Mistletoes and Butterflies

Mistletoes and Butterflies
Ecological importance of Parasitic Plants

A female Banded Royal opens its wings to sunbathe. A recent addition to the number of butterfly species whose caterpillars feed on mistletoe

A parasitic plant is a plant that derives some or all of its nutritional requirement from another living plant. All parasitic plants have modified roots, called haustoria, which penetrate the host plant, connecting them to the conductive system – either the xylem, the phloem, or both. This provides them with the ability to extract water and nutrients from the host. Parasitic plants which derive water/nutrients from the hosts and are photosynthetic are known as "hemiparasites".


The large leaves of the Malayan Mistletoe are able to support the big numbers of the common urban species like the Painted Jezebel.

There are currently 10 known species of parasitic plants extant in Singapore. Quite a few of these species, commonly referred to as "mistletoes", can be seen attached to a variety of host plants - from shrubs to large trees all around Singapore. Mistletoes are believed to have medicinal properties and used in traditional medicine to cure a variety of ailments like cough, diabetes, hypertension, cancer and as a diuretic.


In the popular Asterix and Obelix comics, the druid Getafix adds mistletoe as a key ingredient in his magic potion 

In the popular comic series Asterix and Obelix, the mistletoe is a key ingredient in the magic potion that endows our two heroes with superhuman strength. The druid Getafix, who makes the concoction, is often depicted in the comics cutting mistletoe, hidden amongst the lush treetops with a golden sickle that preserves the magical properties of the mistletoe.


The hemiparasitic Chinese Mistletoe attached to the host

Parasitic plants are not the most welcomed plants amongst arborists, tree maintenance personnel and gardeners. This is because, by virtue of the parasitic nature of these plants, they anchor themselves to a host shrub or tree and extract nutrients from the host. In very severe infestations, the parasitic plants may stunt the growth of the host or even kill it. However, in most cases, a host can support these parasitic plants for decades without significant adverse effect on the host. Nevertheless, these under-appreciated and misunderstood parasitic plants are often pruned and removed from the host.


The shiny leaves of the Rusty Mistletoe are reddish brown when young, but turn a deep green when mature

What then, are the ecological functions of these "parasites" of other plants? Plants research has shown that mistletoes are keystone species in forests and woodlands. A keystone species is one which has a very significant influence in an ecosystem, and if removed may cause undesirable impact to the ecology. Many birds, insects and aboreal mammals build their nests among mistletoes. A wide variety of animals and insects feed on the leaves, shoots, fruits, flowers and nectar of mistletoes.


The Singapore Mistletoe Story by Francis Lim - a book about the parasitic plants in Singapore

Amongst the species of mistletoes in Singapore, three are of particular importance to butterflies. They are host plants to a variety of common to very rare species of butterflies. This article explores these species of mistletoes which are hosts to the caterpillars of these butterflies. It is also likely that the remaining 7 species of mistletoes may be caterpillar host plants for other species of butterflies, but this has yet to be discovered and hopefully recorded in time to come.

1. Malayan Mistletoe (Dendrophthoe pentandra)


The lush green leaves of the Malayan Mistletoe with flowers on its stem

The Malayan Mistletoe is by far the most common mistletoe in Singapore. It is a familiar site on roadside trees and in urban gardens, especially where plants are neglected or unkempt. It is quite often seen on plants like the Shui Mei (Wrightia religiosa) in private gardens, as well as any urban trees where birds spread the seeds of this parasitic plant, ranging from fruit trees like mango and chiku, to a wide variety of other roadside trees.







This common parasitic plant is a caterpillar host plant to at least five different species of butterflies across three families. These are :

1. Painted Jezebel (Delias hyparete metarete)
2. Green Baron (Euthalia adonia pinwilli)
3. (Tajuria dominus dominus)
4. Peacock Royal (Tajuria cippus maxentius)
5. Great Imperial (Jacoona anasuja anasuja)

The distasteful Painted Jezebel's caterpillars have somehow managed to sequester the chemicals from the Malayan Mistletoe to make itself unattractive to predators

Amongst these species, it is interesting to note that the aposematic Painted Jezebel is believed to be distasteful to birds and has somehow managed to sequester the chemicals in the Malayan Mistletoe as a protection against predators. This is something that the other 3 species that feed on the same host plant are not able to do so, or at least the adult butterflies are not known to be distasteful to predators.


