31 March 2010

Where Have All the Butterflies Gone?

Where Have All the Butterflies Gone?

"Where have all the flowers gone?
Long time passing
Where have all the flowers gone?
Long time ago
Where have all the flowers gone?
Girls have picked them everyone
When will they ever learn?
When will they ever learn?"*
* (c)1955 folk classic song by Pete Seeger
(Videoclip of the song by the legendary folk singers, The Kingston Trio)

I was back in Penang over the weekend for a short family visit and also to participate in Qing Ming Festival (also known as All Souls' Day). I hadn't visited my grandparents' graves for many years now, and it was time to get back to some good ol' tradition (at least whenever I can).

The wildflowers and grasses at the cemetary were blowing in the early morning breeze as there were many families paying their respect to their loved ones, each person lost in their own pensive memories of good times gone by.

Where Have All the Butterflies Gone?

In my three days of stay in Penang, I noticed a strange absence of butterflies in the usual areas where I would expect to see them. In my parents' home garden, the grassy patches in the neighbourhood, all around town and the usual vegetated areas, and even at the open areas of Mount Erskine where my paternal grandparents' were laid to rest and where the graves were covered with wild flowers, weeds, renegade trees that sprung up out of nowhere. Zilch. Not a single butterfly in sight - not even the common Striped Albatrosses, Lesser Grass Blues or Common Grass Yellow!

The weather was excruciatingly hot - almost in the mid 30's (that's a sweltering 93 deg F!). A taste of global warming to come? But our butterfly friends' absence probably suggest that they too, cannot tolerate this unfriendly weather and may have taken off to the sanctuary of the forests and hills.

Outdoors, it was unbearable by late morning as temperatures soared. It was rather saddening to see the near absence of any butterflies all around town, and in places where I used to see them, even in recent years. Fortunately, though, the sunbirds and spiderhunters that frequent my home garden were still up and about and their early morning chirps still pervade the air.

As with most of my trips back to my hometown, I made a short trip to the Penang Butterfly Farm to visit my friends there. It is always nice to walk amongst our 'flying jewels' and to try to photograph any species that I've not taken a good shot of before.

A female Jacintha Eggfly that may be an undescribed new form in the breeding cage at Penang Butterfly Farm

The Technical Director at Penang Butterfly Farm showed me a curious female "form" of the Jacintha Eggfly that has more orange patches on her wings than is usual. The submarginal markings on the hindwing of this new form appear to be consistent with subspecies jacintha rather than subspecies bolina. As suggested in my earlier article on a possible new form of the female Jacintha eggfly, it appears that the variability of this butterfly continues to intrigue enthusiasts like us. Hence at the moment, PBF is breeding a number of the offspring of this new form to see if there will be more consistent appearance of this different coloured variety of this subspecies.

The months of Mar through July are considered good butterflying months in Malaysia and Singapore. In PBF's controlled environment, there was an abundance of many species and their caterpillars were bred in good numbers. However, I wonder if it were the same for the free-ranging butterfly species around the island?

A old friend, the Blue Branded King Crow (Euploea eunice leucogonis)

This visit, I encountered the Blue Branded King Crow (Euploea eunice leucogonis), a species that I've not seen for a long time. This rather large crow, which resembles a supersized Dwarf Crow, has rather unique behaviour as described in C&P4 - "... erratic in appearance ; it may be abundant in a locality for a few months, then disappear completely for a year or two before reappearing and becoming as common as before."

There were also a number of Pieridae flying around in the flight cage - Great Orange Tip, Chocolate Albatross, Orange Albatross, etc.

And so ended a short weekend trip back home. It was a relief to get back to Singapore's "cooler" temperatures. I hope the signs of climate change back in Penang is something temporary and will not have a permanent impact on the butterfly biodiversity there. We will see on my next trip back.

And the melancholic tune and haunting lyrics of Pete Seeger's song played over in my mind...

Text & Photos by Khew SK

27 March 2010

Life History of the Pitcher Blue

Life History of the Pitcher Blue (Virachola kessuma deliochus)

Butterfly Biodata:
Genus: Virahola Moore, 1881
Species: kessuma Horsfield, 1829
Sub-species: deliochus Hewitson, 1874

Wingspan of Adult Butterfly: 26mm
Caterpillar Local Host Plants:
Nepenthes gracilis (Nepenthaceae, common name: Slender Pitcher Plant), N. rafflesiana (Nepenthaceae, common name: Raffles' Pitcher Plant).

An adult Pitcher Blue perching on a wild flower in an open field in Southern Ridges.

A male Pitcher Blue on a perch.

A female Pitcher Blue on a leaf perch.

