Beetles can destroy plants. Some species are more dangerous than others, such as Japanese beetles that feed on the leaves of a plant and lay their larvae in the soil, which then feed off of the roots. In order to kill beetles, you need to destroy both the larvae and the adult beetles. This can be done using milky disease spore and chemical control.
Treat the soil with milky disease spores
Treat the affected area, such as the garden or the lawn, with milky disease spores. These spores contain a bacteria that are deadly to the grubs. The grubs eat the spores, which then germinate and reproduce the bacteria and kill the grubs. The bacteria reproduce in the soil and prevent infestations.
Use physical control
Kill the adult beetles when you spot them to keep them from reproducing and to control the beetle population. In the morning, shake the beetles into a bucket of soapy water to kill them.
Apply chemical pesticides to kill the remaining beetles. Spray the foliage of the plants that the beetles like to eat, such as roses, grapes, maple, plums and lindens. Consult a professional for information on the best pesticide to use.