Pest:Leaf Eating Caterpillars

This is a sporadic pest. Adult is a stout moth. The forewings are grayish brown with zigzag white lines on them. Hind wings are white (Fig 113). Eggs are laid on leaves in masses covered with brown hairs shed by the moth. Each egg mass contains numerous eggs. This hatch in 4-5 days. The young larvae feeds on tender leaves by scraping and later they feed on leaves causing holes. Larvae become full grown in 2-3 weeks. Full fed larva is

3.5-4 cm long. The body is greenish brown with dark markings and black ring encircling the body at both ends. It pupates in soil for one week.

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  • Pest 2
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Symptoms

  • These are smooth cater pillars(Image1). In the young stages, they can be seen in masses on the leaves scraping the green matter resulting in scarring on the leaves.
  • Grown up caterpillars hide in the leaf axils or at the plant base in soil or undersurface of dried leaves and bore the emerging leaf entering from the leaf axils. This results in occurrence of bore holes in a pattern as the leaf unfurls.(Image2)

Procedure for Observation

Select 5 plants at random from 10 cent plot .Assess the intensity of damage as:

Mild : Irregular holes ,< 10 % of the leaf area damaged

Moderate.10-20 %

Severe > 20%

ETL

10%.

Control Measures

  • Collect and destroy egg masses.
  • Cut and remove leaves containing young caterpillars which feed gregariously.
  • Remove half opened spindle leaves which are suspected to harbour the caterpillars during day time.
  • Stir the soil at the base of the plant to expose the pupae.
  • Spray hot chilli cow’s urine mixture diluted in water directing the spray inside the partially opened spindle leaf ,leaf axil and both the surfaces of leaves and at the base of the plant.( The mixture can be prepared by mixing one lit of cow’s urine in 10 lit of water and then adding 30 g well crushed green hot chilli. Filter and spray).
  • Spray quinalphos 25 EC @ 0.025 % (1 ml/lit water) . Direct the spray as suggested above.