Many environmental factors, including soil characteristics, are critically important for plants, herbivorous arthropods, and their interactions. Despite increasing evidence that soil salinity can drastically impact plants, little is known about how salinity affects the herbivorous arthropod pests feeding on those plants we investigated how soil salinity affects two major crop pests: the two spotted spider mite (Tetranychus urticae) feeding on corn and soybean and the soybean aphid (Aphis glycines) on soybean. We quantified the impact of salinity by measuring demographic characteristics and behavior of pests on plants grown in soil with various levels of salinity. Overall, both crop pests performed better as salinity increased. These studies suggest that salinity can be just as important for herbivores as it is for plants. Moreover, the negative effects of soil salinity on crop plants in agroecosystems may be further compounded by a greater risk of pest problems.