The ghost moth or ghost swift (''Hepialus humuli'') is a
moth
Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
of the family
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 Exop ...
. 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
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
...
.
The larva is whitish and
maggot
A maggot is the larva of a fly (order Diptera); it is applied in particular to the larvae of Brachycera flies, such as houseflies, cheese flies, and blowflies, rather than larvae of the Nematocera, such as mosquitoes and crane flies.
...
-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.
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.
Physiology and description
Female ghost moths have a wingspan of 50–70 mm. They have yellowish-buff
forewing
Insect wings are adult outgrowths of the insect exoskeleton that enable insects to fly. They are found on the second and third thoracic segments (the mesothorax and metathorax), and the two pairs are often referred to as the forewings and hindwi ...
s with darker linear markings and brown hindwings. Males are smaller, with a wingspan of 46–50 mm, and typically have white or silver wings.
However, in ''H. h. thulensis'', found in
Shetland and the
Faroe Islands
The Faroe Islands ( ), or simply the Faroes ( fo, Føroyar ; da, Færøerne ), are a North Atlantic island group and an autonomous territory of the Kingdom of Denmark.
They are located north-northwest of Scotland, and about halfway bet ...
, there are buff-coloured individuals.
Mating
Male/male interactions
Lekking
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.
Displaying
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
Sexual intercourse (or coitus or copulation) is a sexual activity typically involving the insertion and thrusting of the penis into the vagina for sexual pleasure or reproduction.Sexual intercourse most commonly means penile–vaginal penetr ...
.
Female/male interactions
Pheromones
Males perform a flight display and use both chemical and visual signals to attract females to their mating sites.
While aggregating in leks, male ghost swifts use
pheromones
A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
.. These are emitted in order to attract a female, but they are not known to be used as an
aphrodisiac
An aphrodisiac is a substance that increases sexual desire, sexual attraction, sexual pleasure, or sexual behavior. Substances range from a variety of plants, spices, foods, and synthetic chemicals. Natural aphrodisiacs like cannabis or cocai ...
. The main component of the male pheromone (in the distantly related species ''
Phymatopus hecta'') is
(''E'',''E'')-α-Farnesene.
The olfactory substances used to attract females are produced on the male's hind tibial brushes, and were said to be "goat-like", meaning the smell of the
Goat Moth
''Cossus cossus'', the goat moth, is a moth of the family Cossidae. It is found in Northern Africa, Asia and Europe.
Biology
This is a large heavy moth with a wingspan of 68–96 mm. The wings are greyish brown and marked with fine dark cr ...
caterpillar.
Males may also be attracted to stationary females by olfactory stimuli.
Sexual dimorphism
![Ghost Moth pair (7392024178)](https://upload.wikimedia.org/wikipedia/commons/1/10/Ghost_Moth_pair_%287392024178%29.jpg)
The ghost moth displays high levels of sexual
dichromatism (see picture right). Female ghost moths are a yellow brownish color, while males have silver/white wings. It has been suggested that the difference in wing color between males and females is used for visual epidemic signaling.
The upperside of males have un-pigmented scales with elaborate
morphology
Morphology, from the Greek and meaning "study of shape", may refer to:
Disciplines
* Morphology (archaeology), study of the shapes or forms of artifacts
* Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
and meshwork that allow for light reflection and may aid in attracting females.
The females lack the intricate morphology of the males. The underside of both the male and female ghost moth is a uniform grey/brown color.
It is believed that there is behavioral dimorphism as well, with one study showing that females were more attracted to light than males.
Predators
Common predators of ghost moths include several species of bats and birds. These predators are attracted to the moths during the male flight displays. ''
Eptesicus nilssonii'', the northern bat, has often been documented preying on lekking ghost moths. The ghost moth is a member of the family Hepialidae, an early branch of
Lepidoptera. Species in the Hepialidae lack several predator defense systems, including
ultrasonic hearing Ultrasonic hearing is a recognised auditory effect which allows humans to perceive sounds of a much higher frequency than would ordinarily be audible using the inner ear, usually by stimulation of the base of the cochlea through bone conduction. N ...
.
The ghost moth lacks sophisticated predator defense systems, and instead restricts its sexual behavior to a short period during dusk to reduce its predation risk. Despite these precautions, the moth is still at a large predation risk, especially at high latitudes where twilight is prolonged.
It is believed that the deaf moths, such as the family Hepialidae, pre-date the predatory bats that may have driven the evolution of ultrasonic hearing. It is currently believed that the ghost moth's restricted flight patterns and low flight positions may be their main form of anti-predator defense.
The ghost moth displays for only 20–30 minutes at dusk, which aids in predator avoidance, as most bats typically do not start feeding until after dusk, and most birds stop feeding well in advance of sunset.
