–by Jeff Whitworth — Field Crops
Japanese beetles have been very active throughout Kansas for the last 2 months. However, they seem to have been more widespread north of Interstate 70 from the Missouri border west to about Smith Center. There were a few “hotspots” south of I-70 but not as widespread. Japanese beetles can be a concern in field crops because they can feed on green silks in corn or on leaf tissue in soybeans. They do have a wide host range but those are the two vulnerable crops and it is just a matter of timing as to which are attacked. If any corn in the vicinity of where the adult beetles emerge is silking, it seems that is highly attractive to the hungry beetles. However, if corn silks are starting to turn brown when the adults are foraging they seem to be attracted to new succulent soybean leaves (see pic 3). Japanese beetles seem to be slowly increasing in numbers and range. The larvae are white grubs and most commonly feed on roots in some area of undisturbed plants, i.e. turf, pastures vineyards, etc. After the larvae pupate, the adults emerge and fly to any nearby food source. This usually starts towards the end of June or in early July. They then feed voraciously for a few days before disbursing to start depositing eggs back in the “nursery” area. They continue this feeding-disbursing, etc. usually for about a month or so. Adults then die, eggs hatch, and the cycle starts all over again.
Picture 3: Japanese Beetle damage (pic provided by Jeff Hammer)