27 December 2009

Butterfly Survival Strategies - Part 1

Butterfly Survival Strategies - Part 1

As most of us would know, butterflies are pretty, and virtually harmless insects. They have no primary defense weaponry, like bees, wasps, beetles and so on. They have no biting parts, nor possess any stings, claws, spikes, thorns or the like where they can hurt a would-be predator or attacker.

A Leopard Lacewing displays aposematic colours to warn predators that it is distasteful

How then, do butterflies survive the constant dangers and threats to their peaceful existence? As we have seen in this earlier blog article, butterflies' daily lives are fraught with danger, and indeed, a probably high proportion of adult butterflies form part of the daily diets of various predators and organisms in the animal world, like spiders, mantises, birds, wasps and so on.

A male Jacintha Eggfly (Hypolimnas bolina jacintha) dices with death in front of a bird

In this blog article, we take a look at the various strategies employed by adult butterflies to even the odds of surviving the web of life, and improving their chances of living their lives to the fullest extent of their life-span (which is, on average, 2-3 weeks for most species, some more, some less).

A skipper takes off in a flash if disturbed, using its speed as a primary defence to escape would-be predators

The first, and most fundamental defence mechanism that most butterflies have, would be speed. Coupled with their alertness, and enhanced sensitivity to movement, the majority of butterflies use 'fright' and 'flight' as their main means of escaping predators' attacks. As they have no 'fight', all that they can do, is to fly for their lives. Indeed, many a butterfly collector will have stories of the "ones that got away" - where butterflies that they have encountered, made that last-minute change in direction to frustrate collector and evade his net.

A group of Common Bluebottles (Graphium sarpedon luctatius) puddling together. Under normal circumstances, this butterfly is a fast and erratic flyer and is difficult for predators to capture it

Many species, like the Graphiums in the Papilionidae family, are exceedingly efficient at flying at extreme speeds and also with their erratic flight pattern, they would probably be a very difficult prey to pursue. Others like the Nymphalidae are skittish and very alert to movements within their Circle of Fear. The Pieridae often fly rapidly and restlessly, making them moving targets that are not easy to hunt down. And not forgetting the Skippers - the Speedsters of the Butterfly World with their rapid and darting flight.

A female Leopard Lacewing is vulnerable to predators as it stops to lay her eggs

However, the advantages of speed and alertness are somewhat diminished when the butterfly has to feed, mate, rest or oviposit. So how do they overcome the dangers of being eaten, when they are distracted by these necessary daily activities?

A Tree Nymph (Idea lynceus lynceus) displays aposematic contrast colouration

For some genera in various families, they are endowed with 'biological warfare'. In my recent article, on aposematism - the phenomenon of warning colouration in butterflies has been studied by none other than the famous Alfred Russell Wallace. Some species have been able to evolve by natural selection and evolution, to synthesise the chemicals in the plants that their caterpillars feed on and to present a distasteful and impalatable adult butterfly as a primary defense against predation. However, in the field, this phenomenon can work only with the sacrifice of a percentage of the individuals of the species - i.e. the predators have to first "learn" that the species is distasteful, or gives it a stomach ache if consumed. Then it knows well enough to avoid this species (or anything that looks like it) in future.

The high contrast aposematic colouration of black and yellow warns predators of its unpalatability

How then would the other species that are less fortunate in that they have no natural protection from predators? What strategies do they employ to ensure that they survive long enough to feed, find a mate, procreate so that the species avoids extinction?


The first strategy that butterflies employ is that of mimicry. The theory of mimicry was first explained by Henry Walter Bates in 1862, whereby he discussed the resemblance between insect prey that are defended by virtue of being "unpalatable" and those which lack such a defense. Batesian mimicry is therefore a form of deceptive mimicry because "palatable" prey deceive predators by their resemblance to undesirable species.

The classic case of mimicry as often quoted by Wallace - the female Common Mormon (Papilio polytes romulus) mimics the unpalatable Common Rose (Pachliopta aristolochia asteris) for protection. The black-bodied mimic sets it apart from the red-bodied model.

Wallace also explained the phenomenon of "sex-limited mimicry" where the mimetic resemblance could be limited to the female sex of the species. He continued to explain, with particular reference to the female of the Common Mormon (Papilio polytes) that "the female needs to survive for longer for oviposition.

