This time of year with the cold front coming through your area I would think Jap beetles could not survive. Mother nature may have taken care of your problem. We do not have Jap beetles in my area so I do not keep up on them. May be I am missing something here and you have jap beetle grubs?? Because of the cold weather the ground surface temp will drop and Grubs will go deep for the winter and be much harder if not impossible to control. This year mask chafer beetle grubs were active well into Dec and that is not a normal event. But this has not been a normal year weather wise. Each year a different disease or pest becomes more active in an area because of the ever changing environment.
"TG doesn't give a rats ass about being "Responsible" as long as sales/production quotas are met. That's it in a nutshell. A recipe for disaster IMO." Ted Putnam 2/28/14
You can lead a Donkey to water but you can't make the Jackass Drink
"As Americans you have the right to be stupid." John Kerry
"Life is tough, but it's tougher when you're stupid.” John Wayne.