Tamarisk: Delta County tamarisk leaf beetle release update

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From Painted Sky Resource Conservation & Development via the Delta County Independent:

This summer Painted Sky Resource Conservation & Development staff has released tamarisk beetles at five sites in the North Fork Valley and Delta area to battle tamarisk, an invasive shrub from Eurasia. The beetle populations appear healthy and are reproducing well, according to monitoring observations conducted in mid-August.

The release sites, all on private property, range from Bell Creek and Back River Road between Paonia and Hotchkiss on the east to G Road and the Gunnison River northwest of Delta. Properties at the end of Horn Road near Austin and the Gunnison River and Highway 65 and the Gunnison River also received beetles. The fifth site, Confluence Park in Delta, is on public land. The average number of beetles released at each site is about 6,000.

Beetles are the last stage of the life cycle. After hatching from eggs, larvae go through three stages from tiny worms to larger worms or larvae. You can easily identify the third and final stage larvae by a “green racing stripe” on each side of its body. Beetles released earlier this summer have produced the next generation, which are in the third larval stage now. It’s the larvae, not the adult beetles that do the most damage to the plant. Like teenagers with insatiable appetites, they eat 24 hours per day, seven days per week.

The beetles may cause browning of tamarisk by next summer, but it will take up to five years for them to kill the tamarisk.

As the beetle populations grow and exhaust their food supply at the release sites, they’ll fly up and down the river drainage in search of fresh tamarisk to eat. Eventually, they’ll distribute themselves throughout the area. Flying from tamarisk to tamarisk shrub, beetles have moved up the Dolores River from near Moab, Utah, to just south of Gateway without ever hitching a ride with humans.

Painted Sky plans more releases in the area in 2010, including the Surface Creek area, Smith’s Fork and along the Uncompahgre River in Delta. Landowners with tamarisk can ask to be put on a waiting list to receive beetles. Tamarisk or salt cedar has spread too successfully in the West over the past century. It out-competes native plants and trees, such as cottonwoods, creating a monoculture. A landscape dominated by only one plant hurts wildlife diversity.

More tamarisk coverage here and here.

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