Small heath (butterfly)
The small heath is a butterfly species belonging to the family Nymphalidae, classified within the subfamily Satyrinae. It is the smallest butterfly in this subfamily. The small heath is diurnal and flies with a noticeable fluttering flight pattern near the ground. It rests with closed wings when not in flight. It is widespread in colonies throughout the grasslands of Eurasia and north-western Africa, preferring drier habitats than other Coenonympha, such as salt marshes, alpine meadows, wetlands, and grasslands near water. However, habitat loss caused by human activities has led to a decline in populations in some locations.
The larval host plants are grasses, found in various habitats, while adult butterflies feed on nectar from flowers. The males of this species are territorial, which plays a large role in obtaining a female mate. To establish dominance, they partake in lekking, a mating display in which males aggregate in a competitive display to attract passing females.
Taxonomy
The small heath is one of 40 species classified within the genus Coenonympha and placed in the family Nymphalidae. It belongs to the tribe Satyrini and its Coenonymphina subtribe. The small heath was first described in 1758 by Carl Linnaeus, a Swedish botanist and zoologist, in his book Systema Naturae. Originally, the female C. pamphilus butterfly was referred to as the Golden Heath Eye and the male as the Selvedged Heath Eye. Entomologist Moses Harris later described it as the Small Heath or the Gatekeeper. However, the Gatekeeper now describes the Pyronia tithonus.Description in Seitz
C. pamphilus. Small butterflies which on the upper side are the colour of reddish yellow sand. Forewing beneath reddish yellow, bordered with grey and bearing a small pupilled apical ocellus; hindwing diluted with grey, with a shortened, curved, whitish median band shaded with brown. The ocelli are generally completely absent or only indicated by faint and indistinct vestiges of dots or rings. — The ground-colour of the hindwing of the Northern form, pamphilus L. is mouse grey beneath; it is the only form in the North, and extends throughout North and Central Europe to Anterior Asia, Turkestan, Ferghana and Persia. — In ab. bipupillata Cosm. the apical ocellus is greatly enlarged and doubly pupilled. — marginata Stgr. has a very broad dark distal margin on all the wings, but its underside resembles that of lyllus. — lyllus Esp. is the summer form from Southern Europe, North Africa and the southern part of Anterior Asia. In this form the wings are broader, the apex of the forewing is more rounded, the margin of the hindwing often undulating, the underside of the hindwing not mouse-grey but also sandy yellow with a fine, curved, median line. — In Thyrsides Stgr., from Sicily-, Dalmatia and the southern portion of Anterior Asia, of which I also found typical specimens in the valleys of the Atlas, the hindwing on both sides bears a submarginal row of ocelli, which are sometimes pupilled. — Larva bright green with a thin, double, white dorsal stripe and yellow lateral one. Head pale green; throughout the summer on grasses. Pupa stout, green, with darker markings. The butterflies are the commonest Satyrids in the whole of Europe and are on the wing from the end of April until October, everywhere on meadows and fallow fields, cornfields and bare summits of hills. They almost fly only when disturbed, and soon settle again, affecting roads and bare patches of ground, sometimes inclining their always closed wings to one side. Their flight is jumping, slow, and low. They even fly into the towns, wandering over gardens and yards, and one sometimes sees them hopping along on paved streets for traffic, and settling for a moment on the pavement.Subspecies
of the Coenonympha pamphilus include:- C. p. lyllus
- C. p. marginata Heyne,
- C. p. fulvolactea Verity
- C. p. centralasiae Verity
- C. p. infrarasa Verity
- C. p. juldusica Verity
- C. p. ferghana Stauder
- C. p. nitidissima Verity
- C. p. asiaemontium Verity
- C. p. rhoumensis Harrison
Similar species
Distribution and habitat
The small heath is spread throughout the Western Palearctic, particularly in Europe where it has been reported in at least 40 different countries since 2002. It is commonly found in the United Kingdom, largely in England and Wales. Populations are also found in southwest Siberia, regions of Asia, and north Africa.As a grasslands species, the small heath prefers open habitats with shorter grass compared to other related species. It is also found in an extensive range of environments including meadows, heaths, mountains, and alongside railways. It has been sighted in calcareous grasslands throughout nineteen countries in Europe. For mating and oviposition, small heath butterflies prefer territories that are close to vegetation over areas that are open and clear.
