When stg^Scer\UAS.cHa is driven by Scer\GAL4^klu-G410, results in a loss of bristles, without any noticeable effect on the general morphology of the thorax. About 50% of microchaetae are missing. Furthermore, the remaining microchaetae are disorganised and the stereotyped pattern of rows is largely lost. The rate of loss of macrochaetae varies depending on position. Losses range from 95% for the aDC to 20% for th pNP, pSA, aSA and 10% for thr pDC and aPA. The few aDC that form are shorter than normal. In mutant imaginal discs, sensory organ precursor cells are absent. When stg^Scer\UAS.cHa is driven by Scer\GAL4^sca-537.4, a loss of microchaetae us also seen. In the case of macrochaetae, the rate of loss varied according to position: 72% of PSA, 65% of cDC, 35% of aNP and 22% of pNP are missing. When Scer\GAL4^αTub84B.PP is driven in clones by Scer\GAL4^αTub84B.PP, a loss of microchaetae is seen. When the clones included macrochaetae sites they were also missing, though this was only seen in large clones.