16 September 2017

Butterfly of the Month - September 2017

Butterfly of the Month - September 2017
The Forest Grass Yellow (Eurema simulatrix tecmessa)

A Forest Grass Yellow feeding on the flower of the Mile-A-Minute weed

September is upon us already and we are well into the 9th month of 2017. Looking back at the Butterfly of the Month articles from the past few years, one thing evident is that the choking haze from the burning of agricultural land in Indonesia has not hit us for the past 24 months. It looks like the Indonesian government has made good its promise to eliminate this annual polluting scourge that has affected neighbouring Malaysia and Singapore. let's hope that the unsustainable practice of forest-clearing by slash and burn will see the end in the coming years ahead.

On the international scene, an area of concern is North Korea's show of power in the launching of several intercontinental ballistic missiles and also the testing of a Hydrogen bomb. The explosion, which had a purported yield of 250 kilotons would be about 16 times the size of the bomb that the US dropped on Hiroshima in World War II. Such powerful weapons in the hands of the wrong people would have dire consequences for the entire world.

Back home in Singapore, we have the first female President since independence and what would have been an unprecedented event and a special occasion was marred by the fact that the 'elections' had only one eligible candidate. This caused a uproar in the local community and social media was, as usual, debating the whole issue of how the situation came to a rather undemocratic conclusion to the Presidential Elections. Irrespective of which side of the argument you are on, Madam Halimah Yacob will be the 8th President of the Republic of Singapore.

A Forest Grass Yellow feeding on the purple Snakeweed flower

The Hungry Ghost Festival is a Buddhist and Taoist festival set on the 15th day of the seventh lunar month, also known as the Ghost Month or 七月 (qi yue). However, 2017 is special in that the year contains a leap month whereby an additional month is added to the calendar, pushing the official Hungry Ghost Festival into the month of September this year, instead of falling in the month of August. Nevertheless, some of the superstitious beliefs during the Hungry Ghost month are to avoid wearing red (because ghosts are apparently attracted to red) and not moving house or getting married!

We now come to our Butterfly of the Month for September 2017 - the Forest Grass Yellow (Eurema simulatrix tecmessa). This is one of six species of the Eurema spp. that are found in Singapore, and is only considered moderately common. It is one of the forest-dependent species that is not often found in urban parks and gardens, unlike its other more urbanite cousins like the Common Grass Yellow or Three Spot Grass Yellow.

The Forest Grass Yellow is one species that has two cell spots on the underside of the forewing cell area. The large, almost cleft reddish-brown apical patch quite easily distinguishes this species from the other related species of Grass Yellows. In addition, on the underside of the hindwing is a sub-costal brownish bar that is quite distinct and also a basal spot in space 7.

The upperside is a lemon yellow with black marginal borders on both the fore and hindwings. Reference literature also indicate that the inner edge of the black border in spaces 1a and 1b slope towards the base of the wings.

One, Two, Three Forest Grass Yellows puddling on damp sandy streambanks

Males of the Forest Grass Yellow are often encountered puddling on damp sandy stream banks in the nature reserves. The females do not puddle but are observed feeding at flowering plants. Females of this species tend to attain rather larger wingspans than the other species in the genus, sometimes reaching up to 50mm from wingtip to wingtip.

A trio of Forest Grass Yellows puddling together

Despite being a relatively common species in the forested areas of Singapore, the Forest Grass Yellow's life history has not been recorded yet. If there are any observers out there who have seen the females of this species ovipositing on its host plant do let us know or better still, if you are able to take a photograph of the host plant, send it to us.

Text by Khew SK : Photos by Federick Ho, Khew SK, Koh CH, Loke PF, Jonathan Soong, Tan BJ, Tea Yi Kai and Anthony Wong

09 September 2017

Upside Down Butterflies Part 2

Upside Down Butterflies Part 2
Peculiar habits of some Butterfly Species

A Common Awl perches upside down on the underside of a palm

In last week's blog article, we featured an interesting and peculiar habit of some species of butterflies. These butterflies have a propensity of perching under a leaf to hide, sometimes with their wings folded upright, others with their wings opened or flapping slowly. Not all butterflies do this, but only a handful and isolated to a few of the butterfly families found in Singapore.

A White Banded Awl on the underside of a leaf

Their reasons for doing so may be common sense - either taking shelter from the heat of the sun, or pelting rain, or even to hide themselves from would-be predators. Even if this is so, then why only these few species? Why don't all butterflies adopt this behaviour? I doubt if these questions can be definitively answered. This is probably one of a myriad of Mother Nature's mysteries. The upside down behaviour is likely to be an evolutionary process of some of these species, carried in their DNA for generations. Each successive generation adopts the identical habits and seems to know what to do without being 'taught' how to do so.

The Riodinidae found in Singapore do not display the under-leaf habit, despite many species in other parts of the world doing so.

We now take a look at the next family of butterflies, continuing from last week's article - the Riodinidae. This family, known as the "Metalmarks", is represented by only 5 species in Singapore. Across the globe, in South America, many of the magnificent metalmarks are well-known to always perch under a leaf, either with their wings opened flat, or folded upright. However, all the 5 Riodinidae species in Singapore are not known to display any under-leaf habits at all. Most of them are usually seen on the top surfaces of leaves, and has a habit of twisting and turning with half-opened wings.

The Sumatran Sunbeam perches upside down quite regularly when observed in the backmangroves of Singapore

Turning our attention next to the Lycaenidae, which is the largest family of butterflies found in Singapore, we observe that of the 2 members of the sub-family Curetinae, one of them - the Sumatran Sunbeam is known to perch on the undersides of leaves with their wings folded upright. Often, their bright white undersides make them very visible when they hang upside down under a leaf. However, the other related species, the Malayan Sunbeam, rarely displays such behaviour.

The Poritinae do not perch under leaves whilst the Miletinae adopt any position just to feed on the excretions of other insects

The other subfamilies, Miletinae and Poritinae, do not display any upside down habits, preferring to stay on the tops of leaves, or in the case of the Miletinae, they adopt whatever convenient posture needed when feeding on the secretions of mealy bugs or aphids. I have not come across any Polyommatinae (the Blues) that perch on the undersides of leaves either.

Both the Silverlines in Singapore display the under-leaf behaviour occasionally

The family Aphnaeinae is represented by two species - the Club and Long Banded Silverlines in Singapore. I have occasionally seen the Silverlines perched on the underside of a leaf. However, this is not a regular behaviour, although we can count the Silverlines as being one of them displaying this under-leaf habit.

Some of the long-tailed Lycaenidae butterflies sometimes hide upside down under a leaf

In the last sub-family, Theclinae, there are one or two species, particularly amongst the long-tailed ones, that occasionally display the habit of perching under a leaf. However, again, this habit is not predominant but only occurs uncommonly from time to time. There have been times when I encounter an individual under a leaf, but they appear to be foraging for something or feeding. Some of the Rapala spp are known to do so. But infrequent are the occasions when I encounter one that is just perched on the underside of a leaf, doing absolutely nothing.  However, in Malaysia, there are certain species of the genus Dacalana and Neomyrina that are typically found perched in the upside down position. These species are not found in Singapore. 

We now move on to the final family, the Hesperiidae or Skippers. Amongst two of the sub-families Coeliadinae and Pyrginae are many species that consistently displays the under-leaf habit. The sub-family Hesperiinae has no known examples of perching under a leaf. We will now feature the species from the Coeliadinae and Pyrginae that regularly perches in an upside down position.

A Brown Awl perches upside down under a leaf

The first group will be the Awls. These species, belonging to the four genera Badamia, Burara, Bibasis and Hasora, are known to be crepuscular (active during the periods of dawn and dusk) in habit. When encountered, they can often be seen to perch upside down on the undersides of foliage usually in the early morning hours before 8 or 9 am, or during the later hours of the day in the deep forest understorey.

Awlets and Awls all upside down

Amongst these, the Brown Awl, Great Orange Awlet, Orange Awlet, Plain Banded Awl, Common Awl, Yellow Banded Awl, Common Banded Awl and White Banded Awl can regularly be observed to perch on the underside of a leaf in forested areas. A few of them can be active during the later hours of the day, like the Yellow Banded Awl and White Banded Awl, but usually in deep forest and hiding in the shade under a leaf.

These robust-bodied skippers are fast-flying and zip rapidly from perch to perch, sometimes even buzzing close to an observer, before settling on the underside of a leaf to hide. I have not come across the sole member of the sub-family, the Orange Tailed Awl, hiding under a leaf, but it is very likely that it also displays this habit.

The final sub-family is the Pyrginae (commonly referred to as the "Flats"). The species of this sub-family tend to open their wings flat (hence the collective name). However, during certain hours of the day, after they are done feeding on flowers, they will fly rapidly and hide upside down under a leaf - still with their wings opened flat. When behaving like this, it is challenging to photograph them, especially when they are perched on a low leaf.

The Flats are also habitual under-leafers, preferring to perch upside down with their wings spread open

Amongst the Flats that have been frequently seen perched under a leaf with their wings opened flat are White Banded Flat, Fulvous Pied Flat, Hieroglyphic Flat, Common Snow Flat, Large Snow Flat, Ultra Snow Flat, Malayan Snow Flat and Chestnut Angle. Whilst there may not be photos of the other species found in Singapore to show that they perch under a leaf, it is most likely that they do. A quite a few of these Pyrginae are very rare. However, their under-leaf behaviour is limited to certain hours of the day when they are not feeding or sunbathing.

A White Banded Flat clings on to the underside of a leaf in its typical upside down perch

And so we complete our observations on this peculiar habit of perching upside down on the underside of a leaf by some butterfly species. Perhaps some researcher will one day discover the purpose of this unique habit that only certain species of butterflies display. Until then, we can just observe and wonder about this under-leaf behaviour amongst these butterflies.

Text by Khew SK : Photos by Khew SK, Koh CH, Loh MY, Loke PF, Billy Oh, Nelson Ong, Jonathan Soong and Horace Tan

Upside Down Butterflies - Part 1

02 September 2017

Upside Down Butterflies

Upside Down Butterflies
Peculiar habits of some Butterfly Species

A Common Yeoman perches upside down with its wings folded upright

Most regular butterfly watchers will know that the flying speed and style of flying vary amongst the species of butterflies found in Singapore (and elsewhere for that matter). After a time of watching them, a butterfly watcher should be able to tell the difference between the fast-flying Papilionidae like a Tailed Jay or a Banded Swallowtail, always flying as though the devil were at their heels; and the slow, unhurried graceful flight of a Common Tree Nymph.

A Little Maplet peeks from its upside down perch

Besides having their preferred habitats, many butterfly species have unique behavioral adaptations that are interesting and help to narrow down the identification of several species, simply from the way they behave in the field. One such interesting behaviour amongst butterflies, is the peculiar habit of flying and then settling on the underside of a leaf, hanging upside down like a bat.

Anderson's Grass Yellow perches upside down on a grass blade

It is not fully understood why some butterflies do this. Perhaps to hide from a predator? Or is it for some other reason? Not much research has been made to establish why some butterflies rest upside down on the underside of its leaf perch. In most cases, the butterfly just rests on the underside of a leaf and stays there, doing absolutely nothing. There is usually no food source nor is the butterfly engaging in any specific activity. There are some species that oviposit on the underside of a leaf, but here, we are discussing those species that do nothing else except perch on the underside of a leaf.

A male Purple Duke perches upside down.  This species is most often encountered in the nature reserves displaying this under-leaf habit

The "king" of the upside down butterflies should be the Purple Duke (Eulaceura osteria kumana) also known as the Elegant Emperor in some countries. This species is regularly seen displaying the under-leaf habit. When disturbed by any movement, the Purple Duke darts out, flies rapidly and then suddenly stops on the underside of a leaf to perch with its wings folded upright. It will repeat this behaviour again and again.

Purple Duke males (Top and Middle) and female (Bottom) showing their usual upside down perching behaviour

This unique upside down behaviour occurs in both males and females of the Purple Duke. Occasionally, it perches on the top of a leaf and opens its wings flat to sunbathe. But getting a good shot of an open winged Purple Duke is quite challenging, as it usually sunbathes in the early hours of the morning before the sun warms up the environment.

The Papilionidae usually perch on the tops of leaves when they need to rest after flying, like this female Great Helen is doing.  Sightings of them perching under a leaf are extremely rare, if ever!

Going through the families of butterflies, we start at the Papilionidae. I have not come across any species of the Swallowtails and Birdwings in Singapore that displays the perching under-leaf behaviour. Perhaps due to their large size, it would be physically difficult for a Papilionidae to hold on comfortably to the underside of a leaf. The Crows and Tigers of the subfamily Danainae also do not display this behaviour at all.

Different species of the Eurema are often encountered perching in an upside down position on the underside of a leaf

Surprisingly, there are some species of the Pieridae, particularly the Eurema spp. or Grass Yellows, displaying this habit. Although it is not a frequent habit amongst these species, they have quite often been seen to rest on the underside of a leaf with their wings folded upright. This is more often observed when there is a whole group of puddling Grass Yellow butterflies and some will fly off to nearby bushes to rest upside down after feeding.

A Common Grass Yellow clings upside down on the underside of a leaf

However, they are skittish and alert and will fly off elsewhere if disturbed. Unlike the Purple Duke, they may not fly to another upside down perch. Amongst the other Pieridae, I have observed some species of the Catopsilia often referred to as the Emigrants, hiding on the underside of a leaf. However, such sightings are not common.

Although not often seen displaying the under-leaf behaviour, the Jacintha Eggfly (Top) and the Autumn Leaf (Bottom) are sometimes seen hiding upside down on the underside of a leaf

Moving on to the family Nymphalidae, I have not had the chance of observing any of this upside down behaviour amongst the subfamilies Danainae, Satyrinae, Charaxinae Biblidinae and Limenitidinae. Amongst some species of the Nymphalinae, I have come across this under-leaf behaviour in the Autumn Leaf, Malayan Eggfly, Great Eggfly and Jacintha Eggfly. However, the occurrence of such upside down habit is rare and in some cases, the butterfly that I observed was ovipositing or feeding on some sap on the underside of the leaf.

The Cirrochroa species found in Singapore - Malay Yeoman, Banded Yeoman and Common Yeoman are seen to display this upside down perching behaviour at times.  In this photo, a Banded Yeoman clings onto the underside of a leaf with its wings folded upright.

The subfamily that features several species that has the habit of resting on the underside of a leaf is Heliconiinae. In Singapore, all three species of the Cirrochroa spp. usually referred to as the Yeoman butterflies, are often observed to hide on the underside of a leaf with their wings folded upright to rest. Although this behaviour does not happen quite as often as in the Purple Duke, there are more frequent sightings of the Yeoman butterflies displaying this upside down habit. In some observations, the butterfly clung on to the underside of a leaf, but kept opening and closing its wings for a period of time.

The Royal Assyrian is another species that is often encountered perched upside down on the underside of a leaf with its wings folded upright.

Another species in the Heliconiinae family that can be said to often display this under-leaf habit, is the Royal Assyrian (Terinos terpander robertsia). This species is the only representative of the genus in Singapore, but again, it has often been photographed whilst perched on the underside of a leaf with its wings folded upright. In some encounters, the butterfly was in full view although perched on the underside of a leaf, giving reason to wonder if it was doing so to avoid being seen, or for some other reason yet to be discovered.

The Little Maplet has a habit of perching upside down on the underside of a leaf with its wings opened flat.  It flaps its wings slowly and is alert to any intrusion to its hiding place

In the last subfamily of the Nymphalidae, is the sole representative of Cyrestinae in Singapore - the Little Maplet (Chersonesia peraka peraka). This small butterfly is very skittish and has the habit of stopping on the underside of a leaf with its wings opened flat. It then flaps its wings slowly open and close whilst perched in the upside down position. When disturbed, it repeats this behaviour and moves from leaf to leaf, often testing the photographer's patience to the limit!

So, if anyone out there has done specific research on why some butterfly species displays this behaviour of perching upside down like a bat, on the underside of a leaf, please share your views in the comments section below. Or if anyone has other photos of other species displaying this under-leaf behaviour, kindly also share your observations.  The next part of this article will feature species from the Lycaenidae and Hesperiidae species that also display this upside down habit.

Text by Khew SK : Photos by Chng CK, Federick Ho, Khew SK, Jonathan Soong, Horace Tan and Anthony Wong