A Mob of Syntherata!

Denis Wilson noted that his lights were mobbed by the large saturniid moth, Opodiphthera helenae (White), the Helena Emperor Moth. At about the same time, we in the tropics, about 2000 km to the north of Robertson, NSW where Denis made his observations, had the same occurrence with a related moth, Syntherata janetta (White). The caterpillars of his moth feed on a wide range of trees but are most commonly associated with Gum Trees (Eucalyptus spp.)

Our moth is known from the Northern Territory and north Queensland south to central New South Wales. The caterpillars feed on a wide range of rainforest trees but eucalyptus is not one of them.

What could be the reason for the outbreak of these two moths at approximately the same time of year at localities so different and so far apart. Maybe it is associated with the phase of the moon (see the moon to the left!) or the fact that these moths emerge every spring at this time. Or, perhaps, the excessive wet period of last year was just what these species needed to provide abundant food plants that has led to the large numbers of adults on the move.

Below is a sample of males of S. janetta illustrating some of the variation distinctive of this species. Additional examples can be viewed on Buck Richardson's Kuranda Moth site.

The most common colour morph of S. janetta.




The least common colour morph of S. janetta.