One user claims:
"YES! They can surely bite! Today I was outside and felt a sting on my shoulder. Upon slapping it there was a Japanese beetle in my hand. I now have a large raised circle about the size of a quarter with two tiny teeth marks in the center of it. It's very itchy as well. They DO indeed bite."
But, Will Martin disagrees:
"Japanese beetles don't bite, but they are sticky and unpleasant if you touch one apparently! What they will do is eat your plants."
However, many more users believe the bugs DO bite:
"I see people here saying they don't bite. But I believe they do. I had one fly in my ear today and it got stuck. I had to be taken by ambulance to the hospital to get it out because the pain was so bad I was puking and couldn't drive. I swear that thing was biting me."
AND
"One got in my ear when I was asleep. I know the pain. I was screaming and crying at 3 a.m. I finally took the turkey baster and filled my ear with water to drown it. Finally, it fell out."