Vinegar sprays can kill Japanese beetles, but they also kill your plants. We don't recommend using vinegar directly on your plants, and you would have to spray it directly on the leaves for effective Japanese beetle control.  Even horticultural vinegar isn't safe to use on your plants. Horticultural vinegar has a higher acetic acid content than household vinegar, which means it's even better at drying out plants and killing them. This product is intended to kill weeds, not to use on plants for pest control.