Our preliminary molecular phylogenetic work on the aphid family, Aphidinae (Hemiptera: Sternorrhyncha) suggested that one of the three tribes, Pterocommatini, was nested within another tribe, Macrosiphini. In this study, greater taxon sampling and the addition of another gene confirmed this result, and identified several major lineages within Macrosiphini that conflicted with previous taxonomic subdivisions suggested by morphology. Relationships suggest episodes of rapid diversification, conservation of host shifts, and gains, losses, and re-gains of host alternation.