The small heath also resides in biodiverse patches of green habitats in urban areas. These fragments create less-isolated corridors throughout cities, which help butterflies disperse throughout this habitat.
Food resources
Caterpillars
The primary food resources for small heath larvae are different varieties of grass species. These include the Anthoxanthum odoratum, Poa pratensis, Agrostis stolonifera, and Festuca rubra, which commonly appear on some calcareous grasslands.Adults
Adult small heath butterflies feed on floral nectar of a variety of flowers such as bramble, yarrow, and ragwort. This nectar has a high content of minerals and nutrients, and is highly important for male and female butterfly reproductive success.Parental care
Oviposition
The small heath is a plurivoltine butterfly, having multiple generations in a year. Oviposition varies throughout the lifespan of a female small heath. The rate of oviposition is high for young females, particularly at the beginning of their reproductive life, while older females eventually lay fewer and yellower eggs.Host plant selection for egg laying
Small heath females prefer to lay eggs in grassland. They use a biological adhesive to lay its eggs directly onto host plants, plants near host plants, or wilting leaves. If the eggs are laid on or near host plants, the larvae are able to feed on the host plant. If attached to the dead grasses, they are forced to find their own food immediately after hatching.Life cycle
Eggs
Small heath eggs are round and sometimes laid on blades of grass. The eggs are occasionally in clusters, but usually alone. Initially, the egg is a light green with a slight depression on the top and an overall ridged texture. It later gains a white hue with a brown band wrapped around the middle and irregular brown speckles on the surface.Egg color and weight changes throughout a female's lifespan. Younger females initially tend to lay heavier, greener eggs at a higher frequency. These eggs then transition to an intermediate green-yellow color. After about 100 eggs are laid, or near the end of their lifespans, older females lay lighter, yellow eggs. Adult small heath butterflies have at least one or usually two broods of offspring depending on environmental factors.
Larvae
Butterflies like the small heath typically undergo multiple stages of development called instars, through which the insect grows noticeably larger in size. The small heath typically goes through four instars and molts three times. The third instar signals a diapause in which the larva hibernates. By the end of the fourth instar, the small heath larvae are a leafy green color with a green stripe running along its back and stripes a lighter shade of green on its sides. It has pink anal points, a protrusion at the end of the caterpillar. Larvae will sometimes undergo a fifth instar and enter diapause, which possibly signals an adapted response to environmental factors. In diapause, the larva's resources are used to reinforce and strengthen its already-existing larval adult structures. These larvae then develop into larger male and smaller female pupae.Pupae
The small heath remains in the pupae stage for approximately 3 weeks. The color of the chrysalis fully develops in four days. The pupa is light yellow-green and suspends from a plant stem with the head facing downward. The cremaster is a series of hooks at the rear of the pupa, which allows it to hang from the stem. The pupae is thick and has a length of 8.5 mm. It is slightly curved with dark dorsal stripes around the sides and light-yellow bumps on the abdomen. The wing covers along the side are a white pigment with small accents of red-brown.Adult
The wings of an adult small heath butterfly are light brown. Males are darker and sometimes have gray-brown hues, while females are paler and occasionally a white-brown or yellow-white color. Other variations include a redder or yellower pigment with the occasional purple-brown color. Both males and females can have a brownish-gray border circling the edge of the wing. This border varies in thickness and appears to be more common in males than in females. The forewing can have a prominent or faint dark spot or, sometimes, no spot at all near the wing tip. The hindwings may also have eyespots or white dots. A white band runs along the underside of the wing and varies in width and fullness. Female small heath butterflies have a wingspan of 37 mm and tend to be larger than males, which have a wingspan of 33 mm.The small heath is diurnal, or is active in the daytime. It flies near the ground with a fluttering flight pattern. Small heaths are also lateral baskers, angling their bodies 90° to the sun with their wings closed when resting.