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Sci Tech
Managing bark caterpillar
Peculiar galleries, generally near the fork or angles of the stem and branches indicate incidence of the pest.
BARK BORER or bark catterpillar is a polyphagous and serious pest in South IndiaIt attacks mango, guava, citrus, moringa, orange, cashew, ber, jamun, litchi Emblica casuarina Acacia, Cassia, Thespesia, polyalthia, kapok, jack, pomegranate etc.
The adult is a stout brown moth with grey wavy markings on the wings. Eggs laid in crevices hatch in 7-10 days. The larva bores into the stem to about 15-25 cm. It feeds on bark under shelter of galleries or webs made by fragments of bark and excreta with silk.
Usually only one larva can be seen per bore hole. However, severely infested tree may have as many as 15-30 larvae. Full grown larva measures 3.5-3.8 cm in length and the larval period lasts for several months. The incidence of the pest is easily made out by the presence of peculiar galleries, generally near the fork or angles of the stem and branches. In extensive attack, the whole trunk may be covered with interlacing tracts destroying the outer layer of bark.
The larva pupates within the shelter tunnel. Pupa possesses rows of hooks on the abdomen by which it climbs to the top of tunnel to release the moth. Pupal period lasts for 2-3 weeks. Adult emerges leaving a portion of the empty pupal case protruding out of the tunnel. In infested trees, flow of sap is interfered with and the tree ceases to flush in cases of severe infestations.
Surveys conducted at National Pulses Research Centre, Vamban during 1996-1998 revealed that bark borer incidence was high during January _ March, moderate during April _ August and low or nil during September _ December. Fresh incidences were noticed during January and February months.
Taking control measures before extensive damage on bark is essential. Rubbing off the matted frass from the tunnels in the bark and spraying of insecticides such as monocrotophos 36 WSC 0.1 percent (3ml/lit) or quinalphos 25 EC 0.1 per cent (4ml/lit) on the infested portions control this pest.
Probing the shelter tunnel with a hooked wire and killing the larva is also effective in controlling the bark borer. Inserting cotton swabs soaked with 10ml of dichlorvos 76 EC into the tunnel and sealing it with mud kills the larvae effectively.
T. Senguttuvan
National Pulses Research Centre
Vamban Colony-622303
Pudukkottai
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