Physical Description of Adult Butterfly:
Above, the male has its forewing mostly black with a small basal patch of shining blue at the dorsum, its hindwing mostly shining blue with a black costal border and a pale brown dorsum. The female is duel pale blue with broad brown borders on both wings. Beneath, the wings are pale brown and marked with white striae in similar arrangement as for the Four-line blues (pavana group of Nacaduba spp.) but without basal striae in the hindwing. Each hindwing has a small tornal lobe, a prominent subtornal orange-crowned black spot in space 2, blue and green metallic scales in space 1b and a white-tipped filamentous tail at the end of vein 2.

The upperside of a female Pitcher Blue.

A female Pitcher Blue checking out a flower of the Common Asystasia.

Field Observations of Butterfly Behaviour:
The Pitcher Blue is rarely seen in Singapore due to the loss of habitat for its larval host plants to various industrial, commercial and housing development projects in the past decades. In recent times, the adults have been sighted rather infrequently in locations where small pockets of pitcher plants remain. Such sites include parts of the nature reserves, Southern Ridges and other scattered wastelands. The adults are fast fliers. They usually stay high up in the trees and only make occasional visits to flowers in the vicinity. With luck and perfect timings, a keen observer can find females making oviposition visits to seed pods of the pitcher plants.

A female Pitcher Blue sighted making a brief stop-over in a wasteland.

A female Pitcher Blue on a flower of Buah Cheri (Muntingia calabura).

A female Pitcher Blue perching on a flower.

Early Stages:
Of the two Nepenthes spp. recorded as local larval hosts, N. gracilis, is found to be more commonly utilized by the Pitcher Blue as it occurs in much greater numbers than N. rafflesiana in their common habitat. N. gracilis is shrubby with alternate leaves and climbs with twisting leaf-tendrils. A fully formed leaf composed of a petiole, a lanceolate or linear leaf blade, a tendril and a tubular pitcher which has a lightly swollen and shortly incurved base. The pitchers are typically green with occasional reddish tinge. The flowers occurs in racemes and the fruits in capsule form (seed pods).

Host plant: Nepenthes gracilis. Leaf and pitchers (left); A fructescence (right).

Host plant: Nepenthes rafflesiana. Leaf and pitchers (left); A fructescence (right).

The caterpillars of the Pitcher Blue feed on the maturing seeds within a seed pod after gaining entry through a hole bored on the side of the pod. When their body size allows, especially during first three instars, they will stay within the confine of the pod and devour all its contents. The act of boring into a pod and eating its contents is repeated many times during the larval stage. Moulting invariably takes place within a seed pod.

Several eggs of the Pitcher Blue found on one single fructescence of N. gracilis.
Look for a white dot on the tip of a seed pod.

Eggs of Pitcher Blue are typically laid singly, and rarely in pairs or triplets, on the stigma remnant of a seed pod. At times, eggs are laid at the lower portion of the seed pod near the calyx. It is not uncommon to see multiple egg-bearing seed pods on one single fructescence.

Close-up on egg-bearing seed pods of N. gracilis (Left) and N. rafflesiana (Right).

Empty egg shells on the stigma remnant of seed pods. Up to 3 eggs have been found
on a single pod.

The small egg is dome-shaped (about 0.8-0.9mm in diameter) with a depressed micropylar. The surface is covered with a reticulated pattern of intersecting raised ridges. When freshly laid, the egg is whitish with a yellowish green undertone.

Two views of an egg of the Pitcher Blue. Diameter: 0.8mm.

Each egg takes 3.5-4 days to hatch. The young caterpillar emerges after nibbling away sufficiently large portion of the egg shell. Measured at a length of about 1.1mm to 1.2mm, its pale yellowish brown body is cylindrical in shape, sporting long fine setae (particularly long for those anterior and posterior ones), a dark brown to black head capsule and a large and oval shaped prothoracic shield. A dark brown anal plate is also featured with a prominent black spot.

Two views of a newly hatched caterpillar boring into a seed pod, length: 1.1-1.2mm.

The newly hatched makes its way to the side of the egg-bearing seed pod and starts to bore into it. It stays within the seed pod and feeds on the developing seeds. After about 2 days of growth, it reaches about 3.5mm in length. It then lies dormant within the seed pod for its moult to the 2nd instar. One seed pod is usually sufficient to last the entire 1st instar.

Two views of a 1st instar caterpillar, day 2 in this stage, length: 2mm.

Two views of a 1st instar caterpillar in a seed pod with content nearly all eaten.
The pod was peeled opened to reveal the caterpillar. Length: 3.2mm.

Life History of the Pitcher Blue. Part 1 of 3: Egg to late 1st instar.

