Guest Lecture by Assoc Prof Yen Shen Horn

Guest Lecture by Assoc Prof Yen Shen Horn

Biological Mimicry of Moths, Spiders & Fishes : Opportunities, Challenges and Perspectives Based on Asian Fauna

On Saturday, 7 Nov 09, four ButterflyCircle members were invited to a guest lecture by Assoc Prof Yen Shen Horn of the Department of Biological Sciences, National Sun Yat Sen University in Kaohsiung, Taiwan. The invitation to this very interesting talk was courtesy of Dr Leong Tzi Ming of the National Parks Board. Dr Leong, an avid lepidopterist, has published many papers on the on-line version of the Raffles Bulletin, Nature in Singapore.

Held at the exhibition area of the Raffles Museum of Biodiversity in a rather informal setting, A/Prof Yen held the small audience engaged in a very informative talk that lasted for over one and a half hours.

A/P Yen first shared with the audience what he and his department are currently focusing, in terms of research projects. Whilst many of the topics are highly academic and research type, it also expanded my outlook towards the depth of research that many experts like A/P Yen was doing.

A slide showing the multiple origins of Papilio paris in Taiwan

He also discussed the hybridization zone and climatic features affecting Hypolimnas bolina. An intriguing point that he made about H. bolina also corresponded with what I'd always also wondered about this species - that the subspecies that occur in Singapore and Malaysia could well be different forms as well. Over the past two decades, we've found the return of the subspecies jacintha and appears to have overrun the more common subspecies bolina in recent years. In the mid 90's the latter subspecies was a lot more common, but now appears to be very much rarer, with the subspecies jacintha making more frequent appearances.

A/P Yen then went on to discuss the theory of mimicry as expounded by the early researchers, Henry Walter Bates (1825-1892) and Dr Fritz Muller (1821 - 1897), and also the theories of Edward Bagnall Poulton, who offered his own theories about mimicry during the same era.

The discussion covered aposematism and what A/P Yen mentioned about the general reference to warning colouration in public talks is quite true - that an organism that is inherently colourful or with a flashy display of colours, is not necessarily exhibiting the fact that it is poisonous.

Also very interesting, were the studies that A/P and his co-researchers did of the Jumping Spiders and their preference of preys in a controlled environment.

One of the slides also depicted the many day-flying moths that ButterflyCircle members often encounter when out in the field. These moths, largely from the family Chalcosiinae, are often the models for other Lepidoptera mimic for protection against predators. It is also interesting to see that many butterflies (and moths) look very much like many of the moth species from this family. Many good examples of both Batesian and Mullerian mimicry strategies are found amongst these species.

A/P Yen also shared some digital resources of Lepidoptera in Taiwan. A few of the URLs are shown in the slide below. There are also many other projects and resources indicated in A/P Yen's CV. A particularly interesting one is the database of Global Butterfly Names.

The talk ended with a lot of thought-provoking issues on Lepidoptera research and questions that remain unanswered in this very fascinating subject. As ButterflyCircle comprise of mainly amateurs and hobbyists, though with more than a fleeting interest in butterflies, there is definitely a lot more ground to cover , and mysteries to unravel in the world of our Flying Jewels.

A/P Yen, Dr Leong TM and the BC members then visited the Raffles Museum of Biodiversity Research's lepidoptera collection and spent some time sharing anecdotes and experiences about the butterflies and moths in the collection.

Text and Photos by Khew SK. Talk Poster courtesy of A/Prof Yen Shen Horn

Acknowledgments :

• Associate Professor Yen Shen Horn, National Sun Yat Sen University, Taiwan
• Dr Leong Tzi Ming, Conservation Division/National Parks Board
• Kelvin Lim, Curator, Raffles Museum of Biodiversity

References :

• Wikipedia Online

Life History of the Large Four-Line Blue

Life History of the Large Four-Line Blue (Nacaduba pactolus odon)

Butterfly Biodata:
Genus: Nacaduba Moore, 1881
Species: pactolus C. Felder, 1860
Subspecies: odon Fruhstorfer, 1916
Wingspan of Adult Butterfly: 32mm
Caterpillar Local Host Plants: Entada spiralis (Fabaceae)


A Large Four-Line Blue perching on a small branch in the nature reserve.

