Grain Aphids
From BugwoodWiki
Photo by Alton N. Sparks, Jr., University of Georgia, Bugwood.org
Photo by Merle Shepard, Gerald R.Carner, and P.A.C Ooi, Insects and their Natural Enemies Associated with Vegetables and Soybean in Southeast Asia, Bugwood.org
Photo by Frank Peairs, Colorado State University, Bugwood.org
Description
Several species of aphids are known to feed on and injure winter grains including bird cherry-oat aphid (Rhopalosiphum padi), English grain aphid (Sitobion avenae), corn leaf aphid (Rhopalosiphum maidis) and greenbug (Schizaphis graminum). Aphids are soft-bodied insects. Both the English grain aphid and the bird cherry-oat aphid have been identified to vector the disease, Barley Yellow Dwarf (BYD). The most prominent characteristic of aphids is the presence of cornicles located on the abdomen.
Hosts
Wheat, barley, oats, corn, winter grasses and some summer grains.
Damage
Grain aphids feed by piercing the plant and sucking out the plant juices. Aphids often congregate on new tissue and can be found deep within the plant near the growth whorl. Damaged plants will often curl, wilt, and may die during periods of weather extremes. Plants infested with BYD will appear stunted and yellowish-purple in color and are subject to environmental stress. Aphid feeding and disease damage can significantly reduce yields. The most significant yield reductions occur when aphid infections develop in the fall on winter grains.
Life Cycle
Grain aphids can overwinter extreme cold temperatures as eggs, late instar nymphs or adults. Overwintering progeny are all females that give birth to living young. This first spring progeny are all wingless females that also produce live progeny without mating. The summer generation is winged and may develop on corn, other grain or volunteer grasses. Winged male adults appear in the fall and mate with over-summered females. Each female aphid lays only about 8 eggs. It is believed as many as 17 generations may develop in a year.
Control
Treat for aphids in small grains when populations in seedings exceed 15 per row foot, or 2 per tiller in plants 6-10 inches in size. Treat for aphids in the boot to soft dough stage when populations exceed 25 per stem or flag leaf. Fall applications of at-planting insecticides are recommended for small grain plantings in areas where aphids and barley yellow dwarf are annual problems.
