Until now, costly insecticides have been only a deterrent against spruce beetle infestations. After spruce beetles enter a tree nothing has been available to save it. Now, however, our spruce beetle fleas, which feed and breed exclusively on spruce beetle larva, can cheaply save hectares of our northwest spruce trees. When dropped into a forest, our fleas, tuned to follow spruce beetle pheromones, smell them out, and hunt them to extinction. We have a lot of work ahead of us. We are working on the genetics of fleas to target other beetles that harm trees, particularly the Asian longhorned beetle on the East Coast of the U.S., the black turpentine beetle that attacks pine forests, the Douglas-fir beetle, the redbay ambrosia beetle, the eastern pineshoot borer, the emerald ash borer, IPS bark beetles, the mountain pine beetle that attacks lodgepole, ponderosa, sugar and western white pines, southern and western pine beetles, the white pine weevil, and various shade tree borers. Our fleas are adept at getting borers. They enter through the same holes, burrow through sawdust-congested tunnels, and find their targets, day and night, in any weather.