Attack of the Green June Beetles

Green June beetle on leaf
Green June beetle in my vegetable garden.

After a hard, summer rain, I headed out to my garden early to pick vegetables. By midsummer it was a bit of a jungle; and I had charged well into the tangle of tomato plants before I heard and saw hundreds of huge, green June beetles swarming and buzzing all around me!

My first response was to duck-and-cover; but I quickly realized that to the June beetles, I was nothing more than a party pooper – getting in the way of their frantic eating, mating, and egg laying.

About Green June Beetles

There are several different beetles which are referred to as “June bugs;” but green June beetles are the giant, greenish, iridescent ones that are nearly an inch long. June beetles lay their eggs in rich, sandy soil; and the adults often emerge after a hard rain to feed on fruit. As I looked from my garden over the adjoining pasture; I could see thousands of beetles flying low over the grass, looking for mates and good places to lay next year’s eggs.

Adult green June beetle
Adult green June beetle.
Adult green June beetles do most of their damage to ripe fruits – tomatoes, figs, berries, apples, peaches, plums, and even corn. A few June bugs flying around your yard is usually nothing to worry about, but they can be particularly problematic in orchards, where their feeding and waste can ruin a good fruit harvest.

For egg laying and grub activity, June beetles are drawn to rich soil; and they can become a pest of lawns, golf courses, and playing fields. June beetle larvae fall in the general category of “white grubs.” They’re distinctive not only because they’re huge (up to 2” long), but because June beetle larvae crawl on their backs with their feet in the air.

If your lawn has a white grub problem, you may find June beetle grubs among them, but they’re likely to be far outnumbered by other, more damaging grubs such as Japanese beetles. The larvae eat decaying organic matter, rather than plant roots, so their damage is mostly caused by tunneling and disturbing the soil under the grass.

If you only have a few beetles, the grubs can actually act as beneficial aerators of the soil. But if the infestation is severe, tunneling by white grubs can begin to cut off contact between the soil and grass roots. Like other white grubs, June beetle larvae are active in the fall and spring, while adults are active in mid to late summer.

Green June beetle on sunflower
Green June beetle on sunflower in my garden.

How to Control Beetles and Grubs

In my own garden, the June beetle air raid was over almost as quickly as it began, and I didn’t notice any damage to my vegetable crop. They congregated mostly on my sunflowers, which were nearly done for anyway. While I scared a few out of my tomato plants, they didn’t seem to be destroying them.

To check for green June beetle grubs, dig up flat sections of sod several inches deep. If you see upwards of 10 grubs per square foot, your lawn may be suffering. The best time to control adult beetles is in the summer when they’re most active. Beetle grubs should tackled during the early fall.

Here are some tips on how to control beetles in your lawn or garden:

  • Keep Lawn Healthy: Overseed bare spots to minimize the damage caused by grubs. In mild cases, this might be all you need to do to get beetles under control.
  • Till Garden: If grubs are taking over your compost-rich garden soil, try tilling in the fall and again in early spring. The birds will appreciate all those tasty grubs you unearth!
  • Nematode Control: Nematodes are microscopic parasites, and several kinds are known to attack white grubs. Be sure to choose a species rated for June beetle grubs, and follow the package instructions.
  • Natural Predators: A type of digger wasp, Scolia dubia, loves to parasitize June beetle grubs by laying eggs that hatch and feed on the grubs. Sometimes called the blue-winged wasp, these wasps are most active in early fall, usually flying around low to the ground in search of grubs. To encourage natural predators, like wasps, avoid the use of broad-spectrum chemical pesticides.
  • Chemical Control: If necessary, there are chemicals available that are applied in the fall to control green June beetle grubs. Also, during the adult flying season, pesticide soaked overripe fruit can be placed around the perimeter of orchards to help control adult beetles.

Further Information