Ghost moth | |
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Scientific classification | |
Kingdom: | Animalia |
Clade: | Euarthropoda |
Class: | Insecta |
Order: | Lepidoptera |
Family: | Hepialidae |
Genus: |
Hepialus Fabricius, 1775 |
Species: | H. humuli |
Binomial name | |
Hepialus humuli (Linnaeus, 1758) |
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Synonyms | |
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The ghost moth (Hepialus humuli), also known as the ghost swift, is a moth of the family Hepialidae. It is common throughout Europe, except for in the far south-east.
Female ghost moths are larger than males, and exhibit sexual dimorphism with their differences in size and wing color. The adults fly from June to August and are attracted to light. The species overwinters as a larva.
The term ghost moth is sometimes used as a general term for all Hepialids. The ghost moth gets its name from the hovering display flight of the male, sometimes slowly rising and falling, over open ground to attract females. In a suitable location several males may display together in a lek.
The larva is whitish and maggot-like and feeds underground on the roots of a variety of wild and cultivated plants (see list below). The species can be an economically significant pest in forest nurseries.
Female ghost moths have a wingspan of 50-70mm. They have yellowish-buff forewings with darker linear markings and brown hindwings. Males are smaller, with a wingspan of 46-50mm, and typically have white or silver wings. However, in H. h. thulensis, found in Shetland and the Faroe Islands, there are buff-coloured individuals.
The ghost swift aggregates in leks in order to attract female mates. Lekking occurs at dusk and typically lasts for 20–30 minutes. During the lekking period, incident light intensities between 10.0 and 2.0 lux have been found to increase the brightness contrast between the background (grass/plants) and male moths' silver/white wings. It is thus believed that the male wing color may have evolved as a secondary adaptation to aid in the moth's visibility.
The male ghost swifts display by hovering directly above vegetation, while occasionally shifting slowly horizontally. The displaying male only occasionally made vertical movements to shift display positions. Females are attracted to the displaying males in leks, and once a female chooses a male she will pass within a few centimeters of him. The male will follow the female, who will land and beat her wings, signaling that the male may approach her. The two moths will then copulate, and the male moth may return to the lek and display again afterwards.