Covered with numerous dark setae, the body of the 2nd instar caterpillar is brown to reddish brown in color with moderately longer setae running laterally. The head capsule is yellowish brown in colour. The dark brown to black prothoracic shield is rather prominent, resembling a triangle with a long base and short height. The body is still more or less cylindrical with larger anterior segments. The growth in this stage brings the caterpillar to a length of about 5.5-6.0mm, and after about 2 days in this stage, it moults again.

Two views of a 2nd instar caterpillar boring into another seed pod, early in this stage, length: 4mm.

A 2nd instar caterpillar in a seed pod, late in this stage, length: 6mm.

The 3rd instar caterpillar has numerous short and fine body setae, again with longer setae laterally. The head capsule is yellowish brown. The large and prominent prothoracic shield is more angled and comes with a little tooth at its base. The base body color is reddish brown but with lighter coloration on the dorsum of middle body segments. The 3rd instar takes about 3 days to complete with the body length reaching about 9mm before the next moult.

Frontal views showing the head and prothoracic shield of caterpillars in
2nd instar (left) and 3rd instar (right).

Two views of a 3rd instar caterpillar boring into a seed pod. early in this stage, length: 5mm.

3rd instar caterpillars in cut-open seed pods, lengths: 7mm (top) and 9mm (bottom).

As in the 3rd instar, the 4th (and final) instar caterpillar has numerous body setae and long lateral setae. There are also two rows of long setae occuring dorso-laterally. The body color is reddish brown to wine red.

Two views of a 4th instar caterpillar boring into a seed pod, early in this stage, length: 8mm.

Two views of a 4th instar caterpillar boring into a seed pod, midway through this stage, length: 12mm.

One prominent change from the 3rd instar is seen in the prothoracic shield which has now become pale yellow in base colour with small black spots lying within and large black spot in its four corners. The dorsal nectary organ is rather prominent. It is functional as ants have been observed to attend to it for caterpillars found in the field.

The prothoracic shield (left) and the dorsal nectary organ (right) of a 4th instar caterpillar.

A 4th instar caterpillar attended to by an ant in its natural habitat.

On the last feeding day in this instar, the first two thoracic segments and 3rd to 5th abdominal segments becomes lighter in coloration (shades of yellow, orange and even beige), giving the caterpillar a distinct banded appearance.

4th instar caterpillars, late in this stage. Top: eating through a hole, length: 14mm.
Bottom: wandering for a pupation site, length: 15mm.

Life History of the Pitcher Blue. Part 2 of 3: 2nd to 4th instar.

After 4-5 days of growth and reaching a maximum length of around 15-16mm in the final instar, the body of the caterpillar gradually shrinks. The caterpillar ceases eating and wanders around for a pupation site. All bred specimens chose to enter their pre-pupatory phase on a spot of the leaf surface within a gape in a pile of leaf litter. At the chosen site, the caterpillar readies itself for pupation by spinning a silk girdle and a silk pad. In the wild, some caterpillars even choose to pupate within a pitcher.

Two views of an immobile pre-pupatory larva of the Pitcher Blue,
The silk girdle can be easily seen.

Pupation takes place after one day of the pre-pupal stage. The lightly hairy pupa has the typical lycaenid shape, light brown in base colour with variable number of black to dark brown patches on the pupal surface. The pupa of Pitcher Blue has silk girdles and is equipped with cremastral hooks to secure it to a silk pad on the substrate. The pupa has a length of about 9-10mm.

Two views of a pupa of the Pitcher Blue, length: 9.5mm

Eight days later, the pupa becomes darkened in color signaling the imminent emergence of the adult. Patches of green and blue can be seen in the wing pads through the now transparent pupa skin. The next day the adult butterfly emerges from the mature pupa.

Two views of a mature pupa of a male Pitcher Blue.

Life History of the Pitcher Blue. Part 3 of 3: Pupation and Eclosion.

A newly eclosed male Pitcher Blue drying its wings on a young fern frond.

  • 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.
  • A guide to the carnivorous plants of Singapore, edited by Hugh T. W. Tan, Singapore Science Centre, 1997.
Text by Horace Tan, Photos by Sunny Chir and Horace Tan

21 March 2010

Mergers, Partnerships & Betrayals

Mergers, Partnerships and Betrayals
The Miletinae - The Harvesters

A multi-tasking pair of Bigg's Brownie (Miletus biggsii biggsii) - mating & feeding amongst their protector ants

In the real corporate world, the title of this blog would probably not elicit much interest and excitement, other than offering a good read about yet another unfortunate company being swallowed up, or employees being thrust into a chasm of anxiety about their future.

