05/27/2026
Today’s Wildlife Wednesday will teach you how important it is to have respect for your elders! But first, did you know there’s a tiny beetle right here in the Sacramento region that can stop a tractor?
The Valley Elderberry Longhorn Beetle, aka VELB, aka Desmocerus californicus dimorphus, is a subspecies of longhorn beetle that’s native to riparian forests (wooded areas along streams and rivers) in the Central Valley of California. This little beetle is not only native to this area, but it’s endemic, meaning it’s found nowhere else on the planet! The Sacramento Valley is a stronghold for the VELB, especially along the American River and Sacramento River corridors.
The adult VELB has an elongated shield-shaped body, measuring 1/2 to 1 inch long. The females have slightly larger bodies than the males, but the males have longer antennae, nearly as long as their bodies. Since the males find females by scent, longer antennae, packed with super-sensitive chemoreceptors, provide them with an advantage, a common trait in insects.
Color and pattern are the best ways to distinguish between the adult males and females. The males’ wing covers, known as elytra, are red with four oval dark spots. The females have a darker metallic green with red margins on their elytra.
The VELB is a threatened species under the federal Endangered Species Act. Threatened species are plants and animals whose population numbers are so low that they may become endangered soon. Endangered species are plants and animals that are in immediate danger of becoming extinct. At the time of its listing in 1980, the VELB was known in only 10 locations along the American River, Putah Creek, and the Merced River.
Since that time, surveys have documented a broader distribution from Redding to Bakersfield. This population expansion is due to conservation efforts that have protected and restored many hundreds of acres of riparian habitat including the beetles’ sole host plant, the blue elderberry.
Valley elderberry longhorn beetles are only found in the vicinity of blue elderberry, a native shrub found in cottonwood forests, mixed riparian woods, and associated open savannas in California's Central Valley. It’s a true mutualistic symbiosis, where both the elderberry plant and the VELB benefit from their relationship with each other. The beetle gets food and shelter, and the plant gets assistance reproducing, thanks to the pollinating prowess of the VELB!
The complete life cycle of the VELB has four stages: egg, larva, pupa, and adult. After mating, the adult female VELB will lay her eggs in crevices on the bark of blue elderberry bushes. After hatching, the larvae bore through the bark into the pith of the elderberry stem where they tunnel and eat for up to two years. To accommodate the larvae, the elderberry stems must be at least one inch in diameter. You’re probably expecting me to come up with a “pithy” comment, but let’s go back to their life cycle.
Inside the elderberry stem, the larva enters the pupal stage and transforms into the adult beetle, which emerges from the stem through a little exit hole. When biologists survey elderberries to search for VELBs, they look carefully for these telltale exit holes. The adult VELBs typically emerge from mid-March to mid-June, about the same time the elderberry blooms. The adult beetles love to eat the leaves and flowers of the elderberry, at the same time, spreading pollen and helping the elderberry with reproduction!
The primary threats to the VELB are flood control activities and urban and agricultural development, resulting in the loss of elderberry shrubs and riparian habitat. When suitable habitat becomes fragmented, it often prevents the adult beetles from dispersing and finding new clusters of elderberry shrubs in which to lay their eggs. As the sole host for federally threatened VELBs, blue elderberry has also become a protected plant species in California.
Whenever work is planned that will disrupt, alter, or convert a tract of riparian habitat, an environmental assessment must be conducted to determine if those changes will have negative impacts on sensitive, listed species. If there are blue elderberry shrubs growing on that land, especially if there is evidence of use by VELBs, that work can be totally halted!
Understandably, this makes some people upset that their plans are foiled by a tiny beetle! It could be that plans for a new shopping mall are halted. Or it could be that a farmer isn’t permitted to manage the vegetation along a canal levee, if elderberry shrubs are growing there. This often creates tension between landowners and environmental regulatory agencies or conservation organizations. We need to seek a balance between land use in our communities and the protection of habitat and biodiversity. Just because an animal is tiny, doesn’t mean it’s any less important in the overall ecosystem.
