Yellow Stem Borer

Adult female moths are pale yellowish-white, and each forewing typically bears a small dark spot. Egg masses are laid on leaves and covered with buff-coloured scales from the female. Larvae are pale and found inside the stem, so confirming their presence usually means splitting affected tillers lengthwise.

Deadheart

The dead, easily pulled central shoot of a vegetative-stage tiller caused by a larva feeding at its base.

Whitehead

An erect, empty, whitish panicle produced when a larva damages the stem at or after heading.

Moths lay egg masses on the leaves, and newly hatched larvae move to the stem and bore inside, where they feed and develop through several instars before pupating within the stem. In warm conditions the life cycle is completed in a few weeks, giving several overlapping generations across a rice-growing season.

Larvae can survive in rice stubble and volunteer plants between crops, so carry-over between seasons is an important part of the pest cycle in continuously cropped rice systems.

When larvae feed inside the stem of vegetative-stage plants, the central leaf whorl dries and can be pulled out easily, producing a deadheart. When damage occurs around or after panicle emergence, the panicle fails to fill and stands erect and whitish as a whitehead. Losses depend heavily on crop stage at attack and on the proportion of tillers affected.

Rice is the primary host. The relationship between the number of borers and actual yield loss varies with plant compensation, timing, and variety.

Monitoring combines counting deadhearts and whiteheads in the field with tracking adult moth activity, often using light traps or pheromone traps where available, and inspecting foliage for egg masses. These observations, judged against local economic thresholds, guide whether and when action is warranted.

Management uses cultural, biological, and monitoring-based tactics together within an integrated pest management framework.

• Use tolerant or less susceptible varieties and appropriate planting dates where recommended
• Practise field sanitation, including managing stubble and volunteer rice that carry larvae between crops
• Conserve egg and larval parasitoids and other natural enemies
• Avoid excessive nitrogen, which can favour borer build-up
• Base any intervention on scouting for egg masses and early symptoms against local thresholds