Kansas State University


Extension Entomology

Tag: boot stage

Sorghum Pests

–by Dr. Jeff Whitworth, Dr. Holly Schwarting and J.R. Ewing

Sorghum fields checked in north central Kansas this week indicated a variety of very active pests.  Fields were anywhere from whorl-stage to flowering.  Regardless of the stage of plant development, 100% of the plants sampled were infested with chinch bugs.  Most are still small reddish to brown or black nymphs, but there are still mating adults as well.  These bugs are feeding mainly around the base of the plants.

Chinch bug nymps many stages



Some plants in the boot stage have populations of corn leaf aphids feeding right at the top of the about-to-emerge heads.  Occasionally, these aphids are so numerous at the point of head extension that their honeydew interferes with the head’s emergence.  Fortunately, aphid populations were not found frequently enough to potentially impact yield, just an occasional plant here and there.

CLA on sorghum


Most of the whorl-stage sorghum (90%) is infested with a “ragworm”.  These are a combination of corn earworms, armyworms, and fall armyworms, Mr. Tom Maxwell, Extension Agent in Saline County, even found a cattail caterpillar.  They are in all larval stages, but mainly smaller, from 1st to 3rd instars.  Thus, they will be feeding in the whorls for another 10-21 days, and then will pupate in the soil.  In approximately 7-10 days, moths will emerge and start ovipositing in sorghum, which is vulnerable from flowering to soft dough, and/or soybeans.  Some early flowering plants already had “headworms” feeding in the just emerging heads.

Ragworm feeding sorghum


Sorghum headworm


Chinch Bugs

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Chinch bug populations are increasing dramatically in north central Kansas.  Sampling plants from the boot stage to flowering revealed approximately 25-60 chinch bugs of all stages per plant (see photo).  Growing conditions have been good so far in central KS, thus plants have grown well and chinch bug feeding around the base of the plants (see photo) has not caused any concern, yet.  However, with these chinch bug populations still increasing (we are even still finding mating adults!) if growing conditions become less favorable,  the added stress caused by all these chinch bugs feeding around the base of these plants may substantially weaken the stalks and cause lodging prior to harvest.

chinch bug immatures2


chinch bug feeding


chinch bug mating