Host–parasite interactions are predicted to drive the evolution of defenses and counter‐defenses, but the ability of either partner to adapt depends on new and advantageous traits arising. The loss of male song in Hawaiian field crickets (Teleogryllus oceanicus) subject to fatal parasitism by eavesdropping flies (Ormia ochracea) is a textbook example of rapid evolution in one such arms race (Dugatkin 2008). Male crickets ordinarily sing to attract females by rubbing their forewings together, which produces sound by exciting acoustic resonating structures formed from modified wing veins (normal‐wing, Nw; Fig. 1A). The resulting song is the target of strong sexual selection by conspecific females. However, in Hawaii, male song also attracts female flies that squirt larvae onto males or nearby female crickets; the larvae then burrow into, consume, and ultimately kill the host. The flies thus impose strong natural selection on male song.