Bark beetle
| Bark beetles | ||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Missing image Dendroctonus_ponderosae.jpg Adult mountain pine beetle Dendroctonus ponderosae | ||||||||||||||||||||||||||
| Scientific classification | ||||||||||||||||||||||||||
| ||||||||||||||||||||||||||
| Genera | ||||||||||||||||||||||||||
|
See text |
A bark beetle is one of approximately 220 genera with 6000 species of beetle in the family Scolytidae, or (as treated by some entomologists) the subfamily Scolytinae of the weevil family Curculionidae.
They are known for their ability to bore into the cambium layer of trees to lay eggs and reproduce. Some species, such as the mountain pine beetle (Dendroctonus ponderosae) attack and kill live trees. Most however, live in dead or dying hosts. Bark beetles are ecologically and economically significant. Even outbreak species can help to renew the forest by killing old trees. Other species aid in the decomposition of dead wood.
Dead_pines.jpg
Bark beetles often attack trees that are already weakened by disease, drought, smog, and physical damage. Healthy trees may put up defenses by producing resin or latex, which may contain a number of insecticidal and fungicidal compounds that can kill or injure attacking insects, or simply immobilise and suffocate them with the sticky fluid. Under outbreak conditions, the sheer number of beetles can however overwhelm the tree's defences.
Bark beetles are also noteworthy for their symbiosis with fungi. The ambrosia beetles (such as Trypodendron spp.) feed on fungal "gardens" and are one of only three insect groups (Termites, ants) known to farm fungi. Others, like the mountain pine beetle, use symbiotic fungi to help kill their host trees.
Beetles will emit pheromones to attract other beetles, which are drawn to target trees and may result in heavy infestation and eventually death of the tree.