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Extension Entomology

Tag: leaf feeding

Japanese Beetles

Posted on by Sharon Schroll

— by Dr. Jeff Whitworth and Dr. Holly Schwarting

Adult Japanese beetles have been detected around north central Kansas in the last 7-10 days.  These adults may feed on corn, sorghum, and soybean leaves, as far as field crops are concerned, and may cause some “window paneing” much like the leaf feeding of adult corn rootworms.  However, this leaf feeding usually is of little consequence.  In corn, these beetles will be attracted to the silks and, as they can be very veracious feeders, may clip these silks at a pretty good rate.  Fortunately, they are usually localized to small “hot spots” in some fields and thus do not really justify any insecticide application.  These adult Japanese beetles may be active for another couple of weeks, after which only eggs and larvae will be present, and these life stages are not a threat to these crops.

 

Alfalfa Update

Posted on by Sharon Schroll

— by Dr. Jeff Whitworth and Dr. Holly Schwarting

Alfalfa in north central Kansas doesn’t seem to be in the overwintering mode yet.  It is still growing, albeit slowly.  But, the unusual situation this warmer-than-average fall weather has caused is with alfalfa weevils.  On 16 November, several alfalfa fields were sampled in north central KS and many adult alfalfa weevils were captured.  However, the unique situation was the sampling of many alfalfa weevil larvae. Some leaf feeding by these larvae was also evident. These insects are normally univoltine (one generation of alfalfa weevils/year).  The adults are moving, or have moved, back into the alfalfa fields by now and started laying eggs.  Eggs laid in the fall are not normally developed enough to hatch this time of year.  Late February is usually the earliest that alfalfa weevil eggs hatch.  After the coming cold front moves through and temperatures warm back up we will re-sample to determine how the cold temperatures impacted these larvae.

aw-adult-nov

 

aw-larvae-nov

Also, there are many pea aphids present which is not as unusual for this time of year.  Numerous lady beetles are also present but they do not seem to be feeding on either pea aphids or alfalfa weevil larvae.

pea-aphids_aw-feeding

Sorghum Update

Posted on by Sharon Schroll

–by Jeff Whitworth and Holly Schwarting

Double cropped sorghum in north central KS seems to have a significant infestation of “ragworms”.  The larvae are a combination of fall armyworms and corn earworms and are of various sizes.

corn earworm_ragworm

windowpane ragwormfall armyworm_ragworm

 

Leaf feeding in the whorl by either species is highly visible but should not have a significant effect on the plants or yield.

windowpane ragworm

ragworm feeding

Also, most fields in north central KS are infested with aphids.  Corn leaf aphids can produce a great deal of honeydew but mostly in the whorls.  This honeydew may retard head extension but usually does not affect many plants over a large area.

corn leaf aphids

greenbugs

Yellow sugarcane aphids

Also found greenbugs and yellow sugarcane aphids.  None of the invasive sugarcane aphids were detected in north central Kansas.  However, many beneficials are, and will continue to be, present in sorghum fields as evidenced by the numerous green lacewing eggs and lady beetle eggs.

lacewing eggs