Physical Description of Adult Butterfly:

The Large Four-Line Blue belongs to the pavana sub-group (the Four-Line Blues) in the genus Nacaduba, thus it possesses the shared characteristics of lacking a basal pair of lines in the underside forewing cell. Above, the male is purplish blue with marginal black borders of about 1.0mm thick. The female is pale blue with distal portions almost whitish, and has broad black borders of about 3-4mm thick. Beneath, both sexes are greyish brown with a slight silky lustre and with the space between the post-discal straie being unicolourous and of the ground colour. The underside stripes are broader and more diffuse than the other members, with the exception of N. angusta, of the pavana sub-group. On each hindwing, there is an mid-sized orange-crowned tornal spot lightly speckled with bluish-green metalic scaling. Both sexes have a filamentous white-tipped tail at the end of vein 2 of the hindwing.

The upperside of a female Large Four-Line Blue.

Field Observations of Butterfly Behaviour:

Although there were a mere handful of sightings of individuals during one survey and 2-3 outings in the past few years, the re-discovery of this species was only recently nailed with an ID confirmation provided by Prof Konrad Fiedler. This species is uncommon in Singapore but adults have been sighted in multiple locations such as the Central Catchment Nature Reserve, Southern Ridges, western wasteland and an offshore island. The adult has an erratic but rapid flight, and typically makes its appearance in sunny weather. Encounters usually take place in sunlit spots with the adult sunbathing or flitting from perch to perch in the vicinity of its host plant.

Early Stages:

The only known local host plant, Entada spiralis, is a woody climber with bipinnate leaves, usually with 4 pairs in a pinna. This tree-topping vine can be found in the Central Catchment Nature Reserve and Southern Ridges. The early instars of the Large Four-Line Blue feed on soft tissues of the host plant such as young leaves, young stems, tendrils, and flower buds. Across its range of distribution, N. pactolus has been found to use only one plant genus (Entada) as larval host, thus it is a stenoligophagous species.

Young shoots of Entada spiralis.


Oviposition by Large Four-Line Blue females. Left: on the underside of a young leaf. Right: on flower buds.


A mother Large Four-Line Blue laying an egg on a young shoot of E. spiralis.

Eggs are laid on young shoots, flower buds and young leaves (underside) of the host plant. Each egg is pale yellowish green, circular and has a depressed micropylar area. The surface is criss-crossed with a network of ridges. Each egg has a diameter of about 0.4mm.

Two eggs of the Large Four-Line Blue. Diameter: 0.4-0.5mm.

It takes about 2 days for the egg to hatch. The young caterpillar consumes part of the egg shell to emerge. With a length of about 0.7-0.8mm, it has a pale yellowish green body with long setae (hairs) occurring dorsally and sub-spiracularly. The caterpillar assumes the typical woodlouse body shape as it grows. Both the diamond-shaped pro-thoracic shield and the anal plate are pale green.

1st instar caterpillar, early in this stage, length: 1mm.

The first instar lasts for 2 days and the body length reaches about 1.5mm before the moult to the 2nd instar. The long dorsal setae are absent in the 2nd instar caterpillar. The body is yellowish green and has coarser texture on its surface. The dorsum of the thorax is slightly depressed. The 2nd instar also lasts for 2 days and the caterpillar grows to a length of about 3.5mm.

2nd instar caterpillars, length: 2mm.

The 3rd instar caterpillar is still yellowish green but with a stronger emphasis in green. Faint markings in much paler yellow appear on both sides of the dorsal line. The body is also densely covered with short brown or transparent setae. Both dorsal nectary organ and tentacular organs are not unmarked and are barely distinguishable. The prothoracic shield is white with a slight greenish tinge.

