The Rice Leaf Folder or The Rice Leaf Roller (Cnaphalocrocis medinalis)

 

The Rice Leaf Folder or The Rice Leaf Roller (Cnaphalocrocis medinalis)

Scientific Name:

    Cnaphalocrocis medinalis (Linnaeus)

Others name:

    The Rice Leaf Roller

Order:

    Lepidoptera

Family:

    Pyralididae 

Distribution:

    India, Sri Lanka, China, Japan, Madagascar, New Guinea, Pakistan, Sabah, Somoa, Bangladesh, South-east Asia, Korea, Philippines, Indonesia. West Iran, Solomon Isles, and East Australia.

Host:

    This is a sporadic pest. Rice and grasses of various species.

    The caterpillars are greenish, very agile and measure 20-25 mm in length. The moths are golden or yellowish-brown and measure 8-10 mm in length and 16-20 mm in wing expanse. The wings have 2-3 wavy lines characterized by dark bands.

Life-cycle:

    The pest is active during the night and rests on the undersurface of the leaves during the day. They mate between dusk and midnight. Oviposition starts 1 to 2 nights after mating. The females lay oval, creamy-white eggs singly or in pairs on the leaves and leaf sheath. The incubation period is 3 to 4 days. The freshly hatched larva has a white translucent body and a light brown head. Soon it starts feeding, and the body turns green. The larval period lasts from 15-25 days. The larvae pupate in loosely woven strands of silk threads inside the leaf fold. During the active season, the pupal stage takes 6 to 8 days. The life-cycle occupies 25-35 days.

Damage:

    The freshly hatched caterpillars feed on the leaves of young plants without folding them. The older larvae fold the leaves longitudinally into tubular structure by fastening the margins with silken thread and feed on the green leaf tissues within these folds. Larval feeding results in white transparent streaks which run parallel to the midrib. Each leaf blade may contain several such streaks and under heavy infestation, each plant contains several folded leaves, affecting the general vigor of the plants and reducing their photosynthetic ability.

Control:

    Use 1.3% lindane dust @ 25 kg/ha or spray 625 ml fenitrothion 50 EC or 375 ml offenthion 85.5 EC or 1 kg of carbaryl 50 WP, in 250 liters of water/ha when the pest activity is maximum from August to October.