The arboreal species of spiders on saltcedar, Tamarix spp., at Big Spring, Howard County, TX, were surveyed to determine which species could pose a threat to the success of the biological control agent Diorhabda elongata (Brulle) (Coleoptera: Chrysomelidae). This resulted in a list of the spider genera and species found on tamarisk and some initial information on spider ecology in association with this weed tree. Of the 1,495 specimens of spiders collected above ground level during the 3 years of study at the site, 55 spider species in 15 families were found on saltcedar trees. The most abundant species of spiders were mapped to determine their habitat on the trees and in relation to other species. Orb-weavers (Araneidae) and jumping spiders (Salticidae) were the most diverse families, as well as being common, but mesh web-weavers (Dictynidae), while less diverse, were individually numerous. Only orb-weavers were observed to feed on D. elongata in the field.