Like other aphids, Schizaphis graminum ingests phloem sap with its piercing-sucking mouthparts. This weakens the plant due to loss of nutrients and water. The necrotic lesions this causes appear as small yellow or reddish spots around the punctures. As feeding continues, these soon coalesce into larger patches. Eventually, the whole leaf will wilt and the plant may be killed off completely. The aphids prefer to settle on the undersides of older, lower leaves, which their colonies may cover completely in severe cases. On expanding, the colonies gradually move upwards on the plant. In the field as circular patches appear that slowly grow in size. S. graminum is an important vector of many crops.
Cheilomenes sexmaculata, Coelophora biplagiata, Harmonia dimidiata, Aphidius colemani, Diaeretiella rapae, Lipolexis gracilis, spiders, fungal pathogens, etc.