The Green June Beetle (Cotinis nitida) is a large, brightly colored insect commonly seen buzzing around gardens during the summer. Its size, loud flight, and tendency to appear suddenly often lead homeowners to suspect it is an invasive species threatening local ecosystems. Understanding this insect requires separating fact from common misconception regarding its geographic origins and the specific nature of the damage it causes.
Status