Damage to host plants results from the removal of large amounts of plant sap and the introduction/effect of feeding toxin. Scotinophora coarctata sucks the sap from the midrib of leaves and panicles at the milk stage, but in most cases they feed upon the basal part of the tillers mainly at night. Feeding causes desiccation in the plant, discoloration of the leaves, and death in the upper leaves, young leaves may fail to unfold. Plant growth is stunted and tillering is reduced.

During the vegetative stage, plants attacked by S. coarctata become stunted and the youngest leaf shoot of the tiller folds longitudinally, turns yellowish to reddish brown, and later dies (deadheart). Panicles may fail to emerge or are under developed and panicles with empty grains (whiteheads) may be seen after the booting stage. Rice black bug can mummified and die after application of microbial insecticide.