237. Eurema andersoni sadanobui (The One-spot Grass Yellow)

Number: 237

Family: Pieriidae
Sub-Family: Pieriinae

Species: Eurema andersoni sadanobui Shirôzu & Yata, 1982

Common name(s): The Anderson's Grass Yellow, The One-spot Grass Yellow

Photography location: Cuc Phuong N.P. (Ninh Binh Prov.), Ba Vi N.P. (Hanoi)

Monastyrskii & Devyatkin (2016) listed 9 Eurema species in Vietnam viz. brigitta, laeta, hecabe, blanda, andersoni, ada, simulatrix, novapallida and sari - the first six recorded in the North.

Eurema andersoni sadanobui is distributed, at least, from Thailand, Cambodia to Vietnam (N., C. and S.) whereas the nominate subspecies is limited to the southern part of Thailand and Burma, the Malay Peninsula and Sumatra.
This species appears to prefer semi-open areas and forest margins. It has narrower habitat requirements than E. hecabe or E. blanda, and is not encountered in gardens, wastelands, grasslands or agricultural fields like the latter two species. More often than not, specimens are encountered singly. They often display the peculiar habit of hiding on the underside of a leaf to rest upside down. 

Eurema andersoni can be separated from the other lookalike Eurema by a single large cell spot distinctly 3-shaped on forewing underside.

 Eurema andersoni sadanobui, Cuc Phuong - July 2013
Note hindwing distal margin evenly rounded (angulate at space 3 in E. hecabe)

Eurema andersoni sadanobui, Ba Vi foothills - December 2016
There is usually a dark brown sub-apical patch on the forewing (which can sometimes be very indistinct or even absent)

60. Eurema hecabe hecabe (The Common Grass Yellow)

Number: 60

Family: Pieriidae
Sub-Family: Pieriinae

Species: Eurema hecabe hecabe (Linnaeus, 1758)

Common name(s): The Common Grass Yellow

Photography location: Hanoi

Eurema species range from Asia, Africa, Australia, and Oceania, to the New World. At least 71 species are currently known. Monastyrskii & Devyatkin (2016) listed 9 Eurema species in Vietnam viz. brigitta, laeta, hecabe, simulatrix, blanda, andersoni, ada, novapallida and sari - the first six recorded in the North. 

Eurema hecabe is found across the entire African continent, throughout most of Asia south of the Himalayas, on most of the islands of the south Pacific, and across much of Australia. They have broad habitat preferences, ranging from agricultural fields, the open fringes of vegetated areas, shrubland to well wooded areas. Like other Grass Yellows, it is usually skittish and hard to photograph.

Underneath, there are typically two cell spots on the forewing - a characteristic that is mainly used to identify the lookalike species in the genus. However, some specimens could exhibit variations in which only one or no cell spots are present, as can be seen in the picture below.

Mating pair of Eurema hecabe
Note that the specimen on the left has two cell spots on the underside of the forewings, whereas the one on the right has just a minute spot. Note also the hindwing distal margin "angulated" (i.e. not evenly rounded) at space 3

57. Eurema blanda silhetana (The Three-Spot Grass Yellow).

Number: 57

Family: Pieriidae
Sub-Family: Pieriinae

Species: Eurema blanda silhetana (Wallace, 1867)

Common name(s): The Three-Spot Grass Yellow

Photography locations: Hanoi, Huu Lien N.R. (Lang Son Prov.), Lai Chau

Monastyrskii & Devyatkin (2016) listed 9 Eurema species in Vietnam viz. brigitta, laeta, hecabe, blanda, andersoni, ada, simulatrix, novapallida and sari - the first six recorded in the North.
The main differences between the species are a) the number of spots in the underside forewing cell, combined with b) the shape of the upperside forewing black markings and c) the shape of the apical area markings on the forewing underside. 

Eurema blanda probably rivals Eurema hecabe for the title as the most common Grass Yellow in Vietnam. Found in urban locations as well as forested areas.

Eurema blanda nectaring on Bidens flower (Hanoi suburbs/agricultural fields)
This species is unique in having three cell spots on the underside of the forewing

Another specimen from Hanoi suburbs also (November 2013)

Mating pair (Lai Chau, January 2017)

Streamside aggregation of puddling Eurema blanda and hecabe, Huu Lien N.R.