The flowers of the Malayan Mistletoe

The Malayan Mistletoe is most likely dispersed mainly by the birds that feed on its fruits, and then transporting the seeds to other trees where the bird droppings, which contain the seeds, are deposited on the branches of other plants. As the seeds ripen, it will extend its haustoria (specialised roots) and penetrate into the host as it takes grip and grows. The haustoria of the Malayan Mistletoe tends to grow into a ball-like form as the plant matures.

2. Chinese Mistletoe (Macrosolen cochinchinensis)


A healthy growth of the Chinese Mistletoe

The next most common species of our local parasitic plants, is the Chinese Mistletoe, which, like the previous mistletoe, is also a stem hemiparasite. It attaches itself to the branches of its host and grows into a large bush that can span 1m-2m across. Depending on the size of the host, the growth of the Chinese Mistletoe can sometimes overwhelm and smother the entire host.










The Chinese Mistletoe is a caterpillar host plant to an even wider variety of butterfly species (some of which also feeds on the Malayan Mistletoe). These are :

1. Green Baron (Euthalia adonia pinwilli)
2. Centaur Oakblue (Arhopala centaurus nakula)
3. Peacock Royal (Tajuria cippus maxentius)
4. Banded Royal (Rachana jalindra burbona)
5. Felder's Royal (Tajuria mantra mantra)
6. Green Imperial (Manto hypoleuca terana)
7. Great Imperial (Jacoona anasuja anasuja)
8. Semanga superba deliciosa.

The flowers and fruits of the Chinese Mistletoe, on which the caterpillars of the Green Imperial and Banded Royal feed

The leaves of the Chinese Mistletoe are pinkish to red when young, turning light green and finally dark green as they mature. The mature leaves are stiff and slightly waxy. It should be noted, however, that several of the butterfly species' caterpillars actually feed on the flower buds and fruits of the Chinese Mistletoe, rather than the leaves.


A young shoot of the Chinese Mistletoe attached to its host via its specialised roots called haustoria

Like the Malayan Mistletoe, the Chinese Mistletoe is also mainly propagated by birds. Birds feed on the ripened globular fruits of the Chinese Mistletoe and once digested, the bird droppings are deposited on other plants as the bird moves in search for food. This gives a chance for the seeds to germinate and grow if a suitable host is found.

3. Rusty Mistletoe (Scurrula ferruginea)


The Rusty Mistletoe has a layer of fine brown hairs on the undersides of its leaves - giving it a "rusty" look

The last and slightly rarer species of mistletoe that plays host to butterfly caterpillars, is the Rusty Mistletoe. The leaves of this parasitic plant are green on top, but covered with a layer of fine brown hairs on the underside of the leaves, giving it a "rusty" appearance. As it grows, the main stem of the Rusty Mistletoe attaches to the host rather seamlessly, with a few side roots extending along the sides of the branch, growing the many little haustoria into the host.



The White Royal's caterpillars feed on the young shoots and leaves of the Rusty Mistletoe

This species of mistletoe is the caterpillar host plant for at least two species of Lycaenidae. These are:

1. Great Imperial (Jacoona anasuja anasuja)
2. White Royal (Pratapa deva relata) 

Both are rare species in Singapore. The White Royal was only recently re-discovered in 2007 but subsequently successfully bred on the Rusty Mistletoe.  The Great Imperial, which has been bred on all three mistletoes mentioned in this article, is the most versatile and its caterpillar accepts all three host plants.