3rd instar caterpillars, late in this stage, length: 6.5-7mm

After 3 days in the 3rd instar with the body length reaching a maximum about 7-8mm, the caterpillar moults to its final instar. The 4th instar caterpillar initially resembles the 3rd instar caterpillar closely. As the body grows larger in size, its colour assumes a much darker shade of green.

Two views of a 4th instar caterpillar, length: 13mm.


4th instar caterpillar. Left: Prothoracic shield; Right: Dorsal nectary organ (DNO) and
tentacular organs (TO).

The 4th instar lasts for 4 days and the body grows up to a length of about 13-14mm. On the last day of this stage, the caterpillar ceases food intake and its body shrinks in length. Once a pupation site is selected, the pre-pupatory caterpillar prepares for pupation by spinning silk threads to form a silk pad on the substrate. It then stations itself with a silk girdle across its thorax and with its rear end attached to the silk pad.

Two views of a pre-pupa of the Large Four-Line Blue

The next day, after 11-12 days of larval growth, pupation finally takes place. The pupa has the typical lycaenid shape, and is covered with short brown setae. Ground colour is pale brown, and mottled with dark brown spots of various sizes and shapes. Length of pupae: 9-10mm.

Two views of a fresh pupa of the Large Four-Line Blue

Five days later, the maturing pupa becomes increasingly darkened in the head, thorax and the wing pads. The blue patches on the forewing upperside are now noticeable through the pupal skin. The next day the adult butterfly emerges from the mature pupa.

Two views of a mature female pupa showing the markings on the forewing upperside in the wing pad.


A newly eclosed Large Four-Line Blue resting on its pupal case

References:

• The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
• Butterflies of Thailand, Pisuth Ek-Amnuay, 1st Edition, 2006
• Notes on Host Association and Immature Biology of Nacaduba pactolus hainani, Y-F Hsu et al, BioFormosa, 34 (2), 2004, pp.61-65.
  

Text by Horace Tan, Photos by Sunny Chir and Horace Tan

Butterfly of the Month - November 2009

Butterfly of the Month - November 2009
The Striped Albatross (Appias libythea olferna)

A mating pair of Striped Albatross (Appias libythea olferna)

Time flies! And the eleventh month of 2009 is now upon us. November heralds the beginning of a generally wet season for SouthEast Asian countries as the start of the North East monsoon months commence in the region. Usually rainy with strong winds, the final few months of the year is usually 'low season' for butterflies.

A female Striped Albatross on Bidens sp one of its favourite nectar flowers

However, due to the north-easterly winds that blow from up north, it's also the time of the year where ButterflyCircle members have observed "immigrants" that are stowaways on the winds that carry them from Malaysia. So in between the rainy days when there are the occasional days of sunshine, there could be interesting finds to celebrate!

A pair of Striped Albatross shares nectar from a flower of Bidens sp.

This month, we feature the humble and common Striped Albatross (Appias libythea olferna). This species, described as rare in the 1960's and 70's, originates from India, Sri Lanka and Burma where it is common. However, it became progressively more common in Malaysia and Singapore in later part of the 20th century.

A theory was that as land was cleared and roads opened, its host plant, Cleome rutidosperma, a weed of sorts, became more and more abundant. Usually, in a patch of cleared urban land, this is one of the first weeds to colonise the bare earth. This plant, also often called Wild Cat's Whiskers, is a caterpillar host plant to two other Pieridae species as well, besides the Striped Albatross. With the availability of the host plant, the species was able to spread easily, and is today a common urban butterfly - in Malaysia and Singapore.

Upperside of a male Striped Albatross

The Striped Albatross is a species that demonstrates sexual dimorphism. The male is white above, with a dentate black border. The undersides have dark dusted veins, and the hindwing basal area lightly marked with yellow. Females are heavily dusted with greyish yellow on both the upper and undersides, and the basal area of the hindwing below is generously marked with yellow.

Both sexes have semi-transparent compound eyes and rather hairy in the palpi area. The antennae are banded with black and white and prominently clubbed. All six legs are fully developed.

