Piwi-interacting RNA (piRNA) is an evolutionarily conserved class of small RNA that is responsible for silencing transposon mRNAs in the gonad. They are made from RNA transcribed at distinct genomic loci called piRNA clusters. The cluster-derived RNA is exported to the cytoplasm and cleaved into piRNAs by a combination of endo- and exonucleases. The most deeply conserved mode of biogenesis is called ping-pong. Ping-pong involves two Argonaute proteins that cleave RNAs from sense and anti-sense strands of the same sequence. Because sense piRNAs produce anti-sense piRNAs and vice versa to amplify each other's pool, ping-pong mechanism is considered integral to robust and abundant piRNA production. Indeed, all animals that are known to possess piRNAs carry out ping-pong to produce piRNAs. Here we report that one species of Drosophila, Drosophila eugracilis produces abundant piRNAs without ping-pong. They do so by entirely relying on the other piRNA biogenesis mechanism called phasing. We discuss what drove the loss of ping-pong mechanism and how the transposon silencing works without it.