Hepialidae


The Hepialidae are a family of insects in the lepidopteran order. Moths of this family are often referred to as swift moths or ghost moths.

Taxonomy and systematics

The Hepialidae constitute by far the most diverse group of the infraorder Exoporia. The 60 genera contain at least 587 currently recognised species of these primitive moths worldwide. The genera Fraus, Gazoryctra, Afrotheora, and Antihepialus are considered to be the most primitive, containing four genera and about 51 species with a mostly relictual southern Gondwanan distribution and are currently separated from the Hepialidae sensu stricto which might form a natural, derived group. The most diverse genera are Oxycanus with 73 species, Endoclita with 60 species, Thitarodes with 51 species and Cibyra with 50 species following a comprehensive catalogue of Exoporia. The relationships of the many genera are not yet well established; see below for an ordered synonymic generic checklist, and the Taxobox for navigation.

Morphology and identification

The family Hepialidae is considered to be very primitive, with a number of structural differences to other moths including very short antennae and the lack of a functional proboscis or frenulum. Like other Exoporia the sperm is transferred to the egg by an external channel between the ostium and the ovipore. Other nonditrysian moths have a common cloaca. The moths are homoneurous with similar forewings and hindwings, and are sometimes included as 'honorary' members of the Macrolepidoptera, though archaic they are. Strictly speaking, they are phylogenetically too basal and constitute Microlepidoptera, although hepialids range from very small moths to a wingspan record of 250 mm in Zelotypia. Because of their sometimes large size and striking colour patterns, they have received more popular and taxonomic attention than most "micros". Many species display strong sexual dimorphism, with males smaller but more boldly marked than females, or at high elevation, females of Pharmacis and Aoraia show "brachypterous" wing reduction.

Distribution

Hepialidae are distributed on ancient landmasses worldwide except Antarctica but with the surprising exceptions of Madagascar, the Caribbean islands and in Africa, tropical West Africa. It remains to be borne out if these absences are real as Aenetus cohici was not long ago discovered in New Caledonia. In the Oriental and Neotropical regions hepialids have diversified in rainforest environments, but this not apparently the case in the Afrotropics. Hepialids mostly have low dispersive powers and do not occur on oceanic islands with the exception of Phassodes on Fiji and Western Samoa and a few species in Japan and Kurile Islands. Whilst the type locality of Eudalaca sanctahelena is from the remote island of St Helena, this is thought to be an error for South Africa.

Behaviour

Swift moths are crepuscular and some species form leks, also thought to have arisen independently in the genus Ogygioses. In most genera, males fly swiftly to virgin females that are calling with scent. In other genera, virgin females "assemble" upwind to displaying males, which emit a musky pheromone from scales on the metathoracic tibiae. In such cases of sex role reversal, there may be visual cues also: males of the European ghost swift are possibly the most frequently noticed species, being white, ghostly and conspicuous when forming a lek at dusk. Sometimes they hover singly as if suspended from a thread or flying in a figure of eight motion. The chemical structures of some pheromones have been analysed.

Biology

The female does not lay its eggs in a specific location but scatters them while in flight, sometimes in huge numbers. The maggot-like larvae feed in a variety of ways. Probably all Exoporia have concealed larvae, making silken tunnels in all manner of substrates. Some species feed on leaf litter, fungi, mosses, decaying vegetation, ferns, gymnosperms and a wide span of monocot and dicot plants. There is very little evidence of hostplant specialisation; whilst the South African species Leto venus is restricted to the tree Virgilia capensis this may be a case of "ecological monophagy". A few feed on foliage. Most feed underground on fine roots, at least in early instars and some then feed internally in tunnels in the stem or trunk of their hostplants. The has rows of dorsal spines on the abdominal segments as in other lower members of the Heteroneura.

Economic significance

Chinese medicine makes considerable use of the "mummies" collected of the caterpillar-attacking fungi Ophiocordyceps sinensis, and these can form an expensive ingredient. The witchetty grub is a popular food source especially among aboriginal Australians. In Central America and South America, hepialid larvae are also eaten. However, some species of Wiseana, Oncopera, Oxycanus, Fraus and Dalaca are considered pests of pastures in Australia, New Zealand, and South America.

Faunas

Fauna of Europe

Source and identification