The rain over the weekend triggered the annual hatching of the Bardi moths, also known as Ghost moths or Rain moths. These moths belong to the family Hepialidae and are of the genus Trictena. This family is known as the Swift moths or Ghost moths, and they are very large moths ( we had ones up to 12cm long flapping against the window) whose larvae feed on the roots of natives such Eucalyptus, Acacia and Casuarina sp. Common names can be very confusing and I often hear people call them Goat Moths or even Bogong moths. These are very different families.
It would be romantic to think that they are a ‘sign’ of rain – unfortunately they hatch during the event – a bit late to use them as a predictor! However, I always see the mass hatching night as the sign that the Autumn break has arrived in earnest and its always a night in April in this part of the world.
Bardi Grubs is the common name given to grubs of various species that feed on tree roots, but certainly this moth larvae is one of the more commonly used species. The brown, papery shell can be seen poking out of the ground the night after the hatching. According to the fantastic website from the butterfly house (http://lepidoptera.butterflyhouse.com.au/hepi/atripal.html) this species holds the “world fecundity record” , for the greatest number of eggs being deposited by a non-social insect. One dissected female had 44,100 eggs. It is thought that they are laid in flight. We were able to observe the females shedding the little yellow eggs all over the veranda and in the kids hands. There are some great photos of Trictena atripalpis on this website, probably the species we are all seeing.
The tawny frogmouths and other owls enjoy the hatching very much, coming in to feast on them where they are attracted to the lights of the house. They look like they are worthwhile meal (unlike the Bogong Moth) and apparently they are recorded as a bush food used by indigenous people.