The butterfly is a fast and erratic flyer, the male more so than the female, and are very skittish. They are often best photographed when feeding on wildflowers, although they are still sensitive to movement and will take off at the slightest hint of danger. Photographers have to move very stealthily in order to get a good shot of this species.

A male Striped Albatross puddling at a footpath in an urban park

Males are occasionally encountered puddling at sandy stream banks and paths, usually tainted with animal urine or decomposing organic matter. Both sexes are more frequently encountered in urban parks and gardens and less frequently in the forested nature areas in Singapore. They prefer to fly in open plains on hot sunny days.

Text by Khew SK : Photos by Benedict Tay, Federick Ho, Henry Koh, Khew SK, Sum CM, Sunny Chir and Tan BJ

Of Saws and Teeth

Of Saws and Teeth
The Sawtooth Butterflies



I've always wondered about the English Common names of the two species from the genus Prioneris. These large and robust butterflies found in Malaysia, belong to the family Pieridae. The two species, Prioneris philonome themana is known as the RedSpot Sawtooth whilst its close relative Prioneris thestylis malaccana is called the Spotted Sawtooth.

A RedSpot Sawtooth puddling at Endau Rompin Nature Reserve, Malaysia

Both the species are large butterflies and resemble the Appias (Albatrosses) and the Delias (Jezebels), to which they are relatively related. However, the Sawtooths are powerful flyers and are fast on the wing.

Another RedSpot Sawtooth puddling on damp ground

Both species are white above with the veins blackened in the outer margin areas The RedSpot Sawtooth has the hindwing basal two-thirds yellow, with a small red basal patch. The veins are prominently darkened. Its cousin, the Spotted Sawtooth is similar but has the entire hindwing yellow.

A RedSpot Sawtooth and a Blue Jay puddling on a sandy river bank

The RedSpot Sawtooth is the more common of the two species, and is found in the forested areas of Malaysia, often puddling with other Pierids and Papilionids. The Spotted Sawtooth prefers higher elevations but also has the same propensity for puddling at damp sandy stream banks tainted with animal urine and other decomposing organic matter.

A Spotted Sawtooth puddling next to a Chocolate Albatross

Coming back to the common name of "Sawtooth", it only dawned on me when I enlarged a shot that I took of the Spotted Sawtooth during post-processing, and I noticed the costa (or the leading edge) of the forewing. In the highly magnified view, one can observe that the wing edge is actually serrated with a series of sharp 'teeth' like the blade of a saw!

A Spotted Sawtooth puddling on tainted sand at Fraser's Hill

So now we may have stumbled upon one of the possible reasons behind why the early English collectors christened these two butterflies with the name of "Sawtooth". Click on the photo below to get a larger view of the serrated forewing of the butterfly's wing and you can see the details of the saw-like edge.

Text by Khew SK : Photos by Khew SK ; LC Goh & Sunny Chir

Two Blues Make it 290

Two Blues Make it 290
Update to the Butterflies of Singapore Species Checklist


The Glistening Caerulean (Jamides elpis pseudelpis)

After our last re-discovery report on the Moth Butterfly, which raised the number of butterfly species found in Singapore to 288, this update adds on two more species to the Singapore Checklist. Both these Lycaenidae were originally listed in the database of species from the early authors based on their checklists found in Butterflies of the Malay Peninsula Edition 4 by Corbet & Pendlebury, and Butterflies of West Malaysia and Singapore by WA Fleming.

The Large Four Line Blue (Nacaduba pactolus odon)

The reference checklists in C&P4 and Fleming's books form the baseline species checklists for butterflies of West Malaysia and Singapore. The journal article "Updating The Butterflies of the Malay Peninsula" in the Malayan Nature Journal in 2006, Vol 59 Part I, pages 1-49 records some of the more recent revisions. The first draft of this article was produced by Col JN Eliot just before his untimely death on 11 Apr 2003. The article was edited, enlarged and prepared for final publication by Henry Barlow, Richard Eliot, Laurence G Kirton and RI Vane-Wright - all experts in the field of butterflies of the region. This journal article adds to the baseline checklists and updates the more recent finds in Malaysia and Singapore in the later part of the 20th century and from 2000-2005.

