Half of the 250 species of described gall-inducing scale insects are eriococcids, and the vast majority of gall-inducing eriococcids are endemic to Australia, where they dominate the gall-inducing guild in much the same way that the gall wasps (Cynipidae) and gall midges (Cecidomyiidae) predominate in the northern hemisphere. The Opisthoscelis clade, a group of four genera feeding on Eucalyptus, is unusual amongst eriococcids in being comprised of some species that do not induce galls and others that induce galls of various complexities, ranging from simple pits to sexually dimorphic, enclosing structures. The phylogeny of the Opisthoscelis clade was reconstructed in order to test ideas about the evolution of gall induction within the group. Thirty exemplar taxa were included in a maximum parsimony analysis combining morphological data with sequence data from Wingless, 28S and 18S. We infer a single origin of gall-induction within the group, followed by multiple, independent transitions from simple to complex gall morphologies.