This study investigated aspects of the ecology, pest status, and management of Nezara viridula (L.) in pecans in Australia. N. viridula adults were shown to feed in the pecan canopy from January to March, causing premature nut fall and black pitting of the kernel. N. viridula was shown not to be able to breed in pecans. Population increases of N. viridula occurred on uncultivated hosts (weeds) growing in the orchard understorey and surrounding vegetation, from which adults subsequently invaded the pecan trees. Mowing of understorey weeds was evaluated as a control measure for reducing N. viridula numbers in the orchard without the requirement for pesticide application. The action of natural enemies (parasitoids of eggs) was evaluated. Parasitism of eggs by Trissolcus basalis (Wolllaston) peaked at ≈54% during spring and summer. The results of this study are discussed in relation to the seasonal phenology of N. viridula on weed hosts in eastern Australia and the potential for management of N. viridula in other orchard crops.