A female White Royal perched on a leaf of the Rusty Mistletoe after ovipositing on the young shoots of the plant

Where it grows, the Rusty Mistletoe is not difficult to spot, as the brownish red appearance of its foliage sets it apart from its host. It grows into a relatively large bush that can measure 1-2m across. The flower of the Rusty Mistletoe has an interesting appearance of a brownish coloured hairy paw, whilst the fruit is a small hairy pseudo berry of about 1cm long.



Again, like the other mistletoes mentioned here, the Rusty Mistletoe is probably dispersed by birds that eat the fruits and then propagated by the bird droppings as the birds forage for food around the area. The seeds are also likely to stick onto branches of the host and then the haustoria anchoring the the plant to the host after the seed germinates, typical of the like the other species of stem hemiparasites.



In closing, we have taken a look at the more common mistletoes found in Singapore, and it is through keen observations with a dose of luck that we have discovered the range of species of butterflies that are dependent on these specific mistletoes for survival. If there is overzealous management of these "parasites" and their removal from their hosts, then it will critically threaten the existence of these species of butterflies (many of them rare) in Singapore. So the next time you see these parasitic plants around, leave them alone. The butterflies will thank you for that!

Text by Khew SK : Photos by Huang CJ, Khew SK, LohMY, Jonathan Soong and Horace Tan

References and Further Reading :

• A Guide to the Common Epiphytes and Mistletoes of Singapore 
• The Singapore Mistletoe Story: An Expose of a Botanical Marvel
• Mistletoes of Singapore
  

Flight of the Imperials

Flight of the Imperials

Featuring Singapore's Imperial Butterflies


A Branded Imperial perches on a leaf in the shaded forest understorey

The English word "imperial" is usually used to refer to things or people that are or were connected with an empire or pertaining to an emperor or empress. When the early collectors coined the name Imperial for some species of the Lycaenidae family, it is highly likely that they were using the word to describe these majestic butterflies that awed them with their breath-taking colours and beauty.


A Green Imperial stops to rest on the flower of the Javanese Ixora

In the world of butterflies, the Imperials are pretty, colourful and usually long-tailed species belonging to the sub-family Theclinae of the Lycaenidae family. Singapore is home to five of these Imperials, all of which are forest-dependent and usually found only in the heavily forested nature reserves. Of the five, only one is considered common and regularly seen by nature enthusiasts.


A female Great Imperial feeding on the flower of the Javanese Ixora

This blogpost takes a look at these five Imperial butterflies found in Singapore. Interestingly, each one of the five belongs to a different genus. All have orange with white undersides and black tornal markings. Their long tails are remarkable features on these species, and two of them probably sport the longest tails amongst the extant butterflies in Singapore.

1. The Branded Imperial (Eooxylides tharis distanti)


A Branded Imperial shares the sweet sap of the Bandicoot Berry with some ants

The first of the Imperials is the Branded Imperial. This species is by far the commonest of the five species and is regularly found along forest paths in the shaded understorey of our nature reserves. At times, several individuals can be seen together, particularly when they are feeding on the young shoots of the Bandicoot Berry (Leea indica).



A male Branded Imperial opens its wings to sunbathe.  Note the prominent brands on its forewings

The wings are black above with blue-dusted tornal area on the hindwing. In the male, a prominent "brand" can be seen on the upperside of the forewing. This could be why the butterfly is named Branded Imperial. The underside is reddish-orange with the hindwing bearing black sub-marginal spots on the white tornal area. There are 3 tails on the hindwing, of which the one along vein 2 is the longest.



The species' caterpillar feeds on the invasive weed Smilax bracteata which it shares with another Lycaenid, the Yamfly. As this non-native weed is very widespread in the nature reserves (despite efforts to remove the weed), the Branded Imperial has become a common species in Singapore.

2. The Common Imperial (Cheritra freja friggia)



The Common Imperial is a moderately rare species but is quite widespread across the island. Although found in the forested nature reserves, it can sometimes be found in urban parks and forested ridges in Singapore. It is usually observed singly and prefers to stay at treetops. It has a habit of perching on favourite leaves and returns time and again to the same perches as it flies around.