There has been some recent confusion in the number of species for Singapore, with various authors counting subspecies as well. Based on scientific taxonomic convention in documenting species checklists, this is obviously incorrect. A species is counted only once irrespective of how many subspecies it may have. There have also been uninformed amateurs who insist on using reference books which feature butterflies of other countries in the region e.g. Butterflies of Thailand by Pisuth Ek-Amnuay, to baseline Singapore's species. This is obviously incorrect and misleading. The Thai book, which is an excellent reference for Thailand's butterfly fauna, is obviously not appropriate if used to identify Malaysian or Singaporean butterflies, in particular subspecies.

Two Re-Discovered Lycaenids recorded

Recently, ButterflyCircle members re-discovered two species from the genus Jamides and Nacaduba. These two genera feature many lookalike species which are difficult to identify from field observations. Often, only with good photos and records of the early stages of the species can the species be positively identified.

These two genera feature a number of species from the baseline checklists that have hitherto not been completely re-discovered. This is not to say that some of these species have gone extinct in Singapore, but merely a case of the difficulty of identifying them without proper scientific rigour.

Jamides elpis pseudelpis (Glistening Caerulean)

A female Glistening Caerulean ovipositing on the flowers of Saraca cauliflora

The genus Jamides features a number of species that are similar in appearance and difficult to identify when the butterflies are in flight. Occasionally, individuals are encountered puddling, ovipositing or feeding where good photos are possible, and from these, further confirmation can be made of the identity of the species. Better still, if the early stages are recorded and the caterpillars bred to adulthood.

The male of the Glistening Caerulean (Jamides elpis pseudelpis) is described to be pale shining sky blue above, with the hindwing paler and the underside markings visible from above. The pale blue female has a more prominent black tornal spot which is sometimes faintly orange-crowned. This species belongs to the elpis sub-group of the Jamides, which is characterised by the post-discal band on the hindwing beneath being completely dislocated at vein 3.

Another female Glistening Caerulean ovipositing on an alternative host plant's flower buds

The species has a wingspan of about 27-30mm where the marginal border on the upperside a thread, and the hindwing bears no submarginal markings. The upperside forewing border of the female ends at the costa.



The Glistening Caerulean was re-discovered by ButterflyCircle member Sunny Chir, after reviewing a shot of a Jamides taken at an urban park, where females were observed ovipositing on the flowers of Saraca cauliflora with another closely- related species the Sky Blue (Jamides caeruleus caeruleus) whose caterpillars also feed on the same flowers.

The early stages were recorded by ButterflyCircle member Horace Tan, and will be subject of a future blog life history article.

The Large Four-Line Blue (Nacaduba pactolus odon)



The second rediscovery belongs to the genus Nacaduba - again another genus with many confusing lookalike species. When in flight, there is no way to distinguish the numerous species that exist in Singapore. However, this species' underside markings are unique enough to be able to render identification with a higher confidence if a well-taken photograph is available.



The Large Four Line Blue belongs to the pavana sub-group in the genus Nacaduba. This sub-group is characterised by the absence of the basal pair of lines on the forewing beneath. The Large Four Line Blue is described as the commonest species in the group, and where the underside stripes are broader and more diffuse that in any other species in the genus.

This shot of a puddling Large Four Line Blue was taken at Pulau Pawai, an SAF live firing island

The male of the Large Four Line Blue is purplish blue with marginal borders of about 1.0mm thick. The female is pale blue with the distal portions almost whitish , and with broad black marginal borders of about 3-4mm thick. On the underside, the space between the post-discal straie are unicolourous and of the ground colour. The species has a wingspan ranging from 29-32mm. Both the males and females have a filamentous white-tipped tail at vein 2 of the hindwing.



The Large Four Line Blue is a fast flyer, the male particularly so, but in the later hours of the day, it flies rapidly and perches on a favourite leaf or twig, returning time and again to the same perch after flying off.

