Since the so-called blue alfalfa aphid, Acyrthosiphon kondoi Shinji, was first identified in Oklahoma during 1977, extensive sampling programs have been conducted to determine the geographical and seasonal incidence of this species in relation to other aphid pests of alfalfa in the state. This aphid has now been found in 62 counties. Like the pea aphid, A. pisum (Harris), A. kondoi is a cool-season species which has been found primarily from April through June. Stunting of alfalfa due to A. kondoi infestations was observed in a total of 10 counties of central Oklahoma in March and April of 1980 and 1981. Because these infestations were confined to limited areas, the potential for more widespread outbreaks of this species has not yet been determined. From midsummer through fall, the spotted alfalfa aphid, Therioaphis maculata (Buckton), was often the only aphid species collected. The most severe aphid outbreak in the 5 years of this study resulted from survival of large numbers of spotted alfalfa aphids through the unusually warm, dry winterof 1980–1981. This species was associated with yield reductions and loss of stands throughout Oklahoma in the spring of 1981.
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Berberet et al. (1983) studied this question.