Saissetia oleae

Saissetia oleae (syn. Coccus oleae) is a scale insect in the family Coccidae. It is considered one of the three main phytophagous parasites of the olive tree (Olea europaea), together with the olive fruit fly (Bactrocera oleae) and the olive moth (Prays oleae). Although it is a common parasite which occurs most often in olive trees, it is a polyphagous species, also attacking (but less frequently) citrus trees as well as various ornamental shrubs such as oleanders, pittosporums, sago palm, and euonymus.

from Wikipedia