AbstractAfrica has undergone a progressive aridification during the last 20 My that presumably impacted organisms and fostered the evolution of life history adaptations. We test the hypothesis that shift to living in ant nests and feeding on ant brood by larvae of phyto‐predaceousLepidochrysopsbutterflies was an adaptive response to the aridification of Africa that facilitated the subsequent radiation of butterflies in this genus. Using anchored hybrid enrichment we constructed a time‐calibrated phylogeny forLepidochrysopsand its closest, non‐parasitic relatives in theEuchrysopssection (Poloyommatini). We estimated ancestral areas across the phylogeny with process‐based biogeographical models and diversification rates relying on time‐variable and clade‐heterogeneous birth‐death models. TheEuchrysopssection originated with the emerging Miombo woodlands about 22 million years ago (Mya) and spread to drier biomes as they became available in the late Miocene. The diversification of the non‐parasitic lineages decreased as aridification intensified around 10 Mya, culminating in diversity decline. In contrast, the diversification of the phyto‐predaceousLepidochrysopslineage proceeded rapidly from about 6.5 Mya when this unusual life history likely first evolved. The Miombo woodlands were the cradle for diversification of theEuchrysopssection, and our findings are consistent with the hypothesis that aridification during the Miocene selected for a phyto‐predaceous life history in species ofLepidochrysops, with ant nests likely providing caterpillars a safe refuge from fire and a source of food when vegetation was scarce.