One sticky afternoon last summer, I picked my way through yellow-green grass on the slopes of Humphreys Peak, close to Flagstaff, with Richard Hofstetter, a beetle expert at Northern Arizona University. Looking up the mountain, we could see the skeletal frames of dead trees amid evergreen forest. We entered a stand. The ground was a mess of lifeless branches. Douglas, corkbark, spruce—about half the conifers were dead or dying.
Hofstetter cut a neat rectangle into the spongy surface of a fallen tree and peeled back the bark. Spruce ips, a species of bark beetle, had carved a delta of channels into the underside to feed off the tree’s sap. When enough beetles take up residence, the host tree is overwhelmed and dies. Due to recent droughts, which weaken the trees, and mild winters, which bark beetles prefer, western forests covering an area the size of Maine are under invasion. In the worst-hit regions, like Colorado and British Columbia, entire forests could be reduced to grassland—victims of the largest insect infestations ever to strike North America.
Hofstetter and his colleagues believe they may have found a way to halt this plague: by driving the insects crazy. For years, entomologists have studied the chemicals that the beetles release for mating and communicating, hoping that they could be manipulated as a deterrent or used for control. This approach has had limited success. But in early 2005, Hofstetter met Reagan McGuire, a former truck driver and pool hustler who had quit his job and enrolled at NAU. McGuire had been thinking a lot about the bark-beetle epidemic, and he came up with a novel idea: perhaps a military crowd-control device he had read about, which emits powerful pulses of sound, could be used to kill the insects. Most scientists would have politely ushered him away, and Hofstetter admits he was hesitant. (“He looked at me like I was crazy” is how McGuire remembers it.) But McGuire convinced the entomologist that the idea might have merit, and the two started to collaborate, with McGuire working as a research assistant.