On soil food webs, arthropods are part of important functional groups. Recognize these arthropods
and understand its function in the ecosystem as well as the period of the day in which they are
actives, is essential to understand their roles. In the present work we intend to study the soil arthropods
diversity as well as the period of the day that are actives in three olive groves from the Northeast
of Portugal. Particular emphasis was given to the generalist predators that can attack olive fruit fly
pupae in soil. The work was carried out during the spring of 2006 and at a bi-weekly basis 25 pitfall
traps/grove were put during 12 hours both on day period (from 7:00am to 7:00pm) and on
night period (from 7:00 pm to 7:00 am). The collected individuals were sorted and identified. Five
classes of arthropods were found: Chilopoda, Malacostraca, Entognatha, Insecta and Arachnida.
Captures were numerically dominated by springtails. Arachnida and Insecta classes represented
about 20.4% and 9.0% respectively from the total captures. Among the predatory arthropods, the
most representative groups were Aranea and Opiliones from arachnids and Formicidae, Carabidae
and Staphylinidae from insects. On Formicidae, Tetramorium semilaeve Andre 1883, Tapinoma
nigerrimum (Nylander 1856) and Crematogaster scutellaris (Olivier, 1792) were the most representative
ant species. Arthropods have demonstrated preference for the day, with 74% of the total individuals
recovered in this period although richness and similarity have been similar between periods
