Current climate conditions in north-central Chile (25057'-32013'S,71043'-68°16'W)are characterized by increasing temperatures and decreasing rainfall. Global warming is expected to alter the hydrology and ecoclimatic characteristics of north-central basins with multiple effects, including changes in plant and arthropod phenology and biodiversity. Among these basins, the Elqui Valley (29°50'S, 70°52'W) stands out for its large population and the economic importance of tourism and agriculture. The taxonomic composition of agriculturally and medically important arthropods was studied in three locations in the Elqui Valley by manual capture of specimens and interviews with farmers, agricultural workers, and local leaders. Out of a total of 145 species of insects and 36 species of arachnids, 36 insects and 1 arachnid are considered pests and are known to attack one or more host plants. Four orders dominated the insect suryes: Coleoptera (31.3% of the total captured), Orthoptera (13.9%), Hymenoptera (9.3%), and Lepidoptera (13.4%). Some agriculturally important insects include Macrosiphum, Rhopalosiphum, Myzus (Aphididae), Coccus, Parthenolecanium, Saissetia (Coccidae) and Pseudococcus (Pseudococcidae). Some medically important species are those in the zoonotic genera Loxosceles, Latrodectus, Triatoma, and Mepraia. The study of agriculturally and medically important arthropods will improve the design of better of management plans to minimize the vulnerability of ecosystems to climate change.