With these two re-discoveries, the Singapore Butterfly Checklist now reaches 290 species. In a forthcoming update, we will feature four more species - one of which is a new taxon for Singapore to further add to the Singapore Checklist.

Text by Khew SK ; Photos by Bobby Mun, Federick Ho, Horace Tan, Khew SK, Robin Ngiam, Sunny Chir & Tan CP

Special Acknowledgments : Dr Laurence Kirton of Forest Research Institute of Malaysia for confirming the ID of Jamides elpis.

Life History of the No Brand Grass Yellow

Life History of the No Brand Grass Yellow (Eurema brigitta senna)

Butterfly Biodata:
Genus: Eurema Hübner, 1819
Species: brigitta Stoll, 1780
Subspecies: senna C. & R. Felder, 1865
Wingspan of Adult Butterfly: 28-45mm
Caterpillar Local Host Plants: Cassia mimosoides (Family: Leguminosae, Caesalpinoideae).


A No Brand Grass Yellow resting on its host plant.

Physical Description of Adult Butterfly:
Above, each of the deep lemon-yellow wings has a black border which is regularly scalloped The black border on the forewing is not deeply excavated between veins 2 and 4 as in the other species of the Eurema genus. Underneath, the wings are yellow with freckled brown spots, more on the hindwings than the forewings. There are no cell spots on the forewing - a characteristic that is mainly used to identify the lookalike species in the genus. Males do not have an elongated patch (the brand) above and below the basal portions of the cubital vein on the forewing. The underside of the females are more distinctive in that the hindwings are much paler yellow than the forewings.


A female No Brand Grass Yellow taking nectar. Note the paler hindiwng underside.


A male No Brand Grass Yellow taking nectar.

Field Observations of Butterfly Behaviour:
This species is uncommon in Singapore. It was recently re-discovered in an open patch of reclaimed land slated for development. The host plant is not commonly seen, and this may be the reason why this species was not observed for a long time in Singapore. At its natural habitat, the No Brand Grass Yellow fly in rather sizable numbers in the vicinity of the host plants. Typically on a sunny day, the adults can be seen fluttering in the nearby open grassy areas and feeding on wild flowers from time to time. This species has also been sighted in one area on Pulau Ubin.

Early Stages:
The host plant, Cassia mimosoides, is a sub-shrub up to 1.5m high with variable stems, usually puberulent with short curved hairs. Inflorescence is supra-axillary or axillary with one to three yellow flowers. The leaves are pinnate, 3-12cm long and 0.8-1.2cm wide. Each compound leaf has 30-60 pairs of leaflets, each of which is 3-10mm long. The early stages of the No Brand Grass Yellow feed on relatively young leaves of this host plant.

Host plant: Cassia mimosoides growing in a coastal wasteland.

A mating pair of the No Brand Grass Yellow.

The eggs of the No Brand Grass Yellow are laid singly at the upperside of a leaflet or the rachis (main vein of the compound leaf) of the host plant. The long spindle shaped egg is laid standing at one end with a length of about 1.1-1.2m. It is pale yellow in color and has many fine vertical ridges and numerous indistinct and intermittent horizontal ridge lines. The micropylar sits at the tip of the standing egg.


A female No Brand Grass Yellow ovipositing on the compound leaf of its host plant..

Eggs of the No Brand Grass Yellow : far and close-up views.

The egg takes about 2 days to hatch. The newly hatched has a length of about 1.4mm and has a pale yellow head capsule. It has a cylindrical and pale yellowish green body covered with rows of tubercles running lengthwise. Each tubercle has a setae emerging from the middle of it. The two rows of tubercles flanking the dorsal line are much larger with longer satae than the rest. A miniscule droplet of fluid can be found at the tip of each setae. It has been reasoned that the droplets contain chemicals which serve the purpose of repelling parasitic insects. The droplet-bearing setae is a feature present in all five instars of this species.


Two views of a newly hatched caterpillar of the No Brand Grass Yellow, length: 1.4mm.