Two examples of Batesian mimicry. Top : Female Courtesan (Euripus nyctelius euploeoides) [top left] mimics the Magpie Crow (Euploea radamanthus radamanthus), whilst the form-nivas of the Malayan Eggfly [bottom left] (Hypolimnas anomala anomala) mimics the Striped Black Crow (Euploea eyndhovii gardineri)

Mallet and Joron (1999) argue that, for example, females may need to engage in mimicry because selection of oviposition sites requires slow flight, and one way to be protected while flying slowly is to copy the colour patterns of typically slow-flying and chemically defended aposematic species.

A classic example of sex-limited Batesian mimicry where the female Wanderer (Pareronia valeria lutescens) mimics the unpalatable Danainae, the Yellow Glassy Tiger (Parantica aspasia aspasia) for protection. The female Wanderer even mimics the slow-flying characteristic of the Yellow Glassy Tiger

Batesian mimicry in which the mimic not only looks like the model, but also behaves like it, was easy to grasp and accepted by the scientific community during Wallace's era. It was easy to explain that this disguise increases the chances of the mimic being mistaken for the distasteful model which then gives it some “immunity” as it is avoided by its predators.

Example of Mullerian mimicry where a number of aposematic coloured, chemically-protected species mimic each other for even greater protection. In this case, the four species are, clockwise, Smaller Wood Nymph (Ideopsis gaura perakana), Common Tree Nymph (Idea stolli logani), Grey Tree Nymph (Idea lynceus lynceus) and a day-flying Zygaenid moth, Cyclosia pieridoides.

However, the explanation for mimicry between defended (or "unpalatable") species proved slightly more elusive until 1878, when Fritz Muller published an explanation for this form of mimicry. Muller elaborated that this form of mimicry originates from a strategy that has evolved among butterflies (and moths) is for all members of a group to resemble each other and also be unpalatable. This approach spreads the chances of any one butterfly (or moth) being eaten over a larger number of species, and over a larger number individuals within a species. When a bird catches any one of these individuals, it quickly learns to keep away from all the species within the group. This type of mimicry is now referred to as Mullerian mimicry.

To even the odds of survival, butterflies have, by natural selection and evolution, adapted to mimic other butterflies that are distasteful to predators, with the hope of protecting themselves from attack.

A Common Mime (Chilasa clytia clytia) [right] mimics the unpalatable Dark Glassy Tiger (Parantica agleoides agleoides)

In Part 2 of the Survival Strategies of Butterflies, we will see how butterflies employ crypsis - masquerate and camouflage to avoid being seen by predators as part of their way of keeping alive when going about their daily activities.

Text by Khew SK ; Photos by James Chia, Sunny Chir, Leslie Day, Khew SK and Tan BJ

24 December 2009

'Tis the Season to be Jolly!

ButterflyCircle Wishes One and All a Merry Christmas and a Happy 2010!

Christmas is upon us, and the weather here in Singapore seems to be dreary and all our favourite butterflies are probably taking a hiatus from their usual fluttering in this cold wet weather, and settled miserably under shelter.

But 'tis the season to be jolly (for us humans anyway), and to celebrate life and hope. Let's look forward to a new decade with optimism that more countries will do more to alleviate climate change & global warming.

Looking forward to 2010, which has been designated as the International Year of Biodiversity (IYB), we are certain that ButterflyCircle can contribute even more to enhancing butterfly biodiversity in Singapore as well as continue to learn more about butterflies. There are several projects that will be incorporating butterfly-friendly environments and trails coming onstream in Singapore - Gardens by the Bay, Sg Buloh Redevelopment Phase 2, Hort Park Butterfly Garden Phase 2 and so on to look forward to.

ButterflyCircle takes this opportunity to wish all our members and readers of the BC Blog a Merry Christmas and a Happy 2010!!! Three Cheers to our Beloved Flying Jewels!

Note on Photo : Featured is the 5th instar caterpillar (that has just moulted from its old skin) of the Archduke (Lexias pardalis dirteana), one of my favourite 'cats'. I've always likened it to a Chrismas tree, and the intricate spines and hairs make it appear like a complex snowflake too.

