Eurema hecabe
Encyclopedia
The Large Grass Yellow or Common Grass Yellow (Eurema hecabe) is a small pierid
Pieridae
The Pieridae are a large family of butterflies with about 76 genera containing approximately 1,100 species, mostly from tropical Africa and Asia. Most pierid butterflies are white, yellow or orange in coloration, often with black spots...

 butterfly
Butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

 species found in Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 or Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

. They are found flying close to the ground and are found in open grass and scrub habitats. It is simply known as "the grass yellow" in parts of its range; the general term otherwise refers to the entire genus Eurema
Eurema
Eurema is a widespread genus of grass yellow butterflies in the family Pieridae.Species range from Asia, Africa, Australia, and Oceania, to the New World. The type species is the North American Barred Yellow ....

.

Description

See glossary
Glossary of Lepidopteran terms
This glossary describes the terms used in the formal descriptions of insect species, jargon used mostly by professionals or entomologist....

 for terminology used

The Common Grass Yellow exhibits seasonal polyphenism. The lepidopteran has a darker summer morph, triggered by a long day exceeding 13 hours in duration, while the shorter diurnal period of 12 hours or less induces a fairer morph in the post-monsoon period.

Wet-season form

Male

Upperside: yellow, variable in tint from sulphur to rich lemon-yellow according to locality with a light or heavy rainfall. Fore wing: apex and termen deep black, this colour continued narrowly along the costal margin to base of wing, near which it often becomes diffuse; the inner margin of the black area from costa to vein 4 very oblique and irregular, between veins 2 and 4 excavate on the inner side, this excavation outwardly rounded between the veins and inwardly toothed on vein 3; below vein 2 the black area is suddenly dilated into a square spot which occupies the whole of the tornal angle; the inner margin of this dilatation is variable, in the typical form slightly concave. Hind wing: terminal margin with a narrow black band which is attenuated anteriorly and posteriorly ; dorsal margin broadly paler than the ground-colour.

Underside : yellow, generally a slightly paler shade than that of the upperside, with the following reddish-brown markings. Fore wing: two small spots or specks in basal half of cell and a reniform spot or ring on the discocellulars. Hind wing: a slightly curved subbasal series of three small spots, an irregular slender ring or spot on the discocellulars, followed by a highly irregular, curved, transverse, discal series of spots or specks, some or all of which are often obsolescent. On both fore and hind wings the veins that attain the costal and terminal margins end in minute reddish-brown specks. Antenna greyish yellow, the club black; head, thorax and abdomen yellow, shaded with fuscous scales; beneath: the palpi, thorax and abdomen yellowish white. The sex-mark seen from above appears as a thickening of the basal half of the median vein on the fore wing.

Female

Upperside: Very similar to that of the male but without the sex-mark; the black areas on both fore and hind wings slightly broader, with the inner edge of the black terminal band on the hind wing often diffuse.

Underside: ground-colour and markings as in the male. Antennae, head, thorax and abdomen similarly coloured.

Dry-season form

Upperside: ground-colour and markings much as in wet-season specimens, the emargination on the inner side of the black area and the tornal dilatation on the fore wing similar. On the hind wing, in the great majority of individuals, the black terminal band is also similar, in a few it is narrower and diffuse inwardly in both sexes.

Underside: ground-colour similar to that in wet-season specimens, but in very many with a greater or less irroration of black scales over the yellow parts of the wing; the reddish-brown markings on both fore and hind wings are also similar, but the spots are larger, more clearly defined, darker, and therefore far more conspicuous. In addition, on the fore wing there is a preapical, very prominent, transverse, elongate spot or short bar or reddish brown extended downwards from the costa. This spot is irregular in shape and of variable width, but does not seem ever to spread outwards to the actual edge of the termen. In a few specimens there is also a small reddish-brown spot in interspace 1 near the tornus. Antennae, head, thorax and abdomen, and in the male the sex-mark, as in wet-season specimens.

Life cycle

Eggs are laid on Abrus precatorius, Acacia
Acacia
Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...

spp., Aeschynomene
Aeschynomene
Aeschynomene is a genus of flowering plants in the family Fabaceae. They are known commonly as jointvetches. These legumes are most common in warm regions and many species are aquatic...

spp., Albizzia spp. and numerous other Leguminosae, Euphorbiaceae and Cucurbitaceae species.

Studies suggest that the females can discriminate colours when choosing host plants for oviposition
Oviposition
Oviposition is the process of laying eggs by oviparous animals.Some arthropods, for example, lay their eggs with an organ called the ovipositor.Fish , amphibians, reptiles, birds and monetremata also lay eggs....

.

Larva: "Long, green, rough, cylindrical, or slightly depressed, with a large head."

Pupa: "Suspended by the tail and by a moderately long band; the abdominal segments are round, but the thorax is much compressed, the wing-cases uniting to form a deep sharp keel. The head-case terminates in a short pointed snout. Ordinarily the pupa is solitary and green, but sometimes on a twig in large numbers. Many Pierine and other larvae seek each others company at that time. Having selected a dead branch of some neighbouring bush, they acquired the colour of their surroundings as nearly all Pierine and Papilionine pupae do to a greater or less extent."

This species has been found to be parasitized by multiple strains of Wolbachia. These bacteria can alter the sex-ratios of the species.

External links

  • Images of life cycle of Eurema hecabe on Flickr.
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