The  wild-type  dominant allele yields brown eyes in the moth Ephestia
   kuehniella  since  it  can  synthesize  a  precursor pigment molecule,
   kynurenine.  The  a  mutation  interrupts  synthesis of kynurenine and
   yields red eyes.

<LI> In an Aa x aa cross, the aa larvae exhibit wild-type brown eyes if
the  Aa  parent  is  female. These aa larvae gradually develop red
eyes as they grow into adults.
<li> The Aa oocyte contains sufficient kynurenine in the cytoplasm
to be distributed to the cells of young larvae, who start out
life  with  brown  eyes. As the pigment is diluted among many
cells as the larva grows, red eyes emerge.