A male Common Imperial sunbathing with its wings opened to show the purple-blue uppersides

The male Common Imperial has purple-blue forewings on the upperside, whilst the female is dark brown. There are large black spots on the tornal area of the hindwing. Te underside is mainly white, with part of the forewing and the apical area of the hindwing shaded a light orange. The tornal spots on the hindwing are overlaid with metallic blue-green scaling. It has 3 tails of which the one at vein 2 is the longest.



The species' caterpillars feed on two species of common roadside trees, the Wild Cinnamon and the Red Saga. It has also been bred on other forest plants that are mainly found in the nature reserves. The species is observed to sunbathe with open wings at certain hours of the day at sunlit spots.

3. The Green Imperial (Manto hypoleuca terana)



The Green Imperial is considered rare in Singapore. It is usually seen at the forest edges of the nature reserves, feeding on the nectar of flowering plants. It is a fast-flying species that probably prefers to stay at the treetops.



The male of the Green Imperial is a shining bluish-green above, with broad black apical area on the forewing. The underside is largely orange and unmarked on the forewing, whilst the hindwing has black sub-marginal spots and streaks. The female is dark blackish-brown above with the usual black spots on a white tornal area on the hindwing. The underside of the dorsal area of hindwing is white, whilst the other areas of the forewing and hindwing are orange. The species has 2 tails - a relatively long tail and vein 2 and a short stubby one at vein 3.



Female Green Imperial. Top : Underside Bottom : Upperside

The species is one of several rare Lycaenidae that feeds on the parasitic plant, Macrosolen cochinchinensis, that can be found growing on large trees and bushes all around the island. The females have been observed ovipositing on the leaves of the host plant in the early afternoon and lays her eggs on the young shoots of the plant.

4. The Great Imperial (Jacoona anasuja anasuja)



Another rare Imperial, the Great Imperial has been observed only in the forested nature reserves of Singapore. The adult butterfly appears to be another tree-top dweller but occasionally can be seen to descend to low level shrubbery to feed or oviposit. When disturbed, it can fly rapidly up the treetops.



Top : Female Great Imperial Bottom : Male Great Imperial

The male of the Great Imperial is a deep shining blue on the upperside with an oblique band running across the apical area of the forewing. The female is predominantly brown above with a white tornal area on the hindwing. The underside is mainly orange with the forewing apical area a darker shade. The dorsal area of the hindwing is white with the tornal black streaks and spots. Both sexes have tails, where the males have a shorter sword-like tail at vein 2 whilst the female's tail is much longer.



The caterpillar host plant of the Great Imperial is the common Malayan Mistletoe. However, the species is not usually found in urban parks and gardens. It is found along the forest fringes and where it is observed, it is perched on the uppersides of leaves with its wings folded upright. Both sexes also descend from the treetops to feed on flowering plants.

5. The Grand Imperial (Neocheritra amrita amrita)



The last of the Imperials is also a rare forest-dependent species that is quite local in distribution. Its caterpillar host plant is found in the nature reserves and is quite rare. The plant has yet to be positively identified. However, the Grand Imperial was seen in numbers on the military-training island of Pulau Tekong in the early 2000's during a period of biodiversity surveys. It is not known if they are currently still as common.


A male Grand Imperial feeding on flowers

The male Grand Imperial has a royal blue upperside, with the apical areas of both wings black bordered. The female is dark brown and largely unmarked, except at the white tornal area where there are black spots. The underside of the forewing and costal half of the hindwing is dark orange whilst the remaining part of the dorsal area of the hindwing is pure white.


A female Grand Imperial sunbathing

The Grand Imperial has the longest tails of any Lycaenidae found in Singapore. It has 3 tails, of which the longest tail is at vein 2, whilst there are two shorter tails at veins 1b and 3 of the hindwing. The male has a prominent raised 'disc' on the underside of the forewing.

Text by Khew SK : Photos by Huang CJ, Khew SK, Simon Sng, Jonathan Soong, Horace Tan and Tea Yi Kai