Xyleborus monographus
Xyleborus monographus, the Mediterranean oak borer, is a species of ambrosia beetle in the family Curculionidae.
It is native to oaks in the regions around the Mediterranean Sea, but since 2019 has been found in California, where the oak trees it infests may be more vulnerable.
Native habitat
The Mediterranean oak borer is around long. It is native to the regions surrounding the Mediterranean. In these parts of Europe, the Middle East and North Africa the beetle mostly infests dead and dying oak trees. It is found in at least twelve species of oak. As with other ambrosia beetles, it carries symbiotic ambrosia fungi, which it cultivates for food along the boring tunnels. One of these fungi, Raffaelea montetyi, seems linked to wilt disease in cork trees in Portugal.When the females fly to another tree they carry the fungal spores in their mycangia. The beetle penetrates through thin or cracked bark in the canopy branches. It first invades and kill branches in the canopy of a tree, then spreads to the trunk, culminating in the death of the tree. The females produce two or more generations annually. Large populations can develop in the lower trunk over a number of growing seasons. The fungi take nutrients from the xylem, which transports nutrients from the roots of the tree to its stems and leaves. Mechanical damage seems to cause the greatest amount of damage, since the extensive tunnels weaken the tree limbs, which may break.