Results/Conclusions For the two leaf miners, Amauromyza maculosa and Liriomyza trifolii (Diptera: Agromyzidae), increased soil salinity and high densities of the competitor Trirhabda baccharidis resulted in significant decreases in density. Neither of these treatments affected the gall maker Neolasioptera lathami (Diptera: Cecidomyiidae). Mycorrhizal fungi increased the densities of all three herbivores, possibly by increasing foliar nitrogen levels. For the two leaf miners, there was evidence that mycorrhizae ameliorated the negative effects of salt stress. There was also evidence that high levels of competition dampened the positive effects of mycorrhizae on the two leaf miners.