various tree species. While some species, such as the mountain pine beetle (Dendroctonus ponderosae), do attack living trees, many bark beetle species feed on weakened, dying, or dead spruce, fir, and hemlock. Most restrict their breeding area to one part of the tree: twig, branch, stem, or root collar. Some breed in trees of only one species, while others in numerous species of tree. In undisturbed forests, bark beetles serve the purpose of hastening the recycling and decomposition of dead and dying wood and renewing the forest. However, a few species are aggressive and can develop large populations that invade and kill healthy trees and are therefore known as pests. Bark beetles often attack trees that are already weakened by disease, overcrowding, conspecific beetles, or physical damage. In defense, healthier trees may produce sap, resin or latex, which often contains a number of insecticidal and fungicidal compounds that can kill, injure, or immobilize attacking insects. Sap is one of the first lines of defense of pines against bark beetles. Released sap or resins can plug bored holes of bark beetles and seal wounds. Resins also trap insect pests making some initial entry by bark beetles unsuccessful. Chemical compounds can also be induced by tree species that bind with amino acids in the gut of bark beetles, reducing their ability to process woody materials. When in large quantities, the sheer number of beetles can overwhelm the tree's defenses with resulting impacts on the lumber industry, water quality, fish and wildlife, and property values. The oldest known member of the group is Cylindrobrotus from the Early Cretaceous (Barremian) aged Lebanese amber. A species of the extant mostly Neotropical genus Microborus is also known from the Cenomanian aged Burmese amber of Myanmar. Prey relationships Bark beetles are preyed upon by birds such as woodpeckers, other beetles such as the black-bellied clerid (Enoclerus lecontei) and certain other members of family Cleridae, flies such as the long-legged flies (Dolichopodidae), and certain phoretic mites. Phoretic mites use the bark beetle to move from one location to the next, but some of these mite species also prey on the eggs or larvae of the bark beetles or act as parasites. Parasitoids The braconid wasp Spathius canadensis is known to parasitize the native elm bark beetle Hylurgopinus rufipes. Ambrosia beetles Some bark beetles form a symbiotic relationship with certain Ophiostomatales fungi, and are named "ambrosia beetles". The ambrosia