Notes:

Bark beetles are adapted to carry their own microflora. These images show root-stain fungi and bacteria carried in pockets in the bark beetle's carapace. The beetle rubs the fungi off onto the tree as she enters bark. As the fungi grow, they choke off the flow of sap, thus protecting the beetles from the tree's defenses. From: "Major Root Diseases And Their Insect Associates In Trees Of The Inland Northwest", by Drs. Arthur D. Partridge and Catherine L. Bertagnolli.