There is no explicit definition of “ambrosia beetle”, but the following criteria are often used: 1) fungi represent the main source of the food consumed by ambrosia beetle larvae and adults, 2) the fungal symbiont or symbionts are non-random associates, transmitted by the beetles from one host to another and between generations, 3) the beetles are not able to survive and develop on a fungus-free diet composed only of plant tissue. A direct consequence of condition (1) is that larvae do not form their own feeding tunnels, although they may substantially participate in excavating a common breeding chamber or their own larval cradles. We do not consider strict feeding on fungi and the possession of mycangia to be defining characters of the symbiosis, since many exceptions exist.