Females homozygous for tuh1h produce adult offspring with significantly more bristles than homozygous tuh1g or tuh1g/tuh1h females. Increased bristle number occurs in the head, thorax and anterior and posterior abdomen. tuh1h is completely recessive to tuh1g. The phenotype is temperature sensitive, with the difference in bristle number between the offspring of tuh1h and tuh1g homozygous females being greatest at 18oC. Flies homozygous for tuh1h develop significantly faster than flies heterozygous or homozygous for tuh1g at 18oC, although there is no significant difference in developmental time at 25oC.