An exotic insect with origins in Eurasia that eats invasive salt cedar (tamarisk) is alive and well in San Juan County.
Last summer was the first time the Bureau of Land Management Farmington Field Office began monitoring the bug’s arrival here. This summer the bug (scientific name Diorhabda spp.) is back and thriving.
“We are monitoring its movement,” said Sarah Scott, a natural resource specialist at the BLM Farmington Field Office.
Salt cedar was introduced to the United States from Eurasia in the 1900s to control erosion along waterways. Today, it grows out of control in parts of San Juan County, becoming so dense in some riparian areas there is no room for native vegetation to grow.
In late June, Scott examined a stand of salt cedar along the La Plata River and the salt cedar bug larvae were all over the plants. The larvae stage is when the bug eats the most and does the most damage to salt cedar. The larvae stage is expected to soon become a beetle.
The insect was first openly introduced as a salt cedar biocontrol agent in Utah in 2004.
As the BLM monitors the bug’s movements in San Juan County, the agency is making plans for what to plant in place of salt cedar when it dies. Studies have shown salt cedar dies after four or five summers of the bug defoliating the plant.
Scott said the salt cedar bug also has been discovered along the San Juan River below Navajo Dam and along the Animas River near Aztec.
“This is a good time to start planning rehabilitation projects,” Scott said. “We can plant native cottonwoods and willows where the salt cedar is expected to die, so that other invasive plants such as knapweed don’t move in to take the place of salt cedar,” Scott said.
The larvae of the salt cedar eating bug, found last week on salt cedar trees along the La Plata River.
Salt cedar plants along the La Plata River on Farmington’s west side are being defoliated by exotic bugs.