This pest causes the most damage during milking stage, that is the filling of the grains. Immature and adult rice bugs both feed on rice grains. Rice bugs suck out the contents of developing grains from pre-flowering spikelets to soft dough (endosperm) stage, therefore causing unfilled or empty grains, discoloration and erect panicles. Depending on the growth stage of the rice grain, the feeding can result in empty grains or small, shriveled, deformed grains with a spotty discoloration, sometimes with an offensive smell.
Rice bugs occurs sporadically during milking to grain filling stage only and emanate foul smell in the evening hours. They are actually found in all rice environments. Woodlands, extensive weedy areas near rice fields, wild grasses near canals, and staggered rice planting favors high population densities. More active when monsoonal rains begin. Warm weather, overcast skies, and frequent drizzles favor its population build-up. They are less active during the dry season.
Spray aromatic (like lemongrass) soap solution to expel the rice bug. Use “prahok” (local ‘cheese’ in Cambodia) near the field to attract the rice bug and kill it. Use a mosquito net in the early morning or late afternoon to remove the rice bug, crush it and put it in water then spray it to expel other rice bugs. Encourage biological control agents: some wasps, grasshoppers and spiders attack rice bugs or rice bug eggs. Indiscriminate insecticide use disrupts biological control, resulting in pest resurgence.
Always consider an integrated approach with preventive measures together with biological treatments if available. Use insecticides such as abamectin or chlorpyriphos in the evening hours by starting from the field edges to the center in a circular manner. This brings the bugs to the center and allows to manage them effectively. The benefits of using an insecticide must be weighed against the risks to health and the environment.
Begin scouting the field daily at pre-flowering.,Remove other host plants such as crabgrass, goosegrass and beans.,Preserve beneficial insects by spraying less insecticide.,Applications of fertilizer and water encourage rice to grow and develop.,Synchronous planting also helps to reduce rice bug problems.