19 November 2011

Life History of the Lime Butterfly v2.0


Life History of the Lime Butterfly (Papilio demoleus malayanus)



Butterfly Biodata:
Genus: Papilio Linnaeus, 1758
Species: demoleus
Linnaeus, 1758
Subspecies: malayanus
Wallace, 1865
Wingspan of Adult Butterfly: 60-80mm


Caterpillar Local Host Plants:
  Citrus microcarpa (Rutaceae), Citrus maxima (Rutaceae, common name: Pomelo), Citrus aurantifolia (Rutaceae, common name: Lime) and other Citrus spp., Ruta graveolens (Rutaceae, common name: Herb-of-grace).


A male Lime Butterfly.


A female Lime Butterfly.

Physical Description of Adult Butterfly:
Above, both sexes are black with yellow spots and markings, some of which forming  an  irregular and intermittent macular band running across the forewing to the mid-dorsum of the hindwing.  A submarginal series of smaller yellow spots can be found on both wings. In space 1b on the hindwing, there is a red spot in both sexes. In the male, this spot is capped with a narrow blue lunule with a very narrow intervening black gap. In contrast, the red spot and the blue lunule in the female have a  rather large black spot between them.  Underneath, both sexes are mostly yellow with black streaks and irregularly-shaped spots.  On the hindwing, several black spots are lined with blue striae. There is  a series of orange post-discal bars on both hind- and forewings.






Field Observations of Butterfly Behaviour:
Lime Butterfly is rather common in Singapore and can be found in both forested and urban areas in Singapore. The fast flying adults are frequently seen in flights in and around residential areas, often  visiting flowers growing in gardens and  potted plants  in common areas outside houses/flats.  The females can also be seen making ovipoisiting visits to the many Citrus plants, cultivated or wild, in the residential neighbourhood. The hyper-active adults are easier to approach for photographic captures during the cooler hours in the morning and late afternoon, when they retire to rest among the foliage. 




Early Stages:
The local host plants include a number of species in the Rutaceae family, with majority belonging to the Citrus genus.   The caterpillars of the Lime Butterfly feed on the young to middle-aged leaves of the host plants.

Host plant : Citrus aurantifolia.


A mating pair of the Lime Butterfly.

The eggs of the Lime Butterfly are laid singly on the young stem, the petiole or the underside of leaves of the host plant. The egg is pale creamy yellow with a finely roughened surface. It is nearly spherical with a diameter of about 1.1-1.2mm.


A mother Lime Butterfly about to oviposit on a lime plant.


Two views of an egg of Lime Butterfly, diameter: 1.1-1.2mm


Two views of a mature egg of the Lime Butterfly.

The egg takes about 2.5-3 days to hatch. The young caterpillar eats its way out of the mature egg, and then proceeds to finish up the rest of the egg shell. The newly hatched has a body length of about 2.75mm and has a rather spiky appearance caused by bands of spiky processes which are longer dorso-laterally and much shorter laterally. Overall the body  is yellowish brown dorsally and darker brown laterally. The head is dark brown.


Two views of a new hatched caterpillar nibbling at the egg shell.

The first 4 instars of the Lime Butterfly  resemble bird droppings with the resemblance in the 3rd and 4th instars being closer due to  the body  taking on  a slimy appearance. As the 1st instar caterpillar grows up to a length of about 5mm, the  whitish saddle patch on the 3rd-4th abdominal segments become more evident. After about 2.5-3 days in 1st instar, the caterpillar moults to the next instar.


Two views of a 1st instar caterpillar, late in this stage,  length: 4.8mm

The 2nd instar caterpillar has a similar appearance to the late 1st instar caterpillar except for the more prominent whitish saddle. As the caterpillar grows, small whitish patches appear laterally on the first two thoracic segments. This instar lasts about 2 days with the body length reaching up to  10mm before the next moult.


Two views of a 2nd instar caterpillar, newly moulted, length: 4mm


Two views of a 2nd instar caterpillar, late in this stage, length: 7mm

The 3rd instar caterpillar has whitish lateral patches on the anterior and posterior body segments. The white saddle is  more extensive and prominent than in the two previous instars.  This instar takes about 2 days to complete with the body length reaching up to 16mm.


Two views of a 3rd instar caterpillar, early in this stage, length: 10.5mm


Two views of a 3rd instar caterpillar, late in this stage, length: 16mm

The 4th instar caterpillar resembles the late 3rd instar caterpillar initially but with a more slimy appearance and a ground colour which is in darker brown.  This penultimate instar lasts about 2-2.5 days with body length reaching about 25mm.
 

Two views of a 4th instar caterpillar, newly moulted, length: 15.5mm


Two views of a 4th instar caterpillar, late in this stage, length: 25mm

The next moult brings the caterpillar to its 5th and final instar with a drastic change in appearance. There are two lateral eye spots near the leading edge of the  third thoracic segment with a   milky brown transverse band linking them. Another transverse band can be found at the posterior edge of the same body segment. A long oblique bar, dark brown in colour, stretches from the base of the 4th abdominal segment to the dorsum of the 5th abdominal segment. A much shorter  bar can be found in the 6th abdominal segment. Round dorso-lateral marks, variable in size, can be found on the 6th to the 8th abdominal segments.  After the moult to 5th instar, the body ground color is initially mottled  yellowish green, but this changes gradually to a uniform green or yellowish green after about 0.5 day.


Two views of a 5th instar caterpillar, freshly moulted, length: 23mm.


Two views of a 5th instar caterpillar, late in this stage, length: 41mm


Two views of another 5th instar caterpillar, late in this stage, length: 39mm

As in the case of all Swallowtail butterflies, the Lime Butterfly caterpillars in all instars possess a fleshy organ called osmeterium in the prothoracic segment. Usually hidden, the osmeterium can be everted to emit a foul-smelling secretion when the caterpillar is threatened.


The 5th instar lasts for about 3.5-4  days, and the body length reaches up to 41mm. Toward the end of this instar, the body gradually shortens in length. Eventually the caterpillar comes to rest on the under surface of a stem or a leaf. Here it stays dormant for a while before performing a purge of  loose and wet frass pellets. It then spins a silk pad and a silk girdle to become an immobile pre-pupatory larva.


A pre-pupatory larva of the Lime Butterfly.
 
A Lime Butterfly caterpillar molts to its pupal stage.

Pupation takes place a day later. The pupa suspends itself with a silk girdle from the substrate. There are two color forms. In the green form, the pupa is is mainly green with a large yellowish diamond-shaped patch on the dorsum of the abdominal segments.. In the brown form, the pupa is mainly greyish  brown with dark patches. Each pupa has a pair of cephalic horns, a dorsal thoracic hump and is angled in side view. Length of pupae: 30-32mm.


Two views of a Lime Butterfly pupa, brown form.


Two views of a Lime Butterfly pupa, green form.

After 9 days of development, the pupa turns black as the development within the pupal case comes to an end. The yellowish spots and band on the forewing becomes visible through the pupal case. The next day the adult butterfly emerges from the pupal case. The beautiful undersides of its wings are fully displayed as it dries its wings for the first one to two hours after eclosion.

Two views of a mature pupa.

A Lime Butterfly adult emerges from its pupal case.


A newly eclosed Lime Butterfly clinging onto its pupal case.

References:
  • [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 1st Edition, 2006
Text by Horace Tan, Photos by Tan Keyang, Bobby Mun, Loke PF,  Sunny Chir, Khew SK and Horace Tan