The soybean aphid has syringe-like mouthparts and sucks out the sap
of soybeans.  Plant injury may be more subtle and harder to detect than
injuries caused by insects with chewing mouthparts, such as grasshoppers
and bean leaf beetles.

Soybean aphids may be small but when they multiply in large numbers
during the season, their collective feeding can potentially cause severe
damage on soybeans.

Soybean aphids waggle rhythmically while feeding.  I suppose we can
call it the "soybean aphid waggle."  Click here to view a video that I took
that shows the waggle.  I have no idea why they do this stuff.  It may be
related to sap flow.            

Sap feeding can cause yellowing, cupping, and wilting of soybean leaves.
Plant growth may also be stunted.  Leaf yellowing can be confused with
symptoms of potassium or iron deficiencies in the soil where the soybeans
were planted. 

Soybean aphids are capable of transmitting mosaic viruses that can cause
soybean diseases, such as soybean mosaic virus, bean yellow mosaic virus,
and alfalfa mosaic virus.  Although able to spread these diseases, however,
the soybean aphid currently has not been implicated in transmitting disease-
causing viruses in the U.S. 

During the 2002 growing season, SDSU research near Beresford indicated
that soybean fields sprayed for the soybean aphid had yield advantages
of between 2 and 11 bushels per acre, or 9-42% over unsprayed soybeans.

Insecticide Performances (2002) :  Yield     Aphid Numbers 

   |  SD Soybean Aphid Biology  |

Prepared and posted  by Mike Catangui on December 23, 2002.  Last updated on Friday December 16, 2005.