The second controlling environmental factor is the obvious characteristics of the olives and the phenological stage of the plant. Females receive sensory stimuli to denote the degree of receptivity of the olive, a phenomenon that allows them to choose the olive; before oviposition, the female first "analyses" the size, colour and odour and, it seems, the presence of certain bacterial species. They are especially frequent in summer, caused by the females with a sterile puncture to test the receptivity of the olive. The ethology of the fly has been paid particularly regard in recent years when analysing study control methods based on the use of prior insect repellents (copper, kaolin, etc.).