Df(2R)BSC885 was isolated as a FLP recombinase-induced recombination event involving P{XP}d03020 and PBac{RB}CG42672e00881. The deletion was isolated as a chromosome lacking miniwhite markers in progeny of P{hsFLP}1, y1 w1118; P{XP}d03020/PBac{RB}CG42672e00881 males crossed to w1118; P{hs-hid}2, wgSp-1/SM6a females. These males were heat shocked as larvae as described in Parks et al., Nature Genetics 36: 288-292, 2004 (FBrf0175003). This cross and crosses in preceding and succeeding generations maintained the original genetic background of the Exelixis insertion stocks (Thibault et al., Nature Genetics 36: 283-287, 2004; FBrf0175002). The recombination event generated the genetic element P+PBac{XP5.RB3}BSC885 from the segment of P{XP}d03020 to the left of its FRT site and the segment of PBac{RB}CG42672e00881 to the right of its FRT site. Its presence was verified using the PCR methods and primers described in Parks et al. with the substitution of the primer 5’-GCTTCTAAACGCTTACGCATAAACGATG-3’ for the RB3’ plus or RB3’ minus primer in the Hybrid PCR protocol in the Supplementary Methods. The breakpoints of Df(2R)BSC885 predicted from the Release 5 genomic coordinates of the transposable element insertion sites are  2R:17102728 ;17189303 and the cytological breakpoints predicted from these coordinates are 57D2;57D10. To confirm the presence of the deficiency, we showed that a 715 base pair fragment spanning the PBac{PB}CG30393c05001 (FBti0041196) insertion site could not be amplified from Df(2R)BSC822/PBac{PB}CG30393c05001 flies using primers 5’-CGCATGTTGTGGATGACCCAACC-3’ and 5’-GCGAGACAACCATCACATCAGTCCG-3’.