Kansas State University


Extension Entomology

Tag: yield

Bean Leaf Beetles in Soybeans

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Soybeans seem to be growing really well around north central Kansas.  As these plants start germinating and growing, however, they provide very attractive hosts for bean leaf beetles.


These soybean pests have been inhabiting alfalfa fields and grassy areas since last fall, waiting for these first soybeans.  They are very efficient at finding young, succulent soybeans when the plants start emerging.  They are also relatively unique as foliage feeders because they usually chew round and/or oblong holes in the leaves.

These beetles can eat an alarming number of holes in these small plants.  However, the young plants are very resilient at overcoming this leaf feeding and so there is normally very little impact on yield.  For more information on bean leaf beetle biology, treatment thresholds, and management options please see the following:

Bean Leaf Beetles: https://www.bookstore.ksre.ksu.edu/pubs/MF2824.pdf

Soybean Insect Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/MF743.pdf



Sorghum Pests

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Whorl stage feeding

Much of the sorghum in north central and south central Kansas will soon be, or is already at, the whorl stage.  That usually causes much concern if there are larvae feeding in the whorls, resulting in many “ragged” looking plants (see pic).  However, please remember that these worms cause highly visible defoliation but that does not translate into later problems with plant growth and development, or yield.  The larvae sampled this week in pre-whorl stage sorghum are mostly corn earworms (80%) with a few fall armyworms (20%) and were about half grown, so this feeding will continue for another 5-10 days.  This is of interest because the adult corn earworm moths, when they begin ovipositing in approximately 2-3 weeks, will probably do so in soybeans where pod feeding by the larvae can have a direct effect on yield.






















sorghum whorl feeding



corn earworm_sorghum



Fall armyworm_sorghum