Dll¹/Dll³ mutant larvae have malformed dorsal organs. Larvae exhibit a normal behavioural response to an attractive odorant.

Dll¹/Dll³ animals die as pharate adults. They show both a transformation of the antenna towards leg and distal truncations. What remains of antennal segment 3 resembles leg tissue and the arista is deleted. A complete loss of the tarsal segments and shortening of both the femur and tibia is seen in the legs.

Heterozygotes have a normal antenna at 29^oC. At 25^oC and 19^oC the antenna show transformation to leg; at 25^oC the base and part of the arista have an irregular number of bracted bristles, which are sometimes also present on the third antennal segment. At 19^oC the whole arista has bracted bristles and occasionally a complete distal claw. The bracted bristles are arranged in the same pattern as bristles on the mesothoracic tarsus; two black and blunt bracted bristles are located proximally and distally in all but the most distal tarsal segment. The transformations do not extend more proximally than the distal part of the third antennal segment. Homozygotes die during the first instar larval stage without any morphological abnormality. Dll¹ is lethal in combination with Df(2R)Dll4. Hemizygous embryos lack the antennal sense organ, maxillary sense organ and Keilin's organs and sometimes lack the H piece and labial sense organ. The temperature-sensitive period (TSP) for the homeotic phenotype extends from early embryogenesis until puparium formation, and the level of homeotic transformation depends on the length of time at the non-permissive temperature rather than the precise time at which the pulse is given. The TSP for the leg deletion phenotype is sharply defined at the end of the third instar larval period.

homozygous lethal L1 larval lethal normal morphology. Heterozygote shows antenna-to-leg transformation; entire arista and part of third antennal segment transformed to distal metathoracic leg structures. Expression temperature-sensitive; transformation complete at 19^oC; phenotype normal at 29^oC. Dll/Df(2R)Dll4 shows abnormal segmentation both dorsally and ventrally and loss of head structures; antennal, maxillary and labial segments affected. 'H' piece malformed or absent as are Keilin's organs in all three thoracic segments. Recessive to two doses of 60D-F. cold-sensitive