Df(3L)BSC840 was isolated as a FLP recombinase-induced recombination event involving PBac{RB}CG11570e01503 and P{XP}d09934. The deletion was isolated as a chromosome carrying two copies of the miniwhite marker in progeny of w1118; P{hs-hid}3, Dr1/TM6C, Sb1 cu1 females crossed to P{hsFLP}1, y1 w1118; PBac{RB}CG11570e01503/P{XP}d09934 males. The 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{XP3.RB5}BSC840 from the segment of PBac{RB}CG11570e01503 to the left of its FRT site and the segment of P{XP}d09934 to the right of its FRT site. The breakpoints of Df(3L)BSC840 predicted from the Release 5 genomic coordinates of the transposable element insertion sites are  3L:11949919 ;12104338 and the cytological breakpoints predicted from these coordinates are 68E3;68F3. Df(3L)BSC840 failed to complement Df(3L)BSC395 and rols08232.