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Extension Entomology

Month: June 2018

Alfalfa Update

Posted on by Sharon Schroll

— by Dr. Jeff Whitworth and Dr. Holly Davis

Several alfalfa fields were sampled in north central Kansas this past week.  The alfalfa canopy remains an excellent habitat for many insects, especially those fields not treated for alfalfa weevils this year.  Many of these insects are beneficial.

Very few pests, or potential pests, were detected although there were a few potato leafhoppers present.  These small, lime green, herky-jerky, moving pests are apparently just beginning to migrate into KS, as we didn’t find any earlier in the week, and now are only finding a couple of adults.  For more information relative to potato leafhopper management, please refer to the KSU 2018 Alfalfa Insect Management Guide:  https://www.bookstore.ksre.ksu.edu/pubs/mf809.pdf

 

 

 

Corn and Sorghum Update

Posted on by Sharon Schroll

— by Dr. Jeff Whitworth and Dr. Holly Davis

Chinch bug populations continue to increase at a very disconcerting rate.  Most corn throughout north central Kansas is far enough along in its development to tolerate large numbers of chinch bugs.  Smaller sorghum can still be seriously stressed by growing populations of chinch bugs, especially as the hot and dry conditions return.  For more information of chinch bug management in sorghum, please see the KSU 2018 Sorghum Insect Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/mf742.pdf

 

One relatively mature fall armyworm larva was also detected.  Thus, in approximately 2-3 weeks there will be a new generation of fall armyworm larva ready to start feeding, most likely, on sorghum.

 

Soybean Update

Posted on by Sharon Schroll

— by Dr. Jeff Whitworth and Dr. Holly Davis

The first adult Dectes stem borer was detected on 23 June, from north central Kansas (specifically, DK Co.).  These beetles traditionally spend approximately 7-14 days congregating or aggregating around the borders of stubble fields near where they overwintered.  Then, they disperse throughout soybean and sunflower fields and begin depositing eggs in plants of either crop.  Several more have been collected since the 23rd.

Bean leaf beetle adults have been and will continue chewing characteristic round or oblong holes in soybean leaves.  However, at least around north central Kansas, populations seem reduced from recent years.

 

So far, other than a few small grasshopper nymphs, there seem to be less defoliators than usual in either alfalfa or soybeans.  However, there is still time left for significant populations to develop.  A few garden webworms and yellowstriped armyworms were collected from a couple of fields and many of the soybeans are still very small, in the 3-5 trifoliate stage.

 

Grasshoppers

Posted on by Sharon Schroll

— by Dr. Jeff Whitworth and Dr. Holly Davis

 

Grasshoppers

Grasshoppers continue to feed and thus get larger.  As they feed and develop, they often move out of the grassy areas where they hatched and start feeding on a nearby crop.  Thus, the best time to control grasshoppers is before these nymphs move into crops, or at least while they are still just feeding on the crop borders.  Grasshopper baits work, but often do not compete well with green, succulent, growing crops.

Green June Beetles vs. Japanese Beetles

Posted on by Sharon Schroll

— by Dr. Jeff Whitworth and Dr. Holly Davis

Adults of both green June beetles and Japanese beetles seem to be ramping up their activity throughout eastern Kansas.  These two relatively large, conspicuous beetles are being confused.  Green June beetles, at 1 inch long, are considerably larger than Japanese beetles.  Also, green June beetles are green to copperish green in color and more pointed toward the anterior (head) end.  Japanese beetles are probably only 1/3 to ½ as big as the green June beetle.  They also have small, but highly visible, little white tufts of hair on both sides of the abdomen sticking out from under the elytra.

 

 

Japanese beetles may be found feeding on silks in corn fields and/or pollen or leaves in soybeans while green June beetles are more confined to feeding on nectar from flowering bushes or trees close to where the larval stage, i.e. grubs, were developing in the soil.  Green June beetles are not an agricultural concern while Japanese beetles occasionally can be.