Andricus solitarius

Andricus solitarius (Fonscolombe, 1832)

Host plants. Israel: Q. boissieri. Elsewhere: Several oak species from section Quercus.

Life history. Both the sexual and asexual generations are known, but in Israel only old bud galls of the asexual generation were found and no adults were reared. These galls are conical, single-chambered swellings at the tips of branches, widest basally, with very long and pointed, sometimes curved apex, brown and woody when mature. The sexual generation is known from Europe to induce single-chambered catkin galls, which develop from the flower buds on a stunted inflorescence petiole (Docters van Leeuwen 1934). The base of the gall is surrounded by stunted anthers, filaments and a small circle of hairs.

Phenology. Old galls of the asexual generation were found in Israel in July. In Europe, galls of the sexual generation develop before the catkin elongates, mature in May, and adults emerge from them soon afterwards. Galls of the asexual generation become visible in June, mature at the end of summer, and adults emerge from them in October.

Distribution. Israel: Very rare, observed only twice on Mt. Hermon at 1500 m.a.s.l. and on Mt. Meron. Elsewhere: A widespread but usually uncommon species all over Europe, northwest Africa, Transcaucasia and Iran.