Squashing Spotted Lanternflies Will Get Us Only So Far. We Need Wasps.

Opinion|Squashing Spotted Lanternflies Will Get Us Only So Far. We Need Wasps.

Back in the late 1880s, California citrus farmers found themselves dealing with a crisis caused by a fat bug covered in a shieldlike, granular white wax. Known as the cottony cushion scale, this insect, which had hitchhiked aboard ships from Australia, usually spends its entire life with its mouth affixed to a single plant, greedily sucking out nutrients. Now the bugs were making meals of the state’s citrus trees.

Some farmers resorted to erecting large canvas tents around their trees and fumigating the inside with hydrogen cyanide in attempts to murder the insect, which proved ineffective. That’s when Charles Valentine Riley, who pioneered the field of entomology in the United States, was called in.

In his role as chief entomologist of the U.S. Department of Agriculture, Mr. Riley sent an assistant to the land down under in 1888 to hunt for the bugs’ natural predator. Within three months, a shipment of small branches arrived in California. The branches carried not only cottony cushion scale, but also another bug: the Vedalia beetle, a species of ladybug and a natural predator of the scale. As more shipments arrived, entomologists in California bred the beetles and eventually released them, marveling as the ladybugs dined ravenously. By the end of 1889, the fat cottony cushion scale was no longer a grave threat to citrus growers.

The sharp reduction of cottony cushion scale was one of the United States’ first large-scale programs in biological control, the broad term for using one organism — an animal, a fish, an insect or even a bacterium — to suppress another organism. These efforts won’t fully eliminate a targeted pest. But if done right, they can drive down a pest population to levels where future damage is minimal.