11 November 2007

Life History of the Purple Duke (Eulaceura osteria kumana)



Butterfly Biodata :
Genus : Eulaceura Butler [1872]
Species : osteria (Westwood, [1850])
Subspecies : kumana (Fruhstorfer, 1913)
Wingspan of Adult Butterfly : 60mm
Caterpillar Host Plant : Gironniera subaequalis

Physical Description of Adult Butterfly : The forewing of the adult butterflies is strongly falcate and the hindwing produced at the tornus. Males are pale purple brown above with a white discal fascia. The female is dull ochreous brown with obscure while fasciae in the distal halves of both wings.

Field Observations of Butterfly Behaviour : Adult butterflies often fly rapidly along jungle paths and settle upside down on the undersides of leaves with their wings folded shut. When disturbed, the butterfly will zip off and display the same behaviour on the next leaf, usually flying short distances. In the early morning hours, both the males and females are more likely to stop on the uppersides of leaves with wings opened flat to sunbathe.

Early Stages :

The female oviposits a single egg, usually on the underside of a leaf of the host plant. The egg is pinkish in colour, almost round with vertical ribs running down the length of the egg.
Egg of the Purple Duke (Eulaceura osteria kumana)

After about 3 days, the caterpillar hatches from the egg, and immediately starts to consume the eggshell completely. The caterpillar then searches for the younger leaves of the host plant and starts to eat the softer young shoots on the host plant.

The 1st instar caterpillar has a smooth round head with lateral dark and light green stripes running the entire length of its body. It has a forked 'tail' which is a feature of this species in all the instars.
1st instar Purple Duke caterpillar with its smooth rounded head

As it moults into the 2nd instar, the lateral green stripes are still there, but the head now takes on forked processes which are dark in colour, giving it an appearance of having 'antlers'. The caterpillar tends to hide on the undersides of the leaves of the host plant.
2nd instar caterpillar showing the black "antlered head" and forked tail.

In the 3rd instar, the black 'antlers' are now more defined, but with light pink extremities. The green stripes of the early two instars are now replaced with two lateral green bordered yellow stripes running down the side of the caterpillar's body. There is a pattern of yellow spots over the entire body.
3rd instar caterpillar showing its black antlered head and sporting yellow/green spotted markings on its body.

The 4th instar caterpillar is essentially similarly patterned as the 3rd instar, but the forked 'tails' are longer and the 'antlers' have now taken a light salmon colouration. The caterpillar remains on the underside of the host plant's leaf when not eating, and carefully aligns itself with a leaf rib such that it camouflages itself very well.
4th instar caterpillar with its salmon-coloured "antlers"

The 5th and final instar caterpillar sports two lateral salmon-coloured stripes which start from the base of the 'antlers' and runs the entire length of the body to the forked 'tails'. Alternate transverse light and dark green bands can also be seen running down the body of the caterpillar, perpendicular to the lateral stripes.



5th instar caterpillar Note the twin lateral stripes. Inset : Close up of the caterpillar's head.

After a total of 38 days upon hatching from the egg, the caterpillar then goes into a day of dormant pre-pupation pose. The caterpillar prepares for pupation by anchoring itself well on the underside of a leaf. Unlike many other species which has a girdle to support the pupa, or where the caterpillar curls up in a pre-pupation pose, the caterpillar of the Purple Duke remains flat on the underside of the host plant and keeps a low profile staying very close to the leaf.
Pre-pupation pose of the caterpillar. It remains dormant in this position for about 24 hours.

The pupa is light green with a single yellow lateral stripe down the back of the pupa. The head takes on a short horned appearance. The pupa hangs from its cremaster with its head facing downwards.

Pupa of the Purple Duke. On the left photo, note the head of the caterpillar discarded as it transforms from a biting/chewing caterpillar into a pupa within which the process of metamorphosis changes it into a nectar-sucking butterfly with no biting mouth parts.

After about 8 days, the pupal shell turns transparent and the wings of the soon-to-be-emerging butterfly can be seen through the pupal shell. A few hours before eclosion, the pupa turns a warm beige with the wings becoming darker and more pronounced and distinctly visible through the pupal shell.
All ready for eclosion. The wing patters of the adult butterfly can be seen through the now transparent pupal case.

Finally, in the late morning, the adult butterfly ecloses and hang its wings out to dry, as it pumps fluids into the wings to expand them. It stays for about an hour or more to ensure that its wings are sufficiently dried and hardened before it takes its maiden flight to search for its mate and continue the circle of life.



Text and Photos by Khew SK

6 comments:

Kevin said...

Excellent detailed post! have linked ur blog in mine :) keep up the good work!

Ha I have trouble even trying to hatch lime caterpillars on my houseplants. how do you ensure the caterpillar adheres itself to a correct place in a closed container? I gave up after two failed attempts so i jus let nature take its own course so far one butterfly was born that way.

Commander said...

Thanks for your comments, Kevin. :) One of our members recorded a nice life history of the Lime Butterfly recently.

In a closed container you have to monitor that it has reached its 5th instar and provide some twigs as perches for the pupating caterpillar. Otherwise it will stick to the sides or cover of your container and not provide a very natural setting for photography. ;)

Atsushi said...

Hi Commander,

My name is Atsu. Your pictures and in-depth stories about butterflies are really resourceful and helpful!
After reading a book, white map of swallow tail butterfly, written by 五十嵐 邁(Suguru Igarashi), one of well known Japanese butterfly specialists, I became very interested in this Purple Duke butterfly be cause at the last capture of his book, he concluded the book with the story of this butterfly in SIngapore!
I would like to raise this butterfly and make an observation, but I don't know how I can find its host plant, Gironniera Subaequalis. I googled it, but I haven't gotten the luck to find good resource to see how this plant looks like.... It will be truly appreciative if you give me some advice to find this host plant to raise this butterfly. This is the information of Mr. Suguru Igarashi's book's information. http://www.amazon.co.jp/アゲハ蝶の白地図-五十嵐-邁-いがらし-すぐる/dp/4418085017

Yours,
Atsushi

Commander said...

Hi Atsushi,

Yes, I have the two volumes of Igarashi-san's books. The host plant is a forest plant and is not sold commercially. Although the plant is common in many places in the nature reserves of Singapore. I am not sure if I can find the seeds or not, but maybe I can try.

If you are in Japan, it may be difficult for you to get the host plant.

Atsushi said...

Thank you very much for your thoughtful reply to my inquiry. Luckily, I am now living in Singapore!
So I want to find this host plant to raise the caterpillar to observe how this butterfly grows.
I tried to find the picture of this plant, but all the information was just written words and small tiny pictures at best.

I am thinking of going to the botanical garden.
Maybe, they might have the trees in the garden.

By the way, I really love Singapore and enjoyed the nature reserve hiking over the weekends. This is my first time to spend my life in the tropical climates. So everything I see here looks so magical, very different from the nature of Japan. Every butterflies appears really fascinating!!


Yours,
Atsushi
Again, thank you for your suggestion.

amalia nina said...

Hi I am from Indonesia, exactly Bangka island. Can I take some your words in my last task? Thank you.