McGuire, watching the action on a computer monitor and listening to the beetles through a headset, said when he played the manipulated sounds he watched "in horror as the male beetle would tear the female apart." At least that's the way it worked in the lab.
It sounds like we could be facing healthy, but very noisy, trees in the future. But the researchers hope to minimize the environmental impact by venturing into the realm of ultrasound. They hope to generate sounds that can be heard by beetles, but not by humans, and still get the job done.
The result that Hofstetter said he hopes to see in the actual forest is living trees, stuffed with beetle carcasses. That may sound a bit extreme, but beetle invasions cause billions of dollars in damages every year.
Last year, 10 million acres were wiped out in Canada's British Columbia. Entire forests have been killed in Alaska, leaving dead timbers that are ripe for fires. The problem has persisted throughout much of the West.
The bark beetles that are attacking pines in many western states are tiny, only about a quarter of an inch long, but they are powerful killers. They eat the tree's living tissue, the phloem, just below the bark, and they can kill a mature tree within a day or two.
They also move through a forest so quickly that the invasion can get out of control virtually overnight. If only a few trees are infested, they can be cut down, saving the rest. But in many cases the beetles spread so fast that the entire forest is lost.
Various efforts to control beetles have met with limited success. Beetles can tell by the odor given off by a tree whether that tree is a ripe target. So a few years ago researchers at Simon Fraser University in British Columbia tried to create an odor that would confuse the beetles, making trees that would be good candidates smell unattractive.
Similar approaches have been taken by other researchers, but so far, the beetles have learned to ignore the false odors.
Chemical odors and pesticides have proven disappointing, to some degree. Next summer, Hofstetter and his colleagues will try to succeed where so many others have failed. Billions of trees could use the help.