This supporting online material provides detailed methods and supplementary data for the study of developmentally regulated piRNA clusters and their role in transposon control. The methods section outlines the procedures for antibody production, immunoprecipitation of Mili RNP complexes, small RNA cloning, Northern hybridization, and semi-quantitative RT-PCR. The supplementary figures and tables include analyses of piRNA distribution, methylation status, and the density of uniquely mapped piRNAs. The data show that piRNAs are highly specific to transposable elements, particularly SINE B1, L1, and IAP retrotransposons, and that their expression is developmentally regulated. The tables provide specific genomic locations and annotations of piRNA clusters, highlighting their association with various transposable elements.This supporting online material provides detailed methods and supplementary data for the study of developmentally regulated piRNA clusters and their role in transposon control. The methods section outlines the procedures for antibody production, immunoprecipitation of Mili RNP complexes, small RNA cloning, Northern hybridization, and semi-quantitative RT-PCR. The supplementary figures and tables include analyses of piRNA distribution, methylation status, and the density of uniquely mapped piRNAs. The data show that piRNAs are highly specific to transposable elements, particularly SINE B1, L1, and IAP retrotransposons, and that their expression is developmentally regulated. The tables provide specific genomic locations and annotations of piRNA clusters, highlighting their association with various transposable elements.