The Green June Beetle, Cotinis nitida, is a common pest across the eastern United States, often recognized by its loud, buzzing flight pattern during the summer months. These insects damage ripe fruits and disturb turf areas. Effective management requires a targeted approach that considers the beetle’s unique life cycle and behavior. The following strategies provide actionable methods to reduce infestations, protecting your lawn and garden from both the adult beetles and their grubs.
Identifying the Green June Beetle and the Damage They Cause
The adult Green June Beetle measures about three-quarters of an inch to one inch long. Its dorsal side is a velvety, dull green, sometimes featuring lengthwise stripes, while the underside is a shinier, metallic green or gold. These beetles are clumsy fliers, and their distinct, loud buzz often alerts people to their presence in mid-summer.
Damage differs significantly between the adult and larval stages. Adult beetles primarily target ripe, soft fruits, such as peaches, figs, grapes, and berries, gouging large holes in the surface. The grubs, which are the larval stage, damage turf through burrowing activity rather than root feeding.
These creamy-white, C-shaped grubs grow up to two inches long and crawl on their backs when exposed. As they tunnel to the surface at night to feed on decaying organic matter, they create small, volcano-like mounds of loose soil, often two to three inches in diameter, which disfigures the lawn. This tunneling loosens the soil, causing grass to dry out and thin, which is the main form of turf injury.
Strategic Control Based on the Life Cycle
The Green June Beetle completes its life cycle in a single year, requiring control efforts to target the specific life stage at the right time. The beetle overwinters as a mature grub deep in the soil, feeding in the spring before pupating from May through June. Adult beetles emerge in mid-summer, typically around July, to mate and lay eggs.
Females lay clusters of 10 to 30 eggs in soil rich with organic matter, such as compost piles or heavily mulched areas. The eggs hatch in approximately two weeks, and the small grubs grow rapidly into the third instar stage by late summer or early fall. This late-summer period is the best time for grub control, as the grubs are newly hatched, actively feeding, and close to the soil surface.
The adult stage, active from mid-to-late summer, is targeted for fruit protection and reducing egg-laying. Treatments aimed at adults prevent fruit damage and minimize the number of eggs laid in the turf. Curative applications for grubs are best timed for late summer and early fall when they are most vulnerable.
Non-Chemical and Biological Methods for Control
Low-impact and biological methods can effectively manage Green June Beetles without relying on synthetic chemicals. For adults damaging fruit, physical removal is a straightforward technique. Adult beetles are active during the day and can be hand-picked or swept off plants early in the morning.
Exclusion is a reliable method for protecting valuable fruit crops. Placing fine mesh netting over fruit trees and berry bushes during the peak adult flight period prevents the beetles from accessing the ripe fruit. Trapping the adult beetles is another physical control, often using a simple, fermented bait—such as a mixture of overripe fruit or molasses and water—placed in a narrow-necked container.
For grub control, beneficial nematodes offer a biological solution. The species Heterorhabditis bacteriophora is recommended for targeting white grubs, including the Green June Beetle. These microscopic worms are applied to the soil, where they actively seek out and parasitize the grubs.
For best results, nematodes must be applied when grubs are small and active, typically from mid-August through September. The soil must be kept moist before and after application to allow the nematodes to move and survive. Naturally occurring predators, like the parasitic scoliid wasp, also help control grubs, but this biological control is usually not sufficient for a severe infestation. Avoiding the excessive use of manure-based fertilizers or large compost piles near turf can also reduce the area’s attractiveness for egg-laying.
Chemical Treatment Options and Prevention
Chemical treatments should be considered for severe infestations where non-chemical methods are insufficient, strictly following all label directions. For grub control, insecticides are categorized as either preventative or curative, based on application timing and active ingredients. Preventive insecticides, such as those containing neonicotinoids like imidacloprid or diamides, are applied in June or July to kill newly hatched grubs before damage occurs.
Curative insecticides, which contain active ingredients like carbaryl or trichlorfon, are applied later in the season, typically in late August or September, when grubs are larger but still feeding near the surface. When applying contact curative products like carbaryl, do not water them into the soil; the goal is for the grubs to encounter the insecticide when they crawl to the surface at night. Applying these products late in the day is advised because the nocturnal grubs will move to the treated surface in the evening.
For long-term prevention, reducing the amount of organic matter available for egg-laying is a practical step. Since females prefer moist soil rich in decaying materials, removing compost piles or heavily mulched areas near turf reduces infestation sites. Maintaining a healthy lawn through proper watering and mowing helps the turf tolerate some grub activity, masking minor damage. Limiting thatch buildup through regular dethatching also makes the area less appealing for egg-laying adults.