LEAF EATING CATERPILLAR

Classification

Distribution: India (Tamil Nadu, Kerala, Karnataka, Andhra Pradesh, Orrisa, Maharashtra,West Bengal and Gujarat), Sri Lanka, Bangladesh and Myanmar.

Main Host: Coconut

Alternate Host: palmyrah, tailpot palm, wild date, ornamental palm and banana

Occurrence: round the year with a spike in population during summer (March – May). Under favorable conditions the sporadic outbreaks lead to severe damage in coconut plantations.

Life Cycle:

Eggs are oval, creamy white, 0.6 to 0.7 mm long and 0.3 to 0.4 mm wide. The eggs are laid distally on the lower surface of the leaf let near the old gallery. The egg period is five days.

The larvae that hatch from the egg are cylindrical, slightly compressed with a tapering hind end. The larval period lasts for 42 days with eight instars including the pre pupal stage. The fully-grown larva is about 15 mm long, light green with reddish brown stripes. There are three longitudinal stripes that run dorsally, one median and two laterals. The head is brown to black and curved inwards.

Pupation occurs in the silken cocoon in the larval gallery. The pupa is light to dark brown, somewhat flattened dorsoventrally, anterior end blunt and posterior end tapering.

The adult emerges from the pupa after 12 days. Adult is a medium sized moth; female 10 – 15 mm long and 20 – 25 mm wide (Wing expanded); male slightly smaller in size. Head and thorax are light grayish ochreaceous in color; forewings elongated with finely scattered blackish scales; female abdomen stout and pointed at the tip. Abdomen in male is slender, ending in a short brush or scales and with a conspicuous tuft of hairs at the base of hind wing. The longevity is five days for females and seven days for males. The life cycle from egg to adult is completed in two months.

Damage:

The leaf eating caterpillar / black headed caterpillar causes severe damage to palms in coastal and backwater areas and in certain internal pockets of peninsular India.In severe outbreaks of leaf eating caterpillar, the older leaves of the palms are reduced to dead brown tissue and only three or four youngest leaves at the center of the crown remain green. In the year following the outbreak the crop may be reduced to half. The larvae are harbored in the lower surface of leaf lets in galleries made of excreta and silken web. It gregariously feeds on chlorophyll containing parenchymatous tissues reducing the photosynthetic efficiency considerably. In case of severe infestation, the whole plantations present a scorched appearance.

Management :

Cut and burn the heavily affected and dried outer most 2 – 3 leaves.

•  During sporadic outbreaks the pest can be kept under check by spraying dichlorvos 0.02% or malathion / phosalone each at 0.05%.

•  Biological method:

Release of parasitoids is to be fixed based on the target stage of the host present at the time of observation. Release is to be carried out at fortnightly intervals. Release bethylid, Goniozus nephantidis for third larval stage or above; Elasmid, Elasmus nephantidis for pre pupal stage and Chalcid, Brachymeria nosatoi for early pupal stage. Larval parasitoid, Bracon hebator and pupal parasitoid Xanthopimpla punctata can also be used as promising parasitoids. In a multistage condition of the pest, combined release of the parasitoids is required. When an insecticide treatment is given, the release of parasitoids is to be done only after three weeks of spraying.