Biological controls for weeds—that is, introducing animals that eat them—can be a wonderfully economical and ecologically friendly alternative to mechanical (mowing) and chemical (herbicide) controls. We’ve all heard horror stories about how badly things can go wrong when the critter that’s been introduced to the environment does its job too well, or eats more than it was intended to, or devours something entirely unexpected. But the practice has been used successfully for years, and in some places it’s becoming a thriving private business.
A few months ago, an Erosion Control article described how owners of a solar array were keeping plants under control. Rather than placing the usual gravel bed—which would also have required periodic weeding—under their 22-inch-high solar panels, the owners had planted native vegetation. To keep the plants from growing too high and shading the panels, they allowed miniature Babydoll sheep—short enough to walk right under the solar panels—to graze the area.
In Arizona’s Tonto National Forest, goats have been used to munch on up to 1,600 acres of underbrush, consuming excess fuel and reducing the risk of wildfires.
Several companies have gotten into the business in a big way, renting out herds of goats to clear invasive plants and weeds. CT Biological Weed & Brush Control in Idaho has several hundred goats, and Prescriptive Livestock Services now has 7,000 goats in five Pacific Northwest states.
Sheep and goats seem like a pretty easy thing to keep track of; insects, less so. An Associated Press article two weeks ago detailed California’s attempts to control invasive water hyacinth (the same plant for which nutria were once used to control in the Southeast US) by releasing insects native to South America—the water hyacinth plant hopper. Before deciding to release them, scientists experimented with about 90 species of plants native to the area in which the bugs will be released, and they’re satisfied the water hyacinth plant hopper will eat water hyacinth and nothing else.