Mass trapping is a technique based on the reduction of pest populations in the field by placing a high density of traps. These devices contain a food attractant to attract insects and a toxic that causes their death. This technique has shown its effectiveness in the control of various tephritid insects, such as the olive fly (Bactrocera oleae). The technique has shown a high persistence and the crops are protected for long periods. However, while this technique is applied, it needs to be monitored to ensure its efficacy. In case that during the months in which it is set in the field, the treatment threshold is exceeded, it would be necessary to apply a support foliar treatment. Its efficacy is monitored by assessing the insect populations and the damage caused by the olive fruit fly. To assess insect populations are used both the mass- trapping devices and additional pheromone traps. Ten 10 mass- trapping traps per hectare are randomly selected and the number of individuals of each sex of B. oleae caught is counted monthly.

Three yellow sticky-traps with pheromone per hectare are also set and the number of caught individuals is assessed with the same frequency. Both sexes are easily distinguished by the presence of the ovipositor in female individuals. Regarding olive damage, 10 olives per tree are sampled, in 20 trees per hectare. Olive fruits that show symptoms of being attacked are dissected in the laboratory to determine the stage of development of the insect and accurately determine the phenology of the pest.