Butterfly Anatomy : Part 2

Butterfly Anatomy : Part 2
Wing Venation on a Butterfly's Wings

The prominently darkened veins on the hindwing of the Common Birdwing illustrates the wing venation and all the veins that originate from the cell

In the next article of our series on butterfly anatomy and scientific terminology, we take a closer look at the wings of the butterfly. The wings constitute one of the important parts of a butterfly in classification and identification work. The ability to understand the terms that are used to reference various parts of a butterfly's wings is critical to butterfly identification. This article focuses on the veins on the butterfly's wings and how they are named.

This backlit shot of a Lemon Emigrant shows the vein structure and arrangement clearly

The wings of a butterfly are membranous with veins running longitudinally from the base (where the wings are attached to the thorax) to the outer margins of the wings. The pattern and arrangement of these veins (wing venation) is an important diagnostic tool in the identification of butterflies. It is therefore important to understand the wing venation as a reference to locating features that are associated with the veins/spaces on a butterfly's wings. In some cases, the arrangements of the veins themselves will give important clues to the genus of the butterflies.

The raised veins are prominent in this Malay Lacewing and show clearly how the veins are arranged

The veins of a butterfly's wings gives the structural strength to the soft membranous wings onto which the scales are attached. These veins are tubular, in which a liquid 'blood', or haemolymph circulates within them.

The Comstock system of butterfly wing vein notation.  Whilst the system has a strong scientific basis, the numbering system requires a bit of understanding and is not easy for a hobbyist enthusiast to understand.  It is probably for this reason that, for butterflies, it is easier to understand the more intuitive Numerical Notation system.

A butterfly's wing venation has been used extensively in the classification and identification of butterflies and the nomenclature of the veins in insects usually follows the system adopted by JH Comstock (referred to as the Comstock, 1918 system). However, a simplified and more intuitive Numerical Notation system pioneered by Herrich-Schaffer is more commonly used. Basically, this system numbers the veins from 1, which represents the anal veins (1a and 1b) through to number 12 on the forewing, and 1a and 1b to 8 on the hindwing. Note however, that not all butterflies have the full set of veins on both wings, and may vary from species to species.

A typical wing venation of a butterfly based on the Numerical Notation system. Note the naming of the spaces between the veins 

In the Numerical Notation system, veins 2 to 11 on the forewing and 2 to 7 on the hindwing originate from the cell. The remaining veins originate from the wing bases. The interspace between two veins is known by the number of the lower vein. E.g. the space between veins 2 and 3 is referred to as "space 2".


In the identification of a Dingy Line Blue, the reference to the ocellus in space 2 being a diagnostic feature is clearer when one is able to find "space 2" on the hindwing by understanding the numerical naming of the wing venation and spaces between the veins.

This is an important convention to understand, as for example, the description of "the ocellus in space 2 of the hindwing is moved inwards" immediately directs the observer to that particular part of the wing to observe this diagnostic feature that distinguishes the Dingy Bush Brown (Mycalesis perseus cepheus) from its other lookalike cousins.

In the examples below, we illustrate how wing venation is used to refer to certain features of a butterfly. We will compare a few photographs of actual butterflies with the numerical system of naming the veins and how these wing veins appear in the actual individuals.

The Common Rose (Pachliopta aristolochiae asteris) - Species of the family Papilionidae tend to have the full complement of veins from 1a to 12 on the forewing and 1a to 8 on the hindwing (with vein 1b missing).


Diagrammatic representation of the wing venation of the Common Rose

For example, when a description of the Common Rose states "there is a spatulate (spoon-shaped) tail at vein 4 of the hindwing", it is now easy to look at the veins and understand where the location of the tail at vein 4 is.

The Striped Blue Crow (Euploea mulciber mulciber) - The Danainae feature species that have almost the complete complement of wing veins on both wings, with the exception of vein 1a on the forewing. In the case of this male Striped Blue Crow, the veins are clearly seen on the brownish base colour of the wings.


