Bark beetles – members of the weevil subfamily Scolytinae which colonize living or dead trees and feed on the actual tree tissues, usually phloem. Ubiquitous in forests worldwide. Several species are well-known for coordinated mass-attacks on live trees and occasional outbreaks. Approximately 5000 spp. The ancestral group of most ambrosia beetles. Many species are also intimately associated with fungi, often with tree pathogens.