Japanese beetles are an invasive species in North America.
A Japanese beetle (Popillia japonica) on a red clover (Trifolium pratense) flower. Picture taken in Scarborough, ON.
Japanese beetles were introduced to North America from their native Japan probably by accident with a plant shipment about a hundred years ago and they have been spreading ever since.
Japanese beetles are beautiful and highly photogenic, especially as they hang out on red clover flowers.
A different view of a Japanese beetle on a red clover flower.
Nevertheless Japanese beetles are considered pests because their larvae eat the roots of various grasses thereby destroying lawn and turf. One method of controlling them is to spread the bacterium Paenibacillus popilliae that causes the disease known as milky spore in the grubs of the Japanese beetle.
Further Readings:
Japanese beetle on Wikipedia.
Milky spore on Wikipedia.