Diagrammatic representation of the wing venation of the Striped Blue Crow

Take a close look at the hindwing veins on the butterfly. Can you trace all the veins from vein 2 to vein 7 to the cell on the wing? On the hindwing in all butterflies, veins 2 to 7 always originate from the cell.

The darkened veins of the Painted Jezebel are helpful in locating and understanding the position of the veins on the wings.

The Painted Jezebel (Delias hyparete metarete) - Many species of the Pieridae feature the full complement of veins from 1a to 8 on the hindwing. However, several veins are missing from the forewing, where veins 1a, 8 and 10 are not present.


Diagrammatic representation of the wing venation of the Painted Jezebel

The Painted Jezebel, like several species in the Pieridae family, is also interesting in that the veins on the wings are darkened and it is quite easy to trace most of the veins in the butterfly when looking at its wings.

The Common Posy (Drupadia ravindra moorei) - A example of a Lycaenidae and the wing veins in this species. Many species in the Lycaenidae family have veins 8 and 9 are missing from the forewing.


Diagrammatic representation of the wing venation of the Common Posy

Looking at the hindwing veins, a description such as "the hindwing has three white tails at veins 1b, 2 and 3, of which the longest is the one at vein 2" becomes easier to understand.

In the next article, we will discuss the names of the different parts and zones on the wings of a butterfly and how we can use these references together with the wing venation and external margin names of the wings to find the diagnostic features in the identification of butterflies.

Text by Khew SK : Photos by Sunny Chir and Khew SK : Wing venation diagrams taken from Butterflies of the Malay Peninsula by Corbet and Pendlebury, 4th edition

Butterfly Anatomy

Butterfly Anatomy : Part 1
Scientific Names For Different Parts of a Butterfly


Names for the different parts of the forewing of a butterfly

In the appreciation of butterflies, nature's winged jewels, it is also important to be able to appropriately refer to the correct names to the different physical parts of the butterfly. Just like any bird, animal or even an inanimate object, like a car, there are proper names given to each part so that anyone describing or referring to the different aspects or parts of it can be universally understood.

Names for the different parts of the hindwing of a butterfly

This is no different for a butterfly, which has proper terms to describe different parts of its wings or body. In this blog article, we will systematically learn about the different parts of a butterfly from basic terminology to the detailed biological terms used by scientists to describe a butterfly's physical attributes. This article is not meant to be comprehensive or exhaustive, as a complete glossary of the scientific terminology may be too daunting for a hobbyist trying to learn about the proper names given to the different parts of a butterfly.

In many references, both online and in hardcopy books, diagrams and graphics depicting the different parts of a butterfly are often too complicated. This may be due to packing in as much information as possible for efficiency, where a lot of information is crammed into a single picture. I will attempt to introduce the anatomical features of a butterfly and their respective proper names progressively from the commonly used terms to more detailed scientific terminology.

Firstly, when one takes a look at a butterfly, the basic information would be the body and wings of the insect. Fundamentally, the body is divided into three segments - the head, thorax and abdomen. Then we take a look at the wings. All butterflies have four wings - left forewing, right forewing, left hindwing and right hindwing.

At the next level, would be the different parts found on the head, thorax and abdomen. These are important parts of the butterfly and often described or elaborated in references as part of the diagnostic features in butterfly identification. For example, the colour of the shaft of the antenna just after the club is a diagnostic feature for some skippers, whilst the shape of the tip of the abdomen can help to separate between a male and female of a species of butterfly.

Hence on the head, the important parts that should be highlighted are the antennae, eyes, palpi and proboscis. The middle section of the body, the thorax, is best thought of as a muscular anchor to which the head, legs, segmented abdomen, and wings are attached. The abdomen contains the digestive system, breathing apparatus, a long tubular heart, and the sexual organs. The abdominal exoskeleton is multi-segmented. Each of the 10 segments is comprised of a ring of a hard material called chitin. The segments are linked by flexible tissues, allowing the abdomen to bend, a necessity for copulation and egg-laying.

