Lethality acts in the second larval instar. Overall morphology of Bolwig's organ and nerve are normal in mutant larvae. Wild type foraging larvae show strong tendency towards photonegativity in a "Darth Vader" light avoidance assay. Homozygous mutants are less photonegative and hemizygous mutants are photoneutral.
Transheterozygotes with βTub60D5 are viable but flightless, transheterozygotes with βTub60D1, βTub60D4 and βTub60DP126 are viable but sterile.
Allelic series of mutations: βTub60D2 > βTub60D3 > βTub60D10 > βTub60D9 = βTub60D6 > βTub60D8 = βTub60D7 > βTub60Dsk > βTub60D11 > βTub60D5 > βTub60D1 > βTub60D4 > βTub60DP126.