The insect is a japanese beetle.  They have been found eating over 40 different plants.  They deposit eggs in the soil and the larvae are grubs which feed on plant roots.  They emerge about this time of year as adults to reproduce and feed.  They can be controlled but it takes time and several applications of pesticides at the right time to the soil to kill the grubs.

There are parasites which you can introduce into the soil that will keep the numbers down but they also need to be applied under specific conditions to get them established.  Soil, temperature, moisture are all factors that need to be considered.

Look on line  to learn more about the biology an other control methods