A genetic screen allowing selection of new insertions on the autosomes was carried out. Mobilization of the P{lacW} element occurred in males carrying a w[-] allele and P{lacW} on the X chromosome, and P{Δ2-3}99B, a stable source of P transposase, on a marked third chromosome. F1 males exhibiting the mini-white phenotype were recovered and a line for each fertile F1 male was established. Only lines with lethal or semi-lethal insertions mapping to the third chromosome were selected. To identify pre-meiotic clusters, complementation tests were carried out between lines derived from F1 males recovered from the same dysgenic cross; ~600 clusters were identified and eliminated from the collection.

Markers in stocks (as originally submitted to the BDSC):w¹¹¹⁸.