Studies were conducted at four fields (two plant cane/first ratoon and two second ratoon/third ratoon fields) to investigate the spatial distributions of yellow leaf caused by Sugarcane yellow leaf virus (SCYLV) and its aphid vector, the sugarcane aphid, Melanaphis sacchari (Zehntner), in Louisiana from November 2001 - October 2003. Variance to mean ratios were computed for each location, and this analysis indicated that SCYLV infections were initially distributed randomly but subsequently became aggregated at a Rapides Parish plant cane/first ratoon field, but remained in a random pattern at a second/third ratoon field in Iberia Parish. In Iberville Parish, infections in a plant cane/first ratoon field began as random and progressed to an aggregated pattern. A second/third ratoon field, also in Iberville Parish, began and remained in an aggregated pattern. Spatial autocorrelation analysis indicated aggregation and randomness with respect to both virus infection and sugarcane aphid data. Population densities of the sugarcane aphid at each location in 2002 ranged from about one aphid to 130 aphids per four leaves, and in 2003, densities were between zero and 17 aphids per four leaves across all locations.