Milky spore bacteria is a natural remedy for japanese beetles. It is typically applied in late summer, as a powder that is put down every four feet. It can take two or three years for an application of milky spore to fully take effect. It is supposed to be safe for humans, pets, and other insects, including butterflies. It only kills grubs. We see japanese beetles every summer, in our raspberry canes, and on the blueberry shrubs. I use a solution of warm water and detergent, in a white plastic cup, to trap and kill them. It is fairly easy to hold the open cup under the leaf, and flick the beetle into the water. They only live a few seconds, they cannot tolerate the soapy solution.