Upperside and underside of the wings of the same butterfly

Moving to the next level of detail, would be the wings and the correct names for different parts of the wings. Firstly, when we refer to the upperside (or dorsal) and underside (or ventral) side of the wings, the photos above indicate the convention for this. And then, considering that a butterfly's wing is triangular-shaped, each margin and angle has a given name.


Names for the external margins of the forewing and hindwing of a butterfly

Hence a butterfly enthusiast should familiarise himself with the names of these parts of a butterfly's wings. This is because when taxonomists describe the features of a butterfly's wings e.g. "the forewing apex is rounded in the female...", one will know exactly where to look at, and which part of the wing the description is referring to.



The terms apex, termen, base, tornus, dorsum and costa should be the next taxonomic terms that an enthusiast should know and remember. These are the general terms applied to the external edges of a butterfly's wings and are quite key to describing the wings.



When the description refers to the forewing dorsum margin (straight or curved) of the Dwarf Crow, an observer will be able to focus straightaway on the correct part to see the differences described.

In subsequent parts of this Butterfly Anatomy series, we will go into the wing surfaces, veins and internal taxonomic names for different parts of a butterfly's wings, and other detailed names of other different parts of a butterfly that is often used as descriptors and diagnostic features to identify different species. A glossary of other commonly used taxonomic terms will also be discussed.

Text by Khew SK ; Photos by Bob Cheong, Khew SK and Loh MY

Lancers of Singapore

Lancers of Singapore
Featuring the Lancer skippers


The rare Yellow Chequered Lancer (Plastingia pellonia) perches on a leaf

This weekend's blogpost focuses on a group of butterflies in the Hesperiidae family (Skippers) that are collectively given the common English name of "Lancer". As shared in earlier posts on this blog regarding the interesting backgrounds in which the early collectors coined common names for butterflies, we have to sometimes do a bit of "forensic" analysis of some of these names to try to understand how some of these names originated.

The Yellow Vein Lancer (Pyroneura latoia latoia) is often observed at the flowers of the Bandicoot Berry (Leea indica) in the forested nature reserves of Singapore

Doing an online search for the meaning of "Lancer" would turn up primary definitions like "A soldier of a cavalry regiment armed with lances" or "a soldier who belongs to the part of an army that used lances in the past." The keyword in this case focuses on the word "lance" which is usually a long-handled weapon that is in the form of a spear. So the obvious etymology of the word "lancer" centres on a military personnel brandishing a long weapon.


A Chequered Lancer (Plastingia naga) perches in the shaded understory of its favourite habitat

So why would a butterfly have anything to do with a "Lancer"? This is the part that is probably more difficult to establish, and we can only speculate without any guarantees of a definitive conclusion, as there are often multiple viewpoints from which an observer can come to his own inference regarding a name.



Skippers, the collective name given to butterflies of the Hesperiidae family, are usually stout-bodied, moth-like in appearance and fast flyers. The individual species that are referred to as "Lancers" vary across different genera. But like most species of the family, they are skittish and zip around with great speed. Perhaps the early collectors saw in these species, a military-like demeanour in their wing shape and flight reminding them of soldiers brandishing lethal-looking weapons? A bit challenging to try to imagine these beautiful gentle creatures in that light, but to each his own.

The Chequered Lancer (Plastingia naga)



The first species that we feature here is the Chequered Lancer (Plastingia naga). That the Chequered Lancer is referred to by only its species name suggests that the butterfly is consistent throughout its geographical range with almost no perceptible differences in its appearance across the different countries where it occurs.



The underside of the Chequered Lancer has an attractive pattern of black veins and white rectangular spots. The upperside is a medium brown with hyaline spots on the forewings and yellowish streaks on both wings. The abdomen is striped black-and-white whilst the antennaa has a whitish band just after the club.


