This has been a strange summer so far with above normal temperatures and threatening summer storms with wind, lightning, and heavy rain. When it does rain, it is all or nothing. This should not be a real surprise as winter and spring was unusual as well.

To add to the unusual, is the arrival of the Green June Beetles (Cotinis nitida), arriving in July. What is so unusual besides the July arrival, is we normally do not deal with this insect. The third unusual thing is that the beetles have been seen commonly cruising distinct patches of grass behaving almost like their flight patterns are confined by an invisible beetle fence.

The large, metallic green beetles make an audible “buzzing” sound like a bumble bee, as they follow a low-level flight plan cruising at about 2-3 feet above the ground punctuated by occasional dips and erratic turns.

These Green June Beetles are appearing in large numbers to terrorize gardeners, golfers, sunbathers, small children and pets as they buzz lawns and golf courses.

Raymond Cloyd, Kansas State University extension entomology, said that the male beetles swarm in the morning, “dive bombing” to and fro above the turfgrass searching for females that are in the turfgrass, desperately seeking a mate. Females emit a pheromone that attracts the males.

Eventually, clusters of beetles will be present on the surface of the soil or turfgrass with several males attempting to mate with a single female. Mated females that have survived the experience lay a cluster of 10 to 30 eggs into moist soil that contains an abundance of organic matter.

Joe Boggs, Ohio State University Extension educator in Hamilton County, also noted birds are not going to ignore the large gathering of the potential beetle meal deal. A study published in 2016 showed green June beetles commonly drew the attention of blue jays (Cyanocitta cristata) and common grackles (Quiscalus quiscala) with the jays appearing to selectively feast upon the female beetles.

The remaining female beetles seek turfgrass with high levels of organic matter (e.g. thatch) in which to lay eggs. It has been speculated that this attraction to decomposing organic matter explains why large numbers of adults will cruise above certain lawns while ignoring neighboring lawns. The same is true with golf courses with the beetles focusing on certain areas.

Eggs hatch in about two weeks in early August, and the young larvae feed near the soil surface. The larvae feed primarily on organic matter including thatch and grass-clippings, preferring soils that are moist.

Green June beetle grubs are one of the largest and strangest white grubs you’ll ever see in Ohio. The mature grubs are huge, measuring well over 1” in length. They look like white grubs on steroids. Unlike other beetle larvae found in turfgrass, green June beetle grubs burrow 10 – 12” vertically into the soil, and they remain closely associated with these burrows. Much of their damage to turfgrass is associated with their burrowing and tunneling behavior given that they primarily feed on decaying organic matter. However, they have been known to feed on turfgrass producing damage that appears as irregular patches.

The grubs venture out of their burrows in the late evening or during the night to feed or to go on an upside-down crawl-about in search of more food. They may also be driven out by heavy rains to appear in large numbers meandering across driveways and sidewalks or dropping into swimming pools. Besides the disgusting behavior of dropping into swimming pools, their large size seldom causes injury to turf grass equal to that caused by Japanese beetles or masked chafers.

Back to the unusual weather conditions. Excessive rain, heat, and wintertime conditions may have contributed to the buildup of organic matter and thatch in lawns. Control efforts should focus on reducing organic matter, particularly thatch. Thatch reduction using core aeration enhances aerobic decomposition of the organic matter by our amazing bacteria, which eventually make infested lawns less attractive to the buzz-bombing June Green Beetles.

Applying the active ingredient Carbaryl to lawns in mid-August will help to control the grub population. Adult beetles may be controlled by applying a synthetic pyrethroid product such as Bifenthrin.

Applications of organic matter to turfgrass should also be considered with caution. Anecdotal reports from turfgrass managers and others have pointed to a link between applications of garden compost and/ or the addition of organic fertilizers to the lawn increases the likelihood of the buzz-bombing beetles the following year.