Abstract
Populations of flies were tested for their phototactic response in a maze with 14 choice points. Selections for positive and negative phototaxis established lines with different responses. The phototactic score of the F1and parental populations from a 7 × 7 diallel cross were determined. Calculations from diallel tables indicated that phototaxis is controlled by polygenes, that negative phototaxis was partially dominant and that there were indications of a reciprocal effect.