Japanese Beetles will emerge from the larva stage in early June, eat your lovely flowers and shrubs and mate until late July. Their adult life span is only about six weeks long, during which time the female will continually lay eggs. These eggs will hatch around August into the larva or grub stage and it is then they do the most damage to your lawn. They are eating voraciously to develop enough food storage to over-winter deeper below the surface of the soil. This is also the time when your lawn can be most stressed from the heat and drought of summer. The appearance of large brown spots, a large number of birds feeding on the lawn, or moles burrowing in your yard could be a good indicator of their presence. By September the grubs will be finishing feeding and will move deeper into the soil for the winter months and not appear again until about mid-April. Therefore any chemical treatment is only effective during the times that the grub is feeding, and is best applied in the fall feeding cycle; treating any other time is a waste. A non-chemical means of control includes the use of a bacterial disease called Milky Spore and it infects the blood of the grubs. This process is slower, but it is not harmful to people, other insects or animals.