- As a result of feeding by the larva (maggot) an oval chamber is formed around the maggot.
- Gradually this chamber grows out as an elongated cylindrical gall called the “Silver Shoot” because of its light shiny appearance.
- The gall is small and is not seen out side during the larval stage of the insect. Elongation of the gall takes place during pre pupal and pupal stage.
- Nursery to late tillering phase of the crop is subjected to infestation. The midge infestation in the early stage of the crop induces subsidiary tillering and they are also infested.
- Monsoon crop suffers more due to infestation by the gall midge, may be due to high rain fall and low maximum temperature. In general maximum infestation by the pest occurs on crop planted during June.
- Weeds such as Ischaemum aristatum Cynodon dactylon, Echinochloa spp. and Isachene spp are heavily infested by the insect when susceptible stages of rice are not available in the field.
Randomly mark 4 one square meter plots in 0.4 Ha. Assess the damaged tillers (silver shoots ) and total number of tillers and calculate the % damage.