Abstract
Homozygous second chromosome lines were extracted from a natural population ofDrosophila melanogaster and tested for their olfactory responses to ethyl acetate. The chromosome lines were highly heterogeneous for this behavior, and the variability was also specific to other esters and ketones such as ethyl propionate, 2-butanone, 2-pentanone, and 3-pentanone. The responses to these odorants negatively correlated with the response to another odorant, lactic acid. A large part of this odorant-specific variation seemed to be controlled by genes located on the right arm of the second chromosome.