TI{CRIMIC.GT15} represents a DNA segment that has been inserted into the genome by homology directed repair using CRISPR/Cas9 in combination with a donor plasmid based on pM15. The inserted TI{CRIMIC.GT15} DNA is not flanked by transposable element ends and consists of a recombination-mediated cassette exchange (RMCE) cassette flanked by a pair of inverted attP sites. This cassette contains a mutagenic gene trap element consisting of a splice acceptor site, stop codons in all three reading frames and an SV40 polyadenylation signal. A w^SH00017.3xP3 marker allele is present downstream of the gene trap element. If the TI{CRIMIC.GT15} sequence is inserted into an intron of a native Drosophila gene of interest, the gene may be disrupted by the gene trap element. The w^SH00017.3xP3 allele acts as a dominant marker for flies that have incorporated the RMCE cassette; they can be identified by loss (or reduction) of red pigment in the eye. The attP flanked RMCE cassette in TI{CRIMIC.GT15} can be replaced with DNA from a compatible donor plasmid (where the sequence to be inserted is flanked by inverted attB sites) through recombination-mediated cassette exchange (RMCE) driven by the phiC31:int integrase.