Chocolate grass yellow (Eurema sari)

Chocolate grass yellow (Eurema sari) is a species of butterfly in Pieridae. It is a bright yellow butterfly, resembling the color of sulfur, with a wingspan of 36-42 mm and brown-tipped forewings. Its wings are a vibrant yellow, adorned with several spots.

On the upperside, the wings are a deep lemon-yellow, each featuring a black border that is regularly scalloped and deeply indented between veins 2 and 4 on the forewings. On the underside, the wings are yellow with brown spots. A cell spot near the tip of the forewing is entirely dark brown. Males possess a "brand" (a patch of specialized scales) along the cubital vein on the underside of the forewings.



Eggs are laid singly on the leaves of host plants. Occasionally, multiple eggs may be found on a single leaf, resulting from repeated visits by several female butterflies. Each egg is 1.4 mm long and stands upright on one end. The eggs are whitish and feature faint vertical ridges. A micropyle—a tiny opening for sperm entry—is located at the top end of the egg.

The eggs take 2.5–3 days to hatch. The larvae are cylindrical and 2.4 mm long, with pale white head capsules; they are covered in rows of tubercles along their dorso-lateral and lateral sides, extending the length of the body. Each tubercle bears a seta (hair-like structure) emerging from its center, with the tip of each seta shaped like a small droplet of water.

Upon hatching, the young caterpillars consume their empty eggshells as their first meal before moving on to feed on the leaves. Their body color shifts to a yellowish-green. Within two days, they reach a length of 4.8 mm before molting into the second instar.

In the second instar, the body remains a yellowish-green color. The head capsule is yellow and features small tubercles from which setae emerge, similar to the surface of the body. A pale yellow stripe runs laterally along both sides of the body. This stage lasts approximately 1 day, with a body length of 7 mm.

The 3rd instar has a yellow head and a yellowish-green body. Many of the setae become progressively shorter. This stage lasts approximately 1–1.5 days, with a body length of 10–11 mm.

The 4th instar ranges in color from pale greenish to yellowish-green. The yellowish lateral bands turn whitish and become more distinct. This phase lasts 1–1.5 days, with a body length of 17 mm.

In the 5th instar, the whitish lateral bands appear wider and more pronounced. The tubercles, covered in numerous setae, stand out more clearly as they are a darker shade of green than the paler base color of the body. This phase lasts 3.5–4 days, with a body length of 30 mm. On the final day, the body shortens and turns green. The caterpillar stops feeding and settles near the base of the host plant's stem to spin a silk pad and a silk girdle. The posterior end is anchored to the silk pad by the prolegs. The caterpillar remains motionless.

Pupation occurs 0.5 days later. The yellowish-green pupa remains anchored, though the posterior end is now attached to the silk pad via the cremaster, replacing the prolegs. The pupa features a pointed head and sharply edged (keeled) wing pads. The body is almost entirely devoid of markings, save for a thin, pale brown stripe along the dorsal side. The pupa measures 19–20 mm in length.

After developing for approximately 5 days, the pupal cuticle becomes translucent as the developmental process within the pupal casing nears completion. The yellow coloration and dark margins on the upper side of the forewings begin to show through. The following day, the adult butterfly emerges from the pupal casing.

TAXON

Kingdom: Animalia
Phylum: Euarthropoda
Subphylum: Hexapoda
Class: Insecta
Subclass: Pterygota
Order: Lepidoptera
Superfamily: Papilionoidea
Family: Pieridae
Subfamily: Coliadinae
Tribe: Euremini
Subtribe: Euremina
Genus: Eurema Hübner (1819)
Species: Eurema sari Horsfield (1829)
Subspecies:
Eurema sari curiosa Swinhoe (1885) in India
Eurema sari obucola Fruhstorfer (1910) in southern Borneo, Natuna, Palawan
Eurema sari sari in Java
Eurema sari sodalis Moore (1886) in southern Burma, Peninsular Malaya, Singapore, Thailand, Indo-China, Sumatra, northern Borneo
Eurema sari thyreus Fruhstorfer (1910) in Enggano

SYNONYMS

Terias sari Horsfield (1829)
Terias sodalis Moore (1886)

VERNACULAR NAME

English: Chocolate grass yellow
Thai: ผีเสื้อเณรส่าหรี
Indonesia: Kupu-kupu sari
Java: Kupu sari

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