A Bigg's Brownie (Miletus biggsii biggsii) feeding off what appears to be a "herd" of mealy bugs that are tended by their protector ants

In the world of Lepidoptera, however, the partnership between butterfly and ants is already a well-studied topic by entomologists. Myrmecophily, or the positive interspecies association between ants and butterflies (or rather, their caterpillars) has been widely studied. This symbiotic association occurs with some Lycaenidae caterpillars evolving specialised organs that exude honeydew in return for protection by the ants. These caterpillars then go about their daily business of feeding on the leaves of their host plants, whilst enjoying 'armed' guards' protection from predators.

However, there exists a subfamily within the Lycaenidae family - the Miletinae, that is unique in the sense that their caterpillars are predatory or "carnivorous" in the butterfly world. Whilst it is generally well-known that most caterpillars are "herbivorous" and generally feed on leaves, buds and flowers of plants, the Miletinae (or commonly referred to as the Harvesters) species' caterpillars feed on a variety of Homoptera like aphids, coccids, mealy bugs and one species even feeds on ants' larvae!

In Singapore, the Miletinae is represented by five genera - Allotinus, Logania, Spalgis, Miletus and Liphyra. Other than Liphyra, the other genera have caterpillars that feed mainly on a variety of Homoptera.

The aphids, coccids and mealy bugs, which form the principal diet of the caterpillars of the four genera mentioned, tend to feed on young shoots of various plants. These insects have adapted piercing mouth parts that pierce and suck the sap of plants - usually soft-stemmed ones. The Homoptera must suck large amounts of sap from the plant to get their nutrients. Much of the sap is a sugary fluid that cannot be digested. This extra liquid is passed through their body and excreted as "honeydew." Ants and other insects "farm" the Homoptera and collect honeydew for their own food. In return for their food, ants will protect the Homoptera that provide their colony with a food source.

In the field, observations have been made of the Miletinae adults feeding off the secretions of the aphids, mealy bugs and coccids. The butterflies do this brazenly, without any fear of being attacked, in the presence of the protective ants that are also 'milking' the aphids or mealy bugs of their honeydew.

Walking gingerly in a minefield of ants!

Besides feeding off the honeydew, the Miletinae also lay their eggs where the aphids and mealy bugs are present, and the caterpillars of these species feed on the aphids and mealy bug community.

A Pale Mottle (Logania marmorata damis) amidst mealy bugs and their "farmers"

It is interesting to note that the ants neither extract honeydew from, nor tend to the caterpillars in this case. They go about their business of tending to the aphids or mealy bugs, but leave the caterpillars alone - despite the caterpillars devouring their "herd"! Why then, don't the normally ferocious ants attack and kill the predatory caterpillars?

Miletinae caterpillars amongst their "sheep" which provides food as they grow

Researchers have postulated that the caterpillars (and even adult butterflies) have some kind of chemo-mimicry that render themselves 'invisible' to the ants. In other words, as far as the ants are concerned, the Miletinae adults and caterpillars are perceived as just another ant in the colony.

Hello? Are you my brother? An ant checks out a Lesser Darkie (Allotinus unicolor unicolor).

Therefore, although the caterpillars and adult butterflies of the Miletinae derive 'protection' from the ants, they give nothing back in return. On top of that, the adult butterflies partake of the honeydew that are secreted by the aphids and mealy bugs, and their caterpillars feed on the ants' source of food. Hence the "betrayal" part of the whole situation, where the ants have been hoodwinked into a win-lose relationship with the Miletinae.

A Lesser Darkie feeds on honeydew produced by some aphids that are tended by their farmer ants

An even more extreme situation occurs with the Moth Butterfly (Liphyra brassolis abbreviata). The caterpillar of this species feeds on the larvae of the Weaver Ant (Oecophylla smaragdina). It is interesting to note that the caterpillar feeds and grows inside the nest of the ants, and has evolved a clever way to escape the wrath of the ants when it ecloses. Our earlier blog article describes the Moth Butterfly.

A newly-eclosed Moth Butterfly (Liphyra brassolis abbreviata) whose caterpillar feeds on ant grub

This unique characteristic of the sub-family Miletinae in the butterfly world is amazing, and runs contrary to the conventional belief that all caterpillars are herbivorous and feed only on plant material. The adult butterflies of the five genera of the Miletinae found in Singapore are therefore very widespread, having little dependence on the location of host plants, as their "host" food is actually other living insects! Hence wherever there is a colony of aphids, coccids or mealy bugs, the adult butterflies of this sub-family will seek them out, for food for themselves as well as their young.

An Apefly (Spalgis epius epius) one of the Miletenae whose caterpillars also feed on Homoptera

So do look out for these butterflies and special behaviour when you are out in the field!

Text by Khew SK ; Photos by Sunny Chir, James Foong, Federick Ho, Khew SK, Loke PF, Bobby Mun, Horace Tan & Tan Tze Siong