The gene pacman (pcm) in Drosophila melanogaster encodes the exoribonuclease XRN1, which is highly conserved across eukaryotes and is the only known cytoplasmic exoribonuclease that degrades RNA in the 5’ – 3’ direction. Hypomorphic mutations to pacman have previously been shown cause developmental phenotypes, particularly during wing and thorax development. The focus of this thesis was twofold. Firstly, to create a null pacman allele and associated control lines to further characterise the phenotypes of pcm. Two new alleles were created, one of which was amorphic (pcm14). pcm14 is 100% lethal, and flies die during pupation. The wing imaginal discs of pcm14 larvae are less than half the size of those in wild-type larvae at the same stage (3rd instar). It was also found that wing imaginal discs in the hypomorphic mutant pcm5 are significantly smaller than wild-type, by almost 20%. Therefore, pcm appears to play a role in cell proliferation or apoptosis during the growth of wing imaginal discs. Along with pcm14, a new deficiency that includes pcm was created using a DrosDel Rearrangement Screen. The 17,963bp Df(1)ED7452 deficiency is >13 times smaller than the two other publically available deficiencies that include pcm.