19 December 2009

Life History of the Plain Plushblue

Life History of the Plain Plushblue (Flos apidanus saturatus)

Butterfly Biodata:
Genus: Flos Doherty, 1889
Species: apidanus Cramer, 1777
Subspecies: saturatus Snellen, 1890
Wingspan of Adult Butterfly: 34mm
Caterpillar Host Plants:
Terminalia catappa (Combretaceae, Common name: Sea Almond), Syzygium glaucum (Myrtaceae), S. grande (Myrtaceae) and other Syzygium species (yet to be identified).

A Plain Plushblue perching on a leaf in the nature reserve.

Physical Description of Adult Butterfly:
Above, the male is deep bluish violet, with a narrow forewing border (about 1.0mm); the female is bluer and more shining, with rather regular black borders on the costal and distal margins of both wings. Below, the wings are pale yellowish to darker brown with whitish markings featuring a purple tinge. The discal and post-discal bands are evenly curved on the forewings, and there is a pale yellowish end-cell bar on the forewing. Hindwings have irregular discal whitish bands from mid-costa to mid-dorsum. There is a small ochrous brown patch at the base of the costa on both wings. The hindwing is tailed at vein 2 and toothed at veins 1b and 3. The compound eyes are dark yellow brown (see the cover picture of this earlier blog article).

A close-up view of the front portion of a Plain Plushblue.
Note that the ochrous brown patches at behind the head.
Field Observations of Butterfly Behaviour:
Worldwide, Flos apidanus is the most widely distributed member of the Flos genus. This is also true locally in Singapore as it can be found in multiple locations, in and out of the nature reserves, and it is the most commonly sighted of the four Flos species residing here. The fast flying adults are usually spotted near flowering shrubs and their host plants. Typically they perch with their wings closed, but they can also be seen to open their wings fully to sunbathe in warm weather.

A female Plain Plushblue perching on a leaf in the Southern Ridges.

Early Stages:

It is mentioned in C&P4 that the Plain Plushblue utilizes a number of Syzygium species as larval hosts. So far we have established that Syzygium glaucum and S. grande serve this role in Singapore. In addition, Terminalia catappa (Sea Almond) has been recorded as another host. This latter plant can grow to be a rather large tree with a pagoda shape. Its leaves are obovate, 20-30cm long, often spirally crowded at ends of branches, and turning orange or red before they fall. The 4-5cm long fruits are flattened ovoid and keeled all round. The seeds are edible. Sea Almond is common in Singapore, either growing wild or cultivated as roadside trees.

Host plant: Sea Almond. Leaves and fruits are featured here.

Host plant: a Syzygium species yet to be fully identified.

A female Plain Plushblue laying eggs at the petiole of a Syzygium species.
Eggs are laid in small groups of 2-5 on the petiole or the underside of a relatively young leaf of the host plant. Each egg is about 0.9mm in diameter, white with a light yellowish green tinge. It is shaped like a pressed bun with a slightly depressed micropylar area atop. The surface has a coarsely reticulated pattern of intersecting ridges.
Groups of eggs of the Plain Plushblue on young shoots of the Sea Almond.

Closer looks at groups of eggs of the Plain Plushblue.

It takes 2-3 days for the egg to hatch. The newly hatched is pale yellowish in body color and has a length of about 1.5mm. It has a rather flattened woodlouse appearance with a large semicircular prothorax, a yellowish brown head and
long dorso-lateral and lateral setae. There are also a fair number of very short setae on the body surface.
Two views of a newly hatched caterpillar, length: 1.5mm.

The 1st instar caterpillar feeds by skimming the surface of a young leaf, but later instars are able to consume the lamina in whole.
Larval stages of the Plain Plushblue are gregarious and a few caterpillars have been observed in the field sharing a feeding site with no animosity towards each other. As the 1st instar caterpillar grows, its body color becomes more yellowish green. Pinky red patches also appear on the front portion of the prothorax and the posterior abdominal segments. After 2-3 days of growth, and reaching a length of about 2.5mm, the caterpillar moults to the next instar.
Two views of a 1st instar caterpillar, length: 2mm.

