These dark-colored aphids generally feed near the tips of infested stems and have been reported from several Kansas alfalfa fields since 1999.
Damage is similar to that caused by the pea aphid, and thresholds are likely to be comparable. Our data on insecticide efficacy for cowpea aphid control in Kansas is limited.
Source of information
Pest photo source
Phil Sloderbeck, KSU Entomology