After hatching, the young caterpillar eats the empty egg shell for its first meal, and then moves on to eat the young leaflets nearby. The growth is moderately paced and the body length reaches about 3.5mm in this 1st instar which lasts for 2.0-2.5 days.


Two view of a 1st instar caterpillar of the No Brand Grass Yellow, length 2.3mm.
Note the fluid droplets evident at the tips of most setae.


Two views of a late 1st Instar caterpillar hours before its moult, length: 3.3mm.

The setae on the 2nd instar caterpillar are proportionately shorter and greater in number. There is a faint dorsal line which is darker than the base color of pale green. A pale white to yellowish band runs laterally along each side of the body. The head capsule is still pale yellowish green. This instar lasts about 2-2.5 days with the body length reaching 5mm.


Two view of a 2nd instar caterpillar, length: 4.1mm

The 3rd instar caterpillar has a yellowish green body with a green head capsule. Its setae are again proportionately shorter compared to the previous instar. The dark dorsal line and the lateral white/yellowish bands, first appeared in the 2nd instar, have both become more distinct. This instar takes about 2-2.5 days to complete with body length reaching about 9mm.


Two views of 3rd instar caterpillar, early in this stage, length: 4.9mm


Two views of 3rd instar caterpillar, late in this stage, length: 8.8mm.

The appearance of the 4th instar caterpillar is little changed from that of the 3rd instar. The lateral bands take on a greater hint of yellow, thus creating a stronger contrast against the green base color. This instar lasts 2-2.5 days with body length reaching about 15mm.


Two views of a 4th instar caterpillar feeding on a leaflet, early in this stage, length: 9.5mm.


Two views of a 4th instar caterpillar, late in thie stage, length: 14mm

The caterpillars of the No Brand Grass Yellow are neat and meticulous eaters. Typically each caterpillar systematically devours all leaflets (30-60 pairs), one leaflet at a time, on a single compound leaf of Cassia mimosoides before moving on to the next. For each leaflet, a 4th instar or 5th instar caterpillar will methodically start with eating one half of the lamina from the base, and then finish the remaining half by eating from the distal end. The following video clip shows the 2nd half of an eating session on a leaflet by a 4th instar caterpillar.

The 5th and final instar caterpillar resembles the 4th instar caterpillar closely. The one visible change is in the lateral bands which have taken on a striking yellow coloration. The 5th instar lasts for 3-3.5 days, and the body length reaches up to 25mm.


Two views of a 5th instar caterpillar, newly moulted, length: 15mm.


Two views of a 5th instar caterpillar, length: 20mm.

On the last day of the 5th instar, the body of the caterpillar shortens and changes to a dull shade of dark green. It ceases feeding and comes to rest on the underside of a stem/stalk on the host plant. Here the caterpillar spins a silk pad and a silk girdle, with which the caterpillar soon become immobile in its pre-pupatory pose.

A pre-pupatory larva of the No Brand Grass Yellow on a stem of the host plant.
Note the silk girdle featured at the first 2-3 abdominal segments.
Also the posterior end is secured via graspers to to the silk pad on the stem.

Pupation takes place about 0.5 day later. The pupa secures itself with the same silk girdle as in the pre-pupal stage, but with cremaster replacing graspers in attaching the posterior end to the silk pad on the stem, The thorax of the pupa is compressed and the wing pads join to form a deep keel. The head of the pupa has a short pointed snout at its end. The green pupal body is speckled with dark brown to black spots and patches. Length of pupae: 18-19mm.

The pupation event at 2 times the actual speed. Note the crucial role of the silk girdle in supporting the pupating larva, and the attachment of the cremaster to the silk pad at the 2.47 time mark.

A pupa of the No Brand Grass Yellow.

A mature pupa of the No Brand Grass Yellow.
The now transparent wing pad show s the yellow forewing upperside with its black border.

After about 4 days of development, the pupal skin turns translucent as the development within the pupal case comes to an end. The yellow coloration and back borders on the forewing upperside are now discernible. The following day, the adult butterfly emerges from the pupal case.

