- The adult feeds on the green tissues of the leaves and feeding scars appears as short white lines on the leaf surface.
- The grubs mine the leaves causing white blotches on them. Such leaves finally dry up.
- Early stage of the crop is usually attacked. Infested areas are seen in patches and appear white in colour due to loss of chlorophyll.
Randomly mark 4 one meter sq. per 0.4 Ha. Observe five hills at random in a sq.m and count the total number of adults or damaged leaves and work out the average per hill.