Identification, symptoms and nature of

damage of Stem Borer and Gall Midge

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Rice is the staple food crop of humid

and sub-humid Asia, cultivated in 112

countries covering every continent and

is consumed by 2500 million people in

the developing countries.

In India, rice is grown on about an area

of 44.3 million hectares with a

production of 89.09 million tonnes.

However, rice productivity in India is

inferior to neighbouring countries.Healthy crop of rice

Introduction

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Stem borer damaged crop

The introduction of fertilizer responsive high

yielding varieties of rice following green

revolution, has increased the problems of

pests and diseases manifold and the

continuous use of pesticides led to the

outbreak of secondary pests.

Yield loss due to insect pests in rice has

been estimated to be around 25%.

Crop productivity can be enhanced by

effective management of insect pests.

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Courtesy: www. knowledgebank.irri.org

1. Yellow stem borer (Scirpophaga incertulas)

Identification

The stem borers are regular pests of rice

causing damage during both vegetative

and reproductive crop stages. Among five

stem borer species distributed in India,

yellow stem borer, Scirpophaga incertulas

is the dominant and widely distributed.

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Yellow stem borer female

Courtesy: www. knowledgebank.irri.org

Female moth has yellowish forewings

with a single dark spot at their centre while

the male has numerous small brown

spots.

A female lays eggs in batches of 50-80 at

leaf tips and eggs are covered with yellow

brown hair of female tuft. Therefore,

removal of seedling tips before

transplanting helps in reducing stem borer

incidence in field.

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Stem borer larva

Stem borer pupa

Life cycle of yellow stem borer Courtesy: www. knowledgebank.irri.org

Courtesy: www. knowledgebank.irri.org

The fully grown larva is pale yellow in

colour with orange yellow head. It passes

winter in rice stubbles and destruction of

rice stubbles also thus helps in reducing

incidence of this pest.

Stem borer completes its life cycle in 40-

45 days.

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Stem borer damage (white-ears)

Nature of Damage

Only larva causes damage to the crop.

After hatching, larva bores in to stem and

damages it

Damage during vegetative stage results

in drying of central shoot, damage

symptom called “dead heart”.

Damage after flowering results in white

empty straight panicles known as “white-

ears”.

As dead-hearts and white-ears harbor

larvae, their collection and disposal helps

in reducing incidence of this pest.

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Economic threshold level (ETL): 5% dead

hearts, 2% white ears or 1 egg mass/m2 or 1

moth/m2

Female sex pheromone (Scirpolure) traps are

used for monitoring and mass trapping of this

pest. Likewise light traps can also be utilized for

monitoring purpose.

Pheromone trap

Pheromone trapsLight trap

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Courtesy: www.cbit.uq.edu.au

Gall midge adult

Life cycle of rice gall midge

Courtesy: www. knowledgebank.irri.org

Gall Midge, Orseolia oryzae

Identification

The adult fly is a small mosquito like insect

with long legs. The female has bright

yellow abdomen whereas the male is dark

in colour. The female lays reddish

elongated eggs on leaf blade or sheath.

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Damage

This insect infests the crop from seedling stage

in nursery to maximum tillering stage. It does

not occur in north India but causes serious

damage in eastern, southern and central India.

Maggots (larvae) after hatching enter the leaf

sheath and convert it in to galls (tubular

structures) resembling shining onion leaf.

These symptoms are thus called “silver shoot”.

Early incidence of this pest results in to profuse

tillering and stunting. Removal of silver shoots

helps in reducing damage of this pest.

Economic threshold level (ETL)

1 gall/m2 or 5% infested tillers

Rice gall midge damage (silver shoot)

www.africarice.org

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Let us sum up

Stem borer is regular pest of rice causing damage during both vegetative and reproductive crop stages.

Only larva of stem borer causes damage to the crop. Damage during vegetative stage results in drying of central shoot called “dead heart”. Damage after flowering results in white empty straight panicles known as “white-ears”.

Female sex pheromone (Scirpolure) traps are used for monitoring and mass trapping of this pest.

Gall midge adult is small mosquito like insect with long legs. This pest does not occur in north India.

Gall midge infests the crop from seedling stage in nursery to maximum tillering stage.

Maggots (larvae) after hatching enter the leaf sheath and convert it in to galls (tubular structures) resembling shining onion leaf. These symptoms are thus called “silver shoot”.

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