Catopsilia pomona

Species of butterfly

Catopsilia pomona, the common emigrant The species gets its name from its habit of migration. Some early authors considered them as two distinct species Catopsilia crocale and Catopsilia pomona.

The species has pale and dark morphs in Australia. The form crocale has the antennae black and the form pomona has the antennae pinkish or red. The development of these forms has been linked to photoperiod and temperature during growth.

Quoted from Bingham, C. T. (1907) The Fauna of British India, Including Ceylon and Burma: Butterflies volume 2. "The upperside of the male is chalky white, sometimes with a more or less broad and clearly defined basal sulphur yellow area on both fore and hind wings; this sulphur yellow colour is at times diffused over the whole surface of the wings, though generally it becomes paler towards the terminal margins. For the fore wing, the whole, or sometimes only the apical half, of the costa narrowly black, this color widened out irregularly at the apex; termen widely black at the apex, the colour narrowed posteriorly. This border in some specimens almost reaches the tornus, in others terminates above vein 4; occasionally it is continued posteriorly by a series of block dots at the apices of the veins. Hind wing: generally uniform, unmarked, some specimens bear minute black dots at the apices of the veins.

The eggs of the butterfly are laid on various species of plants including several Cassias. Other host plants include Butea monosperma, Cassia fistula, Bauhinia species, Pterocarpus indicus, Senna alata and Sesbania species. The eggs are usually laid singly on the underside, at the margin of the leaves. Each egg is white, bottle shaped, and ribbed vertically. The eggs hatch in 3–4 days.

The newly hatched caterpillar is about 0.5 cm long and is yellowish green. In later instars the colour changes to a leafy green. The head is green and spotted with tiny black tubercules. The spiracles are covered with a continuous white line. Each segment of the body bears tiny shiny black tubercules. The tubercules immediately above the spiracular line being larger and more distinct giving the effect of a black line over the white spiracular line. The paired lines are found on both sides of the body and run from head to anus. The similar Catopsilia pyranthe caterpillar has a much broader black line leaving only a narrow green line on the back of the body. The larva is described by Thomas Reid Davys Bell as "The head is round, green, the clypeus edged with brown, covered with small shiny black tubercles which do not hide the colour of the head; the anal flap is rounded, but looks square at the extremity, and is covered with rows of small black tubercles of which only the row along the spiracular line is conspicuous. The spiracles are oval, shiny and white. The colour is green with a spiracular white band touched with bright yellow on segments 2 5, and these segments, especially 3 and 4, are distinctly flanged on the spiracular line. Length 51 mm.

Pupation takes place low to the ground. The pupa is suspended by a silken body band and attached to the substrate by a black cremaster. Its entire body is bright leaf green. A continuous yellow runs from the cremaster to the head, the head ending in a snout. In the similar Catopsilia pyranthe the snout is short. The pupa is described by Bell as "The pupa has the dorsal line of the thorax absolutely parallel to the longitudinal axis of the pupa for two thirds of its length, consequently the hinder part just before the margin is perpendicular to this part, it is raised suddenly but very slightly above the front margin of segment 4, and the front end of this parallel dorsal line is at an angle, and a sharpish angle, with the front slope of the thorax the cremaster is distinctly bifid at the extremity, and has some shiny, very stout, black, suspensory hooks dorsally as well as at the extremity. There is a dorsal rugose black tip to the snout terminating the head, which snout is cylindrical in its apical half; there is no black line round the eye and there is a dark green blue dorsal line which is yellow on the thorax as well as the supra spiracular yellow line. Length 34 mm; length of snout 3 mm; breadth at segment 7 is 9 mm; height at apex of curve of wing (segment 6) 10 mm; height at apen of thorax 8 mm".