Most homozygotes survive to adulthood, although at a lower frequency than heterozygous siblings. Many homozygotes derived from heterozygous parents have melanotic tumours and abnormalities affecting the wings and/or bristles. Most affected flies have severe wing defects similar to a 'gnarled' or 'wrinkled' phenotype, while others have wing blisters or burnt 'notched' wings. 8% of flies have melanotic tumours inside the body. Among flies with extra bristles, most have one extra anterior scutellar bristle, while a few have two extra anterior scutellar bristles and/or an extra posterior scutellar bristle. Homozygotes derived from homozygous parents have impaired viability and fecundity and have an increased penetrance and expression of similar defects to those seen in homozygotes derived from heterozygous parents.