Resolving a Politically Fraught Problem By Natural Means

Texas officials release reed-eating Arundo wasps into a thicket of the invasive weed Arundo donaxa, also called carrizo cane, in an effort to weaken or eradicate the plant.Photograph by Victor J. Blue/Bloomberg via Getty

With all the talk about building a wall along the US/Mexico border, it’s rather refreshing to read about this joint program between the U.S.D.A. and Customs and Border Protection to attempt to tear one down.

The problem is a fast growing invasive grass that sucks up water resources, crowds out native plants, and can grow as tall as a 2-story building, . The elegant solution of using stingless wasps whose larvae happily munch on the vigorous plant is elegant compared to options such as bulldozing or aerial spraying of herbicides.

Someone wandering along the banks of the Rio Grande, on the American side, in the summer of 2009 might have been startled by a small cardboard box plummeting to the ground. Neatly sealed with blue packing tape, its paper wrapping crisp and clean, the box would have felt light, even empty. But then, on further inspection, an observer would have noticed the platoon of tiny black insects exiting a slit on one end. Slightly larger than a gnat, the insects would have buzzed off, one by one, into the South Texas heat.

The insects were wasps, which hours earlier had been taken from a refrigerator at the Moore Air Base, in Edinburg, Texas, where they’d been maintained in a soporific state, and placed, with utmost care, in the belly of a Cessna 206 by John Goolsby, an entomologist for the U.S.D.A. Agricultural Research Service. Between 2009 and 2012, 1.2 million wasps—at least a hundred per box—rained down along a five-hundred-and-eighty-eight-river-mile stretch of the border from Brownsville to Del Rio, as part of a joint program between the U.S.D.A. and Customs and Border Protection.

The wasps—which are not the stinging kind—are harmless to humans, but they do inflict damage on a very particular target: Arundo donax, an invasive grass that lines the banks of the Rio Grande in thickets, looking like a hybrid between a corn field and a bamboo forest. Brought to the New World as a building material, the grass has, over the last four hundred years, ruthlessly colonized the waterways of the southern U.S., driving out the native plants in its march to botanical dominance. It flourishes along the rivers of Texas and the Southwest like nowhere else; as much as a hundred thousand acres of the Rio Grande Basin are infested with it. Arundo wasps, which the U.S.D.A. imported from France and Spain, insert their ovipositors into the growing cane shoots to lay eggs, which soon hatch into hungry larvae that burrow through the vigorous plant, rendering it somewhat less savagely aggressive.

Arundo donax, also known as giant reed, carrizo cane, and border bamboo, can grow as tall as a two-story house. Along the border, it forms a grassy forest, within which visibility is roughly twelve to twenty-four inches, and makes an excellent hiding place. This accounts for why Customs and Border Protection put up $9.7 million to send a bunch of boxes of wasps plummeting to earth.

Read the entire article here.

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