Soybean aphids can be found mainly on the young leaves and
stems of the soybean plants early in the season.  As the soybean
plants mature, the aphids tend to be found mainly underneath the
lower leaves and on the developing pods.

The presence of numerous ants and lady beetles in the soybean
field are signs that soybean aphids may also be present.  Ants
feed on the honeydew excreted by the aphids; lady beetles utilize
the aphids as food. 

Soybean leaves that look “sticky” or “sooty” are also signs of aphid
infestations.  This “look” is possibly due to the honeydew excreted
by the aphids as they continuously feed on the soybean sap. 

As with any insects, the distribution of soybean aphids in the field
will not be uniform, and there may be more aphids in the field
borders early in the season.  Thus, to estimate the average number
of aphids per plant, sample the field from the border to the middle.

Count soybean aphids from at least 10 plants at 10 representative
locations in the field (for a total of at least 100 plants inspected).
The entire plant must be examined because the aphids could be
in the stems, growing points, flowers, pods, or underneath the
leaves.
 

   |  SD Soybean Aphid Biology  |

Prepared and posted  by Mike Catangui on December 23, 2002.  Last updated on Friday May 2, 2003.