In a paddy field some tillers show round onion leaf like silvery shoot in place of normal ear head. This abnormality is caused by

In a paddy field, some tillers show round onion leaf-like silvery shoots in place of a normal ear head. This abnormality is caused by Gall midge.
Rice gall midge is a pest of paddy crop, causing a tubular gall at the base of tillers, causing elongation of leaf sheaths called onion leaf or silver shoot. The population density of the rice gall midge is favoured mainly by cloudy or rainy weather.
It causes formation of a tube-like gall that is similar to an "onion leaf" or "Silver-shoot". Infested tillers produce no panicles.