Osborne said, "There are several bugs out there and potato bugs are right at the top of the list that are very, very resistant to any chemical you want to put on them. Sevin, most (other) insecticides, they just shake it off and go on, especially if hard shelled and adult." Insects damage plants, then fungal diseases get in the holes to kill them.
In a small garden situation, the most effective way to get rid of insects, including Japanese beetles, is "hand picking and throwing them into a bucket with dishwashing detergent and water to kill them ... It's definitely more environmentally friendly."
"You do not want a Japanese beetle trap. It's an attraction for Japanese beetles."
"The thing about treating insects is timing. Don't put an insecticide on right before picking. Read the label."