A newly eclosed No Brand Grass Yellow drying its wings near its pupal case.


A female No Brand Grass Yellow drying its wings on its pupal case.

References:

• The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, The Malayan Nature Society.
• Butterflies of Thailand, Pisuth Ek-Amnuay, 1st Edition, 2006

Text by Horace Tan, Photos by Khew S K and Horace Tan

Parasitic Mites on Butterflies

Parasitic Mites on adult butterflies
What are they?


An Arhopala sp with a rather large mite attached to its eye

Occasionally, when out in the field photographing butterflies, members of ButterflyCircle encounter strange red globular attachments to adult butterflies - usually at the head or eye of the butterfly. Curious as to what these little critters are, I searched the internet and found that butterflies do fall victim to certain parasitic mites.


A Tailless Line Blue (Prosotas dubiosa lumpura) with a red mite attached to its head

Another Arhopala sp with a red mite attached to its head

Interestingly, the majority of these encounters affect the smaller butterflies in the Lycaeninae family, even though there are examples from the Riodinidae and Hesperiidae families. So far, we have not encountered these mites on the larger species of butterflies yet. Although theoretically, there should be no reason why these mites could not attach themselves to larger butterflies as well. But by far, there have been more observations of these mites on Arhopala spp than any other butterfly genus.


Parasitic mites on the thorax of a Marbled White in the UK © Adrian Hoskins

In his excellent and informative website Learn about Butterflies, ButterflyCircle member Adrian Hoskins wrote about these mites on the British butterfly the Marbled White (Melanargia galathea), and in the example shown, a number of these mites were attached to the thorax of the butterfly rather than the eye or head, as is the more common occurrence in Singapore. Adrian noted that these mites were of the species Trombidium breei and that "studies have shown that these mites are harmless to the butterfly, having no detectable effect on the flight performance, orientation ability or lifespan".


A parasitic mite on a Hesperiidae. Even fast-flying skippers cannot shake off its little red passenger.

It is interesting to learn that despite being parasitic in nature, these mites have little effect on the lifespan of the butterfly. However, it is not known if the mites found on butterflies here in Singapore are of the same species of mites. Perhaps if a reader of this blog who is an authority on mites may want to contribute his or her knowledge about what these little stowaways are and if they cause any harm to the host butterfly.


Close-up shot of a mite attached to the eye of an Arhopala sp

Indeed, where a butterfly is encountered with one of these mites attached to its eye or head, the flight of the butterfly did not seem abnormal, nor did the butterfly display any discomfort or make any attempt to remove the mite with its legs. These butterflies observed seemed to be able to carry out their normal activity like feeding and flying around without much hindrance.


A mite on the eye of a Branded Imperial (Eooxylides tharis distanti)

In two of the cases shown here, the mites are rather 'skinny' where the legs can be seen. It is not known if the mites actually grow fatter as it feeds off the butterfly or if these are of a different species of mites.


Parasitic mite on the eye of Abisara geza niya. Inset : Close up of the mite. Is this a different species from the fatter mites?

It is likely that these mites lurk on flowers and vegetation where these butterflies frequent, and are able to quickly attach themselves to the butterflies when they stop to rest or feed at flowers. However, why they appear to generally attach themselves to the head/eye region of the butterflies observed in Singapore remains a mystery.

The fact that most of the encounters over the years by ButterflyCircle members show this phenomenon of a single mite attached to a butterfly's head or eye appears to reflect the consistency in which this happens in the field here in Singapore.

Similar-looking mites also parasitise other invertebrates like the Harvestman as is shown at this link.

So when you're out there in the field, observing and photographing butterflies, keep a look out for these little red dots on the butterflies, and record your observations and findings. If you have any clue as to what these species of mites are or how they affect the butterflies that they parasatise upon, do share your views with us.

Text by Khew SK : Photos by Adrian Hoskins, Anthony Wong, Federick Ho, Jason Ng, Horace Tan, Simon Sng, Sum CM & Tan CP.