Invasive pests spotted in county
West Nile virus isn’t the only invasive organism to infiltrate Nevada County this summer. Two other threatening non-natives – the defoliating gypsy moth and the water weed hydrilla verticillata – have also been spotted recently.
Although gypsy moths practically became Nevada County residents during the 1990s, the county hasn’t found a gypsy moth since 1999, said county Agricultural Commissioner Paul Boch.
If the moths are here, they’re usually found – drawn to one of the two traps per square mile that have been placed around the county and baited with a female moth hormone.
After a single male gypsy moth was caught at the Omega rest stop off Highway 20 on July 16, Boch’s crew intensified their trapping in the area. So far, his three experienced trappers haven’t found another moth, Boch said.
If they do discover an egg mass, proof the moths are reproducing here, then pesticide will be used. Boch said his staff will continue trapping intensely around the Omega rest stop for two years.
Gypsy moths can be easily confused with other moths, Boch said. The female cannot fly, and the male is about three-fourths of an inch long and has brown wings with dark wavy lines.
After decimating forests on the East Coast and in the Midwest, gypsy moths haven’t been able to conquer California. Boch credited the state’s stiff agricultural screening and thorough testing program, as well as its geographical luck for the success.
“The whole purpose is to find an infestation before they get started,” Boch said. “Luckily we have some high mountains.”
The Sierra hasn’t been able to stop the spread of another problematic invasive known as hydrilla. Several weeks ago, a strand of the rapidly growing plant was found for the first time in Nevada County in a fire suppression pond at the McCourtney Road Transfer Station, Boch said.
Technicians with the state’s Integrated Pest Management program will eradicate the vine-like weed in that pond and survey area waterways, Boch said.
Hydrilla clogs ponds and streams, displacing native creatures and preventing navigation. It has rough leaves with sawtooth edges and small “potato-like, peanut-sized” tubers on the roots, according to the California Department of Food and Agriculture.
If you think you have found a gypsy moth or hydrilla on your property, put it in a bag and bring it to the Nevada County Agriculture Department located in the Veterans Memorial Building, 255 S. Auburn St., Grass Valley.
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