Host: This is a common pest of all citrus plants.
Damage: Larvae are voracious feeders of tender leaves and defoliate the trees. They eat leaves from margin inwards, leaving the larger veins intact. Younger plants cannot withstand defoliation and die.
Life cycle: Adult is a large butterfly having a wingspan of 7-8 cm. It has prominent black and yellow markings on the wings. Hind wing has a crimson spot on the tail on dorsal side and a ring-like eye spot on the anterior margin on the ventral side. They are active fliers and found throughout the year in plains. Fecundity is 80-150 eggs. Eggs are small, round, smooth, yellowish and laid singly glued on to the tender leaves. They hatch in 3-6 days.
First three instars of the larvae resemble bird droppings as they are brownish-black in colour, with one or two white patches. Last two instars are green in colour, sometimes with greyish markings, 3-4 cm long and stout anteriorly, with a Y-shaped osmeterium on the prothorax. They also emit a foul odour when disturbed. Larval period is 8-14 days in summer but can extend up to 30 days in winter. Pupation takes place on the plant. Pupa, which is called chrysalis, is 3 cm long, greenish to brown in colour, resembles a twisted leaf and remains attached to a branch with a fine silken thread. Pupal period is 8-15 days.
The pest completes 5-6 generations in a year and there is no hibernation. Total life cycle may take 100 days to complete depending on temperature. Peak population occurs in April and then July to October.
Distribution: The entire Indian subcontinent and SE Asia, China, Japan and Northern Australia.
Control: Handpicking and destruction of the larvae which are so prominent on the leaves helps to save the plants in nurseries. Dusting the trees with sodium fluosilicate or BHC 5% or spraying malathion, endosulfan, parathion, fentrothion 0.02% or lead arsenate 0.25% effectively controls the pests orchards.
Spraying spores of Bacillus thuringiensis gives high mortality of caterpillars.
The egg-parasites, Trichogramma evanescens, Petromalus luzonensis and Telenomus sp. destroy large number of eggs. The larval parasites, Erycia nymphalidaephaga, Charops sp. and Brachymeria sp.have also been recorded on this pest.