During an Ecotraining course at Selati Game reserve in November 2009, we came across a Mopane moth (Gonimbrasia belina) on one of our morning walks. Because Mopane worms (the larvae of the Mopane moth) is so well known, Albie Venter, the guide, and myself proceeded to tell the rest of the group something about the moths. As I was explaining what the differences between male and female antennae are, I suddenly got confused. The specimen we had in our hands, had one feathery antenna... and one smooth one? So we thought it must be a male with a damaged antenna... but it also had eggs attached to it. And then we realised, as if we were hit by lightning, that the specimen we were holding is actually a gynandromorph – a single organism where the one half of the specimen is male and the other half is female. A once in a lifetime find and the dream of many Lepidopterists! In most emperor moths, males have feathery antennae to pick up the pheromones produced by females. The females only have very slight feathering on their antennae. In Mopane moths, there are very few differences between the wings of males and females, but in other species, gynandromorphs can be quite intriguing as part of the wing colouration looks like that of a male, and the rest looks like the female.
So a dull, half-dead moth that could have easily been overlooked, turned into one of the highlights for the year and contributed just a little bit more towards our knowledge of the secretive night flying insects!
Written by Andre Coetzer