The 2nd instar caterpillar features long lateral hairs and a black head. Long dorso-lateral setae are no longer present, but many short setae with blobbed endings appear on the entire body surface. A pair of faint dorso-lateral line runs along the length of the body. The prothorax is marked by a large black patch with a leading edge in pinky red. The dorsal nectary organ (DNO) is already visible on the 7th abdominal segment and highlighted with a small dark reddish patch stretching to the 8th segment. A large anal plate, black in color, dominates the remaining posterior segments.

Two views of a 2nd instar caterpillar, early in this stage, length: 2.5mm.

2nd instar caterpillar, late in this stage, length: 3.5mm.
The 2nd instar caterpillar has a functional DNO as ants living in its proximity are observed to actively attend to the young caterpillars, having been attracted to the nectary fluid excreted via the DNO. The ant-caterpillar association continues for all remaining larval stages of the Plain Plushblue.
A 2nd instar caterpillar being tailed by an ant which is eyeing the nectary fluid excreted by the caterpillar.

A sequence of three pictures showing an ant receiving its pay packet of a nectary droplet from the 2nd instar caterpillar.

The 2nd instar caterpillar reaches a length of about 4mm, and after about 3 days in this stage, it moults again. The 3rd instar caterpillar resembles the 2nd instar caterpillar closely. New to this instar is a dorsal band in darker green against the yellowish green base colour. The DNO is now rather prominent with an dark brown oval ring marking its outer boundary. The 3rd instar takes about 3-4 days to complete with the body length reaching about 7mm.
Two views of a 3rd instar caterpillar, length: 5.5mm.

A small group of two 3rd instar caterpillars attended by ants.

The 4th instar caterpillar has similar markings as the 3rd instar. One notable change is in the prothoracic dark patch which now has two small white patches embedded at its posterior. Another change is in the dark red patch stretching from the DNO to the anal plate as it now has two side-branches reaching the tentacular organs (TOs) on the 8th abdominal segment. The 4th instar takes about 4-6 days to complete with the body length reaching 11mm.

4th instar caterpillar, length: 11mm.

Two views of a 4th instar caterpillar being attended to by three ants.
The 5th instar caterpillar has similar but more striking markings. Visible changes are 1) a white intermittent line running down the middle of the dark patch on the prothorax; 2) both the dark patch on the prothorax and the anal plate are now flanked by white borders which are moderate in thickness.

5th intar caterpillars, legnths: 15.5mm (top) and 19mm (bottom).

A group of three 5th intar caterpillars sharing one leaf.

The DNO and the TOs at the posterior segments of a 5th intar caterpillar.
The right picture shows the wet DNO after a recent excretion.

Dorsal views showing the newly excreted droplet atop the DNO.
Lateral views of the same nectary droplets at the DNO.

After 7-8 days of feeding and reaching a length of about 20mm, the caterpillar slows down and stops food intake for about 1 day. During this time, its body length gradually shortened. Soon it becomes an immobile pre-pupa in its leaf shelter.

Two views of a pre-pupa of the Plain Plushblue.

The pre-pupa caterpillar prepares for pupation by spinning a silk girdle and a silk pad to which it attaches via claspers at its posterior segments. After 1 day as a pre-pupa, pupation takes place. The pupa, with a length of 12-14mm, has a shape typical of any Lycaenid species, but with a somewhat produced anal segment. It is yellowish green in coloration.
A time-lapse sequence of the pupation event for a Plain Plusblue caterpillar.

Two views of a pupa of the Plain Plushblue, length:12mm.

Nine days later, the pupa matures enough to show the markings on the forewing upperside. The next day, the pupal stage comes to an end with the emergence of the adult butterfly.

Mature pupae: female (top) and male (bottom).

A newly eclosed Plain Plushblue resting on a leaf.

Unlike most of the Lycaenidae species, the caterpillars of the Plain Plushblue have the habit of constructing leaf shelters in which they rest and seek safety between feeds on the lamina of nearby leaves and part of the shelter. Pupation also takes place within a leaf shelter.

Leaf shelters used by Plain Plushblue caterpllars on Syzygium gauclum.

A leaf shelter formed by joining two adjacent leaves.
Can you spot the caterpillar?

  • 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 Federick Ho, Khew SK and Horace Tan.