New Zealand ghost moths

Hepialidae, commonly known as ghost moths are a family of moths that are considered ‘primitive’ in that they have remained relatively unchanged for a long time. Unlike other groups of Lepidoptera such as the butterflies which have evolved with flowering plants and consume nectar allowing them to live longer, ghost moths are unable to utilise nectar as a food source. This results in ghost moths having very short lifespans – often just one night long. This is just the adult moths I am talking about though, as the caterpillars of some ghost moths can be very long lived. A great example of this is the puriri moth caterpillar which spends several years feeding. Initially on the forest floor on dead wood and lichens before boring into the trunks of trees such as the puriri tree and beech trees from which it emerges at night to feed on callus tissue (tissue produced by the plant in response to injury) growing around the tunnel entrance. The adult moths however are very short lived – probably just a couple of days if they are lucky. The reason for this is evident when you see them in the field. They seem to have very little control over their flight and are often heard before they are seen due to them crashing into objects on the forest floor. But this seems to work for them as despite the incredibly long time it takes for them to reach adulthood, the adult moths are found every year, often in very large numbers as I am sure some of you have experienced. I was lucky enough to experience this myself over the summer – I say lucky because the Puriri moth, which happens to be New Zealand largest moth is only found in the North Island. While light trapping (if you don’t know what this is – see my first blog) at the base of the Ruahine Range over the summer, over 70 of these elegant moths came in – all with slightly different wing colorations.

Pictures one and two. Two puriri moths I photographed in Hawkes Bay over the Summer.

Heloxycanus patricki is yet another fascinating endemic ghost moth. I was lucky enough to collect a few of these over the weekend when I was in Southland. This moth feeds on sphagnum moss and its habitat is now severely fragmented due to the drainage of its wetland habitat which is also under threat from fire and activities such as sphagnum mining. A lot less is known about this species then the puriri moth but we do know it spends a minimum of two years as a caterpillar. We know this because the adult moths are only seen on odd numbered years (2009,2011,2013 and so on) which might be why it was discovered as recently as 1979. Like a few other New Zealand ghost moths Heloxycanus patricki flies late, from April to June. These strategies may be useful for avoiding predators, parasites, parasitoids and disease. Due to the beautiful colouration and appeal of moths such as Heloxycanus patricki they are good advocacy tools to help preserve the beautiful southern wetlands which they need to survive – and are also home to other nice insects such as flightless crane-flies and ground weta which I saw in the weekend.

Pictures three and four. Heloxycanus patricki male (top) and female (bottom) photographed on sphagnum moss

Picture five. Heloxycanus patricki habitat.

Despite their ‘primitive’ appearance, ghost moths are a successful group and have remained relatively unchanged for a reason – their strategy works. A testament to this is the large numbers that are often seen in the field as well as the fact that several ghost moth species in the genus Wiseana are some of only a few native-insect agricultural pests.

If you wish to learn more about New Zealand ghost moths I recommend the Hepailidae fauna of New Zealand.  And if you wish to read more about the Puriri moth lifecycle then I recommend the paper below

Grehan J.R. 1987. Life cycle of a wood-borer Aenetus virescens (Lepidoptera: Hepialidae). New Zealand Journal of Zoology, 14, 209-217.

In case you didn’t know, the second moth in my first blog was also a ghost moth. We have an awsome ghost moth fauna here in New Zealand!