Life history
Egg
On average, most female ghost moths will lay around 600 eggs over four days, but a female can lay anywhere from 200 to 1,600 eggs.
Larva
The ghost moth larvae grow up to 50 mm long and have a white opaque body with a red/brown head.
Their prothoracic plate is also red/brown, and their pinacula is dark brown. The young larvae feed on plant rootlets, while the older large feed on larger roots,
stolons, and the lower regions of plant stems.
The larval growth is very slow, and the developmental period can last for two to three years. The larva have at least 12
instars
An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...
, but further research is needed to see if there may be more instars during higher temperatures.
The larva cause damage to the plants they consume, with damage being the worst during the second summer of the larva's growth period.
The larvae typically feed in grasslands, lawns, and pastures and have been known to cause significant damage to the host species.
In the
British Isles
The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles, ...
, the ghost moth larvae live in the soil and can commonly be found underneath the grass.
Pupa
The ghost moth typically pupates during the April or May after the two to three year larval growth period has ended.
Adult
Adults are most commonly found in June and July, and they are typically active around dusk. In particular, lekking and mating occurs at dusk.
Damage to crops
Ghost moth larvae are
polyphagous—they are able to feed on multiple types of plants.
Larvae born on crops will typically feed on the roots and can cause significant damage to the crops. Ghost moths frequently cause damage to
strawberries,
lettuce
Lettuce (''Lactuca sativa'') is an annual plant of the family Asteraceae. It is most often grown as a leaf vegetable, but sometimes for its stem and seeds. Lettuce is most often used for salads, although it is also seen in other kinds of food, ...
, and
chrysanthemum plants.
Recorded food plants
Additional species which may be included in ''Hepialus''
Chinese authors retain a number of species in ''Hepialus''. Most of these are placed in the genus ''
Thitarodes'' by others. Species retained in ''Hepialus'' include:
Etymology
Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the Phonological chan ...
''Hepialus humuli'' was
first described by the Swedish
taxonomist
In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are give ...
,
Carl Linnaeus
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement in 1761 as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalise ...
in 1758. He named it ''Phalaena Noctua humuli '' — implying night moth of the hop vine. It was later allocated to the genus ''Hepialus'' (a fever), which was raised by
Johan Christian Fabricius
Johan Christian Fabricius (7 January 1745 – 3 March 1808) was a Danish zoologist, specialising in "Insecta", which at that time included all arthropods: insects, arachnids, crustaceans and others. He was a student of Carl Linnaeus, and is co ...
in 1775 and refers to its ″fitful, alternating flight″. The specific name ''humuli'' refers to the genus of hops (''
Humulus
''Humulus'', hop, is a small genus of flowering plants in the family Cannabaceae. The hop is native to temperate regions of the Northern Hemisphere. Hops are the female flowers (seed cones, strobiles) of the hop species '' H. lupulus''; as a main ...
''), on which Linnaeus wrongly thought, the larvae fed on its roots.
Subspecies
* ''Hepialus humuli humuli''
* ''Hepialus humuli thulensis''
Newman, 1865 (Great Britain, Faroe Islands)
Ghost moth in folklore
It is believed that the common name of "ghost moth" for ''Hepialus humuli'' may have originated from European
folklore
Folklore is shared by a particular group of people; it encompasses the traditions common to that culture, subculture or group. This includes oral traditions such as tales, legends, proverbs and jokes. They include material culture, ranging ...
, as there are numerous references to white moths being the souls of the departed.
It is believed that the ghost moth is also referenced in the last passage of
Wuthering Heights
''Wuthering Heights'' is an 1847 novel by Emily Brontë, initially published under her pen name Ellis Bell. It concerns two families of the landed gentry living on the West Yorkshire moors, the Earnshaws and the Lintons, and their turbulent re ...
by Emily Brontë.
[ Dead link]
Gallery
File:Faroe stamp 245 Hepialus humuli.jpg, Ghost moth on a Faroese stamp
File:Hepialus humuli f.jpg, Female
File:Hepialus humuli m.jpg, Male
File:Hepialus humuli, Ghost Moth, Trawscoed, North Wales, Nov 2013 (21418448681).jpg, Larva
References
*
Chinery, Michael
Michael Chinery (born 1938, in London
London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-e ...
(1986, reprinted 1991). ''Collins Guide to the Insects of Britain and Western Europe''.
*
Skinner, Bernard (1984). ''
The Colour Identification Guide to Moths of the British Isles''.
External links
*
''Lepiforum e.V.''
{{Taxonbar , from=Q476878
Hepialidae
Moths described in 1758
Moths of Europe
Taxa named by Carl Linnaeus