Insect Pests of Fruit, Plantation, Medicinal & Aromatic Crops (2+1)

1. Black headed caterpillar

1. Black headed caterpillar - Opisina arenosella Walker. (Cryptophagidae: Lepidoptera)

Damage

• The larva infests the under surface of leaves and it construct small galleries with silk frass and excreta and remain inside throughout. It feeds on the green parenchymatous tissues of leaflets from under surface leaving a thin parchment like upper epidermis undamaged. The infested leaflets slowly turn grey to brown and dry up in patches along the area where the each larva has been feeding. When a large number of leaves are affected the crown presents a scorched appearance from a distance. The damage by the caterpillar is severe during summer months.



Affected trees


Galleries of silk and frassy materials on the underside of leaflets


Bionomics

• The adult moth is small and greyish white. It lays eggs near the tip of the leaflets of the older leaves. The eggs are very small and hatch out in five days. The fecundity of the insect is 60-250 eggs /female. The newly hatched out larva construct silken tunnel or galleries. On the under surface of leaves where they live and feed. The larva is light green with a dark brown head measures 15 mm in length. The larval period is about 45 days. It pupates inside the galleries for 12 days. The total life cycle is completed in about two months.



Management

• Remove and burn all the affected leaves and leaf lets.
• Release larval parasitoids (Bethylids, Braconids and Ichneumonids) and pupal parasitoids (Eulopid) and predators periodically from January to check the build up of pest during summer.





• Release bethylid, Gbniozus nephantitis @ 3,000 per ha under the coconut trees when the pest is in the 2nd or 3rd instar larval stage. The optimum level of release is 1:8 host parasite ratio. Do not release the parasite in the crown region since they will be killed by spiders and reduvid bugs.
• Spray malathion 50EC 0.05% to cover the under surface of leaves thoroughly in case of severe epidemic out break of the pest in young plants.
• Harvest all mature nuts, and drill a downward slanting hole and inject 5.0 ml of monocrotophos 36 WSC into the stem at about 1.5 M above the ground level and plug with clay mixed copper oxy chloride.
• Inject monocrotophos based on age less than 10 years 5ml and above 10 years 10ml with equal quantity of water (5 ml) mixed in 20 ml of water into the stem. Plucking tender coconuts or harvesting the nuts should be strictly avoided for 45 days after treatment.
• Adopt the root feeding of monocrotophos for the control of black headed caterpillar.
• Select a fresh and live root, cut sharply at an angle and insert the root in the insecticidal solution containing monocrotophos 36 WSC 10 ml + water 10 ml in a 7x10 cm polythene bag. Secure the bag tightly to the root with a cotton thread. Twenty-four hours later check whether there is any absorption. If there is no absorption selects another root and redoes the procedure. Follow the precaution for the insecticidal treatment.