Kansas State University


Extension Entomology

ALFALFA—Pea Aphids, Lady Beetles, Syrphid Fly

–by Dr. Jeff Whitworth


Pea aphids are still quite active throughout north central Kansas. However, most populations have been considerably diminished for several reasons, but now are mainly just a food source for various beneficial insects (fig, 1) as seen here, two species of lady beetles actively feeding on pea aphids, and (fig. 2) a syrphid fly larva that was also actively feeding on pea aphids.


Figure 1 Lady Beetle feeding on pea aphid  — (Cody Wyckoff)

Figure 2 Syrphid fly larva feeding on pea aphid (Cody Wyckoff)

Pea aphids are usually considered a pest when populations approach or exceed a treatment threshold, they can also be useful as a food source for beneficials until other aphid species increase, if they do, in other crops. Even though these aphids are still plentiful in most north central Kansas alfalfa fields, there was NONE that came anywhere close to a treatment threshold. Also, a very few alfalfa weevil larvae (fig. 3) can also be found, this is not unusual, or a cause for concern.

Figure 3 Alfalfa weevil larva (Cody Wyckoff)


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