Aphids are some of the most common insects that infest wheat and cause economic loss. Species that typically cause damage sufficient to justify chemical control include Greenbug, Corn Leaf Aphid, Birdcherry-oat aphid, English grain aphid, and Russian wheat aphid. Several of the species are known to vector the virus that causes Barley Yellow Dwarf.

Although some individual aphids can overwinter in the northern climate, populations of most aphids found on small grains in South Dakota come from migrating aphids from the south with winds, sometimes at jet stream elevations. Rain events can wash them out into crop fields. Once established, they build populations rapidly and some of the population becomes winged, allowing them to disperse.

Cultural control involves planting spring wheat early and winter wheat later, both of which minimize the period of time the wheat plants are subject to infestation. Some species primarily colonize vegetative parts of the plant, others, such as the English grain aphid, often develop on leaves and move to the heads in the boot and heading stage.

Aphids are vulnerable to many species of insect parasites and predators such as lady beetles and damsel bugs, so consider the presence of these insects before making insecticide application decisions. For more information, visit the “Small Grains” page of the “High Plains Integrated Pest Management” website, scroll down to the “Insects” section and click on individual species of aphid, such as “Bird Cherry-oat Aphid”.