Recently I noticed a large green beetle in a butterfly bush. It was a dull hunter green color with brown stripes. I’ve seen a few of them in the past but I didn’t know what they were. It didn’t take long to learn that these beetles are green June beetles (Cotinus nitida).
Green June beetles are common to the eastern US, especially in the south. While these insects haven’t received a lot of attention in the past here in PA, they have now been recognized as a turf pest in southeastern and southwestern Pennsylvania.
The adults are 3/4 -1″ long and have a velvety green to dull brown color with stripes of green with yellow-orange margins. The underside of the green June beetle is either a metallic gold or green. Adults also have a distinct flat horn on the head. The adults are active fliers and sound like a bumblebee as they move through the air.
While the adult can attack some fruits, the real problem of this insect is its larval stage. The female green June beetle lays eggs in turf in the summer and these eggs develop into grubs. The grubs feed on organic matter in the soil and the roots of grass. Active grubs will burrow to surface of the soil in the evening and often leave piles of accumulated soil on the lawn’s surface that look like earthworm castings. While the damage to a healthy lawn is minimal, stressed lawn may be damaged by the grubs feeding habits.
When the weather turns cool, the grubs burrow deeper into the ground and overwinter. They resume feeding in the spring and then pupate in the soil during May and June. After pupating, the grubs are transformed into adults which emerge from the ground to mate and start the cycle once again.
A well maintained lawn will be able to survive the damage of green June beetles. If the grubs are causing a problem, there are insect-parasitic nematodes that can be applied to control the grubs naturally. Also green June beetle grubs are parasitized by a type of digger wasp, Scolia dubia. This naturally occurring wasp can be seen flying above turf with a green June beetle infestation, seeking grubs in which to lay its eggs. There are also chemicals that can control severe infestations of green June beetle grubs. You can check with your county extension agent for recommendations.
I’ve never noticed mounds of soil on the grass from the green June beetle grubs. I also haven’t seen that many adults. It’s obvious that I don’t have a green June beetle problem. Maybe there are enough digger wasps in the area to keep this insect in check. What I do know is that I now can give a name to this beetle – the green June beetle.