Plagiotrochus quercusilicis (Fabricius, 1798)

Host plants. Israel: Q. calliprinos . Elsewhere: Q. ilex and Q. coccifera .

Life history. Known only from the leaf galls of the sexual generation, which are multi-chambered, fleshy, rigid, ovoid, up to 8 mm in diameter, occupying most of the leaf (Fig. 74). The galls are green when young, red when mature, with smooth and shiny surface.

Phenology. Galls begin to develop in March and adults emerge from them in April-May.

Distribution. Israel: Odem Forest, Mt. Meron, Pa’ar cave, Kfar Hahoresh, Tiv’on, Mt. Carmel, Zur Hadassa. Elsewhere: This is the most common and widespread species in the genus Plagiotrochus, with a circummediterranean distribution.

Comments. When young, the galls resemble those of Plagiotrochus australis Mayr on Q. ilex in the Western Mediterranean Region but P. australis galls are single-chambered whereas those of P. quercusilicis are multichambered. Sternlicht (1968b) referred to galls of this species as belonging to the sexual generation of Plagiotrichus kiefferianus Tavares, a species that has been synonymized under P. gallaeramulorum Boyer de Fonscolombe (Pujade-Villar 2005) . The possibility that P. quercusilicis and P. gallaeramulorum are synonymous was first suggested by Tavares (1926) and later by Nieves-Aldrey (2001) but without clear evidence.