Green June Beetles

Tim Gibb, Insect Diagnostician, Department of Entomology, Purdue University

We are receiving many calls right now reporting very large, possibly mutated, King Kong size Japanese beetles emerging from yards and gardens.  Rest assured that these beetles are NOT mutated Japanese beetles nor have they come to take over planet Earth.  These are called green June beetles and while both these and Japanese beetles belong to the same family (scarabs) and have some similarities, the photo below shows major differences in size, shape and coloration.

In addition to size differences it is important to know that the grub stages of the green June beetle prefer to live in very highly organic soils.  We have commonly found them in crops where animal manure is used for fertilizer and also in compost heaps in yards or near gardens.  Grubs are much larger than the Japanese beetles and have a very unique behavior of crawling on their backs.

Damage done by green June beetles pales in comparison to Japanese beetle damage. Grubs seldom cause observable damage either in lawns of gardens in our area.  When the adults beetles first emerge from the ground they may leave holes about the diameter of a dime in the soil.  Even in well manicured lawns, this is not considered problematic.

The beetles are sometimes attracted to and feed on ripe or decaying fruits and vegetables, but otherwise are not considered serious pest around homes and gardens.  These are mostly only a curiosity or a minor nuisance pest when they buzz around people.  Seldom is a chemical control justified. 

Green June beetles have only one generation per year so after late summer or early fall they will be beamed back up to wherever space ship they invaded from.

Click image to enlarge

Japanese beetle (right) and green June beetles (left)

Image courtesy of John Obermeyer