Butterflies of Singapore: Life History of the Common Yeoman

Life History of the Common Yeoman (Cirrochroa tyche rotundata)

Butterfly Biodata:
Genus: Cirrochroa Doubleday, 1847
Species: tyche C & R Felder, 1861
Sub-species: rotundata Butler, 1879
Wingspan of Adult Butterfly: 50-60mm
Caterpillar Local Host Plants: Hydnocarpus castanea (Achariaceae), Hydnocarpus alpina (Achariaceae).

A male Common Yeoman puddling on wet ground.

A pristine male Common Yeoman resting on the underside of a leaf.

Another puddling male Common Yeoman.

Physical Description of Adult Butterfly:
On the uppersdie, the wings are tawny orange with black distal margin, sinuate marginal and submarginal lines. The hindwing has a series of black post-discal spots. The female is duller orange with black margin at the forewing apex broader than that in the male. On the underside, the wings are paler orange in the male and dull brownish orange in the female. Both wings feature a silvery white transverse discal band.

A female Common Yeoman resting on a perch.

A female Common Yeoman showing us its upperside.

A female Common Yeoman sunbathing on a perch in between oviposition flights to the host plant nearby.

Field Observations of Butterfly Behaviour:
This newly discovered species has so far been sighted at two locations in Singapore. The adults are rapid in flight and not easy to photograph. Typically, photography opportunities arise when the males are puddling on wet ground, or when the females are taking breaks between oviposition runs.

Another Common Yeoman on a leaf-perch.

Early Stages:
Caterpillars of the Common Yeoman have been observed to feed mainly on young to middle-aged leaves of the two local host plants, Hydnocarpus castanea and Hydnocarpus alpina. It is likely that other members of the Hydnocarpus genus could serve as larval hosts for the Common Yeoman.

Local host plant: Hydnocarpus castanea.

A mating pair of the Common Yeoman (female left, male right).

The eggs of the Common Yeoman are laid singly or in small groups of 2 to 3 on the leaf underside or young shoots of the host plant. Sometimes eggs can be found laid on the cobweb present on the leaf underside. The pale whitish to yellowish egg is somewhat globular in shape but with a blunt top. The surface is marked with small rectangular to hexagonal pits. Each egg has a diameter of about 0.8-0.85m, and a height of about 0.85-0.9mm.

Two views of an egg of the Common Yeoman.

A pair of eggs laid on cobweb.

Left: maturing eggs. Right: one mature egg adjacent to an half-eaten egg shell.

The egg takes about 2.5 days to hatch. The young caterpillar emerges by eating away part of the egg shell. The rest or part of the remaining egg shell becomes the first meal for the newly hatched which is about 2.2mm in length. It has a cylindrical and pale pinkish body covered with many small tubercles and long setae. The head capsule is coloured as per the body and has two large black lateral patches.

Two views of a newly hatched caterpillar of the Common Yeoman, length: 2.2mm.

The 1st instar caterpillar feeds on the lamina of young leaves and between feeds, it typically rests on leaf underside against the midrib. The body colour takes on a pale yellowish green undertone as it grows. After reaching about 4-4.2mm in 1.5-2 days, the caterpillar moults to the 2nd instar.

Two views of a 1st instar caterpillar, length: 3mm.

The body of the 2nd instar caterpillar is yellowish brown. Long and branched dark-brown to black processes run along the length of the body. On each side of the body, there are three series of such processes: One series occurs dorso-laterally, another lateraly and the last sub-spiracularly. The head capsule is black entirely. This instar lasts about 1-1.5 day with the body length reaching about 6-6.5mm.

Two views of a 2nd instar caterpillar, early in this stage, length: 4.2mm

Two views of a 2nd instar caterpillar, early in this stage, length: 5mm

The 3rd instar caterpillar has the dorso-lateral and lateral processes proportionately longer and black in color. The body is dark yellowish brown with a slight green undertone. The head capsule is still black in colour. This instar takes about 2 days to complete with body length reaching about 9-10mm.

Two views of a 3rd instar caterpillar, early in this stage.

Two views of a 3rd instar caterpillar, length: 8mm.

The 4th instar caterpillar closely resembles the 3rd instar caterpillar. It has proportionately longer processes when compared those in the 3rd instar. The head capsule is still entirely black in this penultimate instar. The 4th instar lasts about 2 days with the body length reaching about 15-16mm.

Two views of a 4th instar caterpillar, early in this stage, length: 10mm.

Two views of a 4th instar caterpillar, length: 16mm.

A 4th instar caterpillar observed feeding on the underside of a young leaf in the field.

The 5th (and final) instar caterpillar is similar to the 4th instar caterpillar. The body base colour is still pale yellowish brown, but there are numerous dark brown patches on the body and together with the prominent dark circular bases of the spiny processes give the caterpillar a dark brown appearance. The most specimens, the head capsule is still entirely black, but in some specimens, the black border at the upper rim recedes and coloration there turns pale yellowish brown.

A newly moulted 5th instar caterpillar.

Two views of a 5th instar caterpillar, length: 26mm.

The frontal view of a 5th instar caterpillar, showing the black head capsule and spiny processes.

The 5th instar lasts for 3.5-4 days, and the body length reaches up to 26-27mm. On the last 0.5 day, the body shortens and decolorizes to pale beige brown. The caterpillar ceases feeding and wanders around. Eventually it stops at a spot on the underside of a leaf, and spins a silk pad from which it hangs vertically to take on the pre-pupatory pose.

A late stage caterpillar of the Common Yeoman seen in the presence of a female adult in the field.

Two views of a pre-pupa of the Common Yeoman.

Pupation takes place about 0.5 days later. The pupa suspends itself from the silk pad via the cremaster attachment. It is almost entirely whitish or pale yellowish brown. Dorso-laterally, along the body length, there are pairs of white-tipped, curled processes, one to each segment. These processes are mostly orange basally and black below the tip. Two additional pairs of prominent processes are present laterally on the 3rd and 4th abdominal segments. Length of pupae: 16-18mm.

The pupation event of a Common Yeoman butterfly

Two views of a pupa of the Common Yeoman.

Two views of a mature pupa of the Common Yeoman.

After about 3.5-4 days of development, the pupal skin of the mature pupa turns translucent and the orange wing upperside become discernible in the wing case as a result. The eclosion event takes place the next day, typically in the evening.