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Rice bug (Leptocorisa oratorius and related species) feeds by sucking the milky content out of developing grains. Damaged grains become empty, discolored, and often develop dark spots at the feeding point. The insect emits a strong distinctive odor easily noticed in an infested field.

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When rice is most vulnerable

Heading through milk stage. Once grains have hardened past the dough stage, further feeding causes little damage.

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How rice bug shows in satellite data

  • No reliable satellite signature - grain damage does not show as canopy change.
  • Yield-map or reports data show quality reductions (increased empty and stained grains) despite normal NDVI.
  • Weather and phenology are the main triggers for scouting alerts, not imagery.
Rice bug is a grain-quality problem. It will not appear on your NDVI dashboard. Schedule scouting at heading, especially if your field borders grasslands or fallow.

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Field symptoms

  • Empty, shriveled grains with dark spots at the feeding site
  • Discolored, off-color panicles at milk stage
  • Bugs visible on panicles in early morning and late afternoon
  • Strong distinctive odor (“bug smell”) on entering the field
  • Yield loss quantified only at threshing

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Reduce the damage by

  • Keep bunds and surrounding grasslands clean - rice bug breeds in wild grasses and moves into rice at heading.
  • Synchronized planting across an area reduces the window during which flowering rice is available to the bugs.
  • Early morning hand-net catching works on small plots.
  • Selective insecticide (a single spray of a pyrethroid or neonicotinoid) at heading only if scouting shows more than one bug per hill.
  • Do not spray after milk stage - most damage is already done.

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Set an alert for early warning

Turn the diagnosis into a trigger. Use a phenology-based reminder rather than an imagery alert.
Recommended settings for rice bug on rice:
  • Calendar reminder - schedule scouting at heading, especially on fields bordering grasslands or fallow.
  • New Imagery alert during heading to prompt a scout visit even though the insect does not show in the NDVI itself.