle and to reclaim portions that were previously used for other purposes.

As part of a mitigation agreement, FWS and state botanists have transplanted elderberry bushes infested with beetle larvae to new locations. At one transplant site near Sacramento, beetles were seen to emerge from transplanted trees in April 1988. A second site near Sacramento's main landfill was destroyed by leaking contaminants. Remnants of riparian woodlands within the historic range of the valley elderberry longhorn beetle are being surveyed to identify other potential transplant sites.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

References

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.

Eng, L. L. 1984. "Rare, Threatened, and Endangered Invertebrates in Californian Riparian Systems." In California Riparian Systems: Ecology, Conservation, and Productive Management, edited by R. E. Warner and K. M. Hendrix. University of California Press, Berkeley.

Sands, A. 1982. "The Value of Riparian Habitat."Fremontia 10: 3-7.

U. S. Fish and Wildlife Service. 1984. "Valley Elderberry Longhorn Beetle Recovery Plan." U. S. Fish and Wildlife Service, Portland, Oregon.