Rothamsted Insect Survey,
The adult wingless form is 1.3 - 3.3mm long, and broadly spindle-shaped. It ranges from yellowish green to a dirty reddish brown. It has black antennae and two black tubes (siphunculi) at the rear end, which are a little longer than (1.1-1.6 times) the pale rather pointed tail (cauda). The winged form is 1.6 - 2.9mm long and similarly coloured, with distinct dark intersegmental markings on the upper surface of the abdomen.
Host plants/Life cycle
This species spends its entire year on cereals and grasses. Only a small proportion of the population overwinters as eggs on Gramineae, and these hatch in March. The majority of the population overwinters as mobile stages on wild grasses or winter cereals and can develop rapidly in warm springs. Colonies of wingless aphids develop on the flag and upper leaves of cereals, then move to emerging ears, especially on wheat. Winged forms usually fly in late May/June, and the resulting colonies rarely become numerous before late June. In continuing hot dry conditions, these colonies can increase quickly. Winged forms continue to be produced throughout the summer in response to increasing population density and declining food quality, moving to re-infest crops or other grasses. It is from these that a comparatively small autumn migration arises, which infests early sown winter cereals as well as wild grasses.
This species is a major pest on wheat, a moderate pest on barley and oats, and a minor pest on maize. It causes direct feeding damage through May, June and early July, from the flag leaf to dough ripe stages (GS37 - 85). When present on crops before the flowering stage, it reduces the number of grains in the ear. After flowering to the end of grain filling, it reduces directly the size of the grain. This species also has pest status in winter-sown cereals in September/October, and throughout mild winters up to GS31, as a virus vector of Barley yellow dwarf virus. It is more cold - hardy than R. padi, and thus more significant in the secondary spread of BYDV in winter cereals.
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