Arthropod abundances, seasonality, and defoliation were measured on tarbush (Flourensia cernua) in southern New Mexico during 1990 and 1991. The arthropod assemblage on this desert shrub was dominated by five species of sap-sucking herbivores, four species of chewing herbivores, two ants, parasitic Hymenoptera, and two spider families. Species richness and abundances were highest during late summer. Several taxa present in substantial numbers at budburst in spring may overwinter on, or rapidly discover, this resource. Defoliation was caused primarily by a chrysomelid beetle (Zygogramma tortuosa) and amounted to about 30% by late summer. The arthropod functional group organization (e.g., proportions of chewing and sap-sucking herbivores, predators and detritivores) on tarbush is similar to that measured on other shrub species using comparable techniques.