A two year study conducted at the New Mexico State University at the Leyendecker Plant Science Research Center evaluated multispectral reflectance, nitrogen (N), water and insect interactions on Acala 1517-99 upland cotton Gossypium hirsutum (L). The objective of this study was to determine if N and water inputs, measured by multispectral reflectance, influence Lygus spp. densities. Reflectance data was calculated as a normalized difference vegetative index (NDVI) using a GreenSeeker® to establish indices to differentiate applications of N fertilizer at 45, 135 and 270-lb per acre, treatments of four, five and six irrigations, and Lygus spp. densities in 2003 and 2004. A high clearance vacuum collector was used to sample arthropods from treatment replications. There was a significant increase in Lygus spp. densities as N levels increased but no significant increase within irrigation effects. Most predaceous arthropods were not as responsive to changing levels of N as Lygus spp. NDVI readings corresponded to Lygus spp. densities. It may be possible to prevent Lygus spp. infestations from developing in vigorously growing cotton by optimizing N applications. Reflectance technology could be used to track cotton development and to optimize agronomic and arthropod management practices while reducing N and water use.