The last time I attempted to photograph this master of silent ceremony, the retraction of the coremata (glandular structures that bear pheromone-signalling hair-pencils) was so swift that the capture was a mere shadow of its former expansiveness. Even this result is substantively less extended than its first sighting, but it is by far my best result yet.
Females pheromonally attract males from long distances, however, when the male is close enough to begin his courtship, he inflates his coremata with air or hemolymph to evert externally from the abdomen and fans pheromones of his own towards the female.
Pyrrolizidine alkaloids (PAs) are produced by plants that are very well represented in the Daintree Rainforest, as a defense mechanism against insect herbivores. Ingestion of these PAs by both caterpillars and adults of this moth species influences the size of the male’s coremata and the quantity and quality of the courtship pheromone.
It seems that the female is able to ascertain mating advantages from the particular qualities of the pheromone. PAs are packaged into the male’s spermatophore as a nuptial gift, providing female moths with chemical protection from predation, even if they lack PA’s from their own dietary intake. Some of these nuptial PAs are also transferred onto the eggs for similar protection from predation.