Unlike the emperor in the Hans Christian Andersen story, Emperor Moths are gorgeously clad with no need to hire any tailors, deceptive or otherwise.
Being the largest moths – and also the largest insects – in the world, Emperor Moths are not only impressive in size, but also they are beautifully marked with striking colouration. The wingspan of the largest Emperor Moths in Africa can be up to 180 mm.
In our garden, I came across a fairly large (wingspan up to about 130 mm) Speckled Emperor Moth (Gynanisa maja). This species can be found in many countries in Africa as far north as Chad, and in several countries in western, central, eastern and southern Africa.
All Emperor Moths are “furry”, and the Speckled Emperor Moth particularly so, as can be seen in these photos taken of one individual resting during the day on a wall in our garden
Emperor Moths belong to the family Saturnidae, with the name relating to the concentric rings of the planet Saturn and referring to the ring-like eyespots that many Emperor Moth species have on their wings. At rest the forewings cover the eyespots on the hind wings, but if disturbed, the moths quickly lift the forewings to suddenly reveal the eyespots, which may frighten off would-be predators.
As can be seen in this photograph of a Speckled Emperor Moth, the eyespots on the forewings are small and dull, and the larger and colourful eyespots on the hindwings are just visible, partly concealed by the forewings
Emperor Moths can be found in many countries around the world, with most occurring in the tropical regions. They are mostly nocturnal, flying late at night and are reluctant to fly during the day, even when disturbed.
But when and what do they eat, you may ask? The answer is: nothing. In their adult (moth) form they do not eat at all, and their mouth parts are so small that they are actually incapable of eating. The moths live from three to five days, long enough to breed and short enough for their “clothing” to always be new. The males die after mating and the females die after laying their eggs.
Emperor moth larvae (caterpillars) do the eating, and most eat foliage. Some species of these caterpillars burrow into the ground as a protection from predators, to pupate before hatching as moths.
Perhaps the most famous African Emperor Moth caterpillars are those known as Mopane “worms” (Gonimbrasia belina), which are a popular food source for people in some regions of southern Africa, where the caterpillars can be a cheap source of protein. The caterpillars are picked in the wild, degutted and then they are dried to preserve them. They can be rehydrated before cooking. In some areas in a good harvest season, cooked Mopane worms are canned.
Generally the females are larger than the males, though males have more feathery antennae than the females. I would guess that this individual is a female. In this photo, the fine antennae are just visible as they are being held along the edges of the forewings, on either side of the head
In Africa, most Emperor Moths are found in open country, with only a few species found in arid regions and even fewer in forests. There is one southern African species that has adapted to pine and bluegum plantations where the larvae are considered a pest.
The females lay eggs even if they have not mated, and mostly these unfertilised eggs do not hatch, but amazingly in one of the subspecies, eggs laid by females that have not mated do hatch and the offspring develop normally, a process known as parthenogenesis.
Pictured above is another beautiful Emperor moth that I was able to photograph in our garden. Like the Speckled Emperor Moth, it was also resting during the day on a wall in the shade. It is a Southern Marbled Emperor (Heniocha apollonia). Its range is restricted to the countries of southern Africa
Sources: Pinhey, E. 1972. Emperor Moths of South and South-Central Africa. Cape Town: Struik; Scholtz, C.H. and Holm, E. 1985. Insects of Southern Africa. Durban: Butterworths.
Posted by Carol