Abstract The red gum lerp psyllid, G lycaspis brimblecombei Moore, has been introduced from A ustralia into several countries, mostly in the A mericas and E urope. It was first discovered in B razil in 2003 and has continued to spread there. Today, the species is a major pest in eucalypt plantations and often requires expensive control measures. Ecological modelling is used here to estimate the potential spread of G . brimblecombeii , worldwide and particularly in B razil, based on environmental variables from 502 records of G . brimblecombei around the world. Distribution data from A ustralia were obtained from the literature and recent field surveys. For the first time, G . brimblecombei is recorded from W estern A ustralia. Through the O penmodeller® program interface, 22 bioclimatic variables were used to test the efficacy of the following models: BIOCLIM , C limate S pace M odel, E nvelope S core, E nvironmental D istance, GARP with best subsets (new O penmodeller implementation), GARP new O penmodeller implementation, GARP best subsets ( D esktop GARP implementation), N iche M osaic and S upport V ector M achines. Among these models, E nvironmental D istance was the best predictor for the potential distribution of G . brimblecombei in new regions. Temperate areas appeared to be more favourable for G . brimblecombei . Regions with highest probability of occurrence in B razil, in hierarchical order are: the southern part of the A tlantic F orest, P ampa, C aatinga and C errado. This modelling procedure provides a useful tool that should be incorporated in future strategies for pest management in eucalypt plantations.