A Chequered Lancer sunbathes in the late afternoon showing its uppersides

A Chequered Lancer perches on the upperside of a leaf of its caterpillar host plant, Fishtail Palm (Caryota mitis)

The Chequered Lancer prefers well-shaded forest habitats where it perches on the top surfaces of leaves. It flies off rapidly when disturbed but often not too far away from its preferred habitats. The caterpillar of this species has been successfully bred on the Fishtail Palm (Caryota mitis) in Singapore.

The Yellow Chequered Lancer (Plastingia pellonia)



The Yellow Chequered Lancer is closely related to the Chequered Lancer and belongs to the same genus. It can be found in the same heavily-shaded habitats as the Chequered Lancer, but is much rarer, and usually spotted deep in forested areas within the nature reserves of Singapore.


A Yellow Chequered Lancer extends its palpi making it appear strange

The Yellow Chequered Lancer has a similar pattern on the underside of its wings to the Chequered Lancer, but instead of white spots, the overall ground colour of the butterfly is black-and-yellow, instead of black-and-white. The wings above are quite similar to the Chequered Lancer, but the spots are generally larger and more prominent.



The butterfly is considered very rare and its life history has hitherto not been recorded yet. The caterpillar host plant is very likely one of the jungle palms or even rattan, and it is hoped that we can document its full life history one day in the near future.

The Yellow Vein Lancer (Pyroneura latoia latoia)



At a glance, the Yellow Vein Lancer can look quite similar to the Yellow Chequered Lancer. However, upon a closer look, the differences are obvious and the two species can be separated quite easily. The butterfly is another forest-dependent species that is usually found within Singapore's nature reserves. Where found, sometimes several individuals can be spotted in the same locality, especially when the butterflies are feeding on the flowers of the Bandicoot Berry (Leea indica).


A glimpse of the upperside of a Yellow Chequered Lancer as it sunbathes in the warm sunshine


The Yellow Vein Lancer is dark brown on the upperside and the forewing has a series of pale yellow hyaline spots and streaks. The hindwing has a series of hyaline discal spots overlaid by a yellow band. On the underside, the veins are prominently marked in yellow with large spots and streaks between the veins. The antennae are yellowish from the apiculus to just behind the club, and the abdomen is striped black-and-yellow.



The species is moderately common in the nature reserves, and the caterpillars have been successfully bred on the Nibong Palm (Oncosperma horridum) that can be found in forested areas within the Central Catchment Nature Reserves.

The Pugnacious Lancer (Pemara pugnans)



The Pugnacious Lancer is the sole representative of the genus in the Southeast Asian Region. It is very rare in Singapore, and found mainly in forested areas within the nature reserves. Where observed, it is usually perched on the upperside of leaves with its wings folded upright. It is skittish like most skippers and tends to "jump" when it is photographed with a flash.


The upperside of the Pugnacious Lancer, showing the unique arrangement of the forewing spots


The species is dark brown above with a series of pale yellowish hyaline spots on the forewing. The underside is orange-brown and generously overlaid with ochreous scaling on both wings. On the forewing, there is a pair of black sub-apical spots adjacent to a single yellowish hyaline spot. The antennae are blackish brown throughout.


A Pugnacious Lancer perched on the upperside of a leaf with its wings folded upright

The caterpillar host plant of the Pugnacious Lancer is still unknown and given its rarity, it is hoped that a chance encounter of an ovipositing female of the species can fill in the gap in our knowledge of the early stages of this butterfly.

Text by Khew SK : Photos by James Chia, Goh LC, Khew SK, Koh CH, Nelson Ong and Jonathan Soong

Butterfly of the Month - October 2018

Butterfly of the Month - October 2018

The Yellow Glassy Tiger (Parantica aspasia aspasia)

A female Yellow Glassy Tiger feeding on Lantana camara flower

The year 2018 crawls along into its tenth month and October is almost halfway through. It has not been a good year, both at the personal and at the work fronts, and I cannot wait for 2018 to end and to look ahead with greater optimism in 2019. It has been a year of ups and downs (mostly downs) and probably one of the more forgettable years in my life.

The local economy has not been favourable to the industry that I am in, and competition is rife and many companies are facing headwinds and a rather pessimistic outlook in the months to come. Throw in several unfortunate events directly affecting the company's branding and being in the news for the wrong reasons, it has been a year of hard knocks and bruised performances.

Health issues in the family also remind us of our mortality and vulnerability as we age. Time robs us of our youthful exuberance and leaves us a shell of what we used to be. But that's life, isn't it? No one gets younger or healthier as they age. But it is a grim reminder of the fear of losing a loved one, or facing major lifestyle changes due to negative impacts of the body's state of health. No one can say that they are prepared for such setbacks in their lives, because no matter how theoretically prepared we are, in reality, we aren't.

The global outlook is not that rosy either, with the US-China trade wars escalating in a tit-for-tat game of economic battles in the form of trade tariffs resulting in higher costs for some businesses causing overall global uncertainty in the near term. If we take a look back at history, the events preceding the two world wars started with economic crises. So let's hope that history won't repeat itself.

Even Mother Nature seems to be throwing out more extreme weather throughout the year and I don't recall back-to-back severe typhoons whipping Asian countries in recent history, resulting in multiple fatalities where these natural disasters struck. Add a couple of erupting volcanoes, a few earthquakes and tsunamis and hurricanes over in the western continents, it has been a particularly turbulent year for our world in the form of natural disasters too.

A male Yellow Glassy Tiger feeds on the flowers of a roadside White Weed (Ageratum conyzoides)

This month, we feature a seasonal visitor to Singapore, the Yellow Glassy Tiger (Parantica aspasia aspasia). Although recorded in Singapore by the early authors, the Yellow Glassy Tiger is very rare, and has not been seen for many years. Individuals have been irregularly observed from time to time, and these are believed to be strays from southern Malaysia making the occasional visits from across the Straits of Johor.

The Yellow Glassy Tiger's wings are predominantly bluish-grey with narrow black longitudinal streaks across both wings. Each wing has a bright yellow basal patch, with the yellow more extensive on the hindwing. It is this yellow colouration that gives the species its common name and distinguishes it from its all-grey cousins like the more common Blue Glassy Tiger and Dark Glassy Tiger found in Singapore.

The species flies with its characteristic slow and unhurried flight, which is typical of the "Tiger" butterflies of the Danainae subfamily. As the caterpillars of many of the Danainae species feed on lactiferous and toxic host plants, the adult butterflies display aposematic colouration and patterns, and are distasteful to predators.

A male Yellow Glassy Tiger feeding on the flowers of the Golden Dewdrop (Duranta erecta)

A female Yellow Glassy Tiger feeding on the flowers of the Indian Heliotrope (Heliotropium indicum)

The male Yellow Glassy Tiger has narrower and slightly more pointed wings, whilst the female has more rounded wings. The males also possess a conspicuous sex brand at the sub-tornal area of the hindwing. Females may be slightly paler in colour.

A male Yellow Glassy Tiger puddling at a damp streambank

Male Yellow Glassy Tigers have sometimes been observed to puddle at damp sandbanks near forest streams. Both sexes are frequently found feeding at flowering plants and wildflowers along roadsides and jungle trails. Although the species is relatively common in Malaysia but thus far, it is infrequently seen in Singapore.


A female Yellow Glassy Tiger spotted at Gardens by the Bay (Bay East), Singapore in Feb 2014

Locations where the Yellow Glassy Tiger was previously spotted included Hort Park, Alexandra Hospital Butterfly Garden, Pulau Ubin and Gardens by the Bay. Hopefully, this common species in Malaysia may one day make its home permanently in Singapore once again in the near future.

Text by Khew SK : Photos by Sebastian Ho, Khew SK, Loke PF, Anthony Wong and Mark Wong