SHADY COVE, Ore. — An innocuous-looking moth with some badass offspring may be on its way to becoming the weapon state agriculturalists employ against the newest invasive weed to spread like, well, weeds in Jackson County. The Oregon Department of Agriculture has turned to the rush skeletonweed moth to help stem the spread of its namesake, a spindly and easily overlooked plant moving up the Rogue River banks and threatening to muck up agricultural pastures. Both the moth and the weed hail from Eurasia, and the moth’s larvae is the only caterpillar to feast on the plant’s deep roots. Because the plants sport tiny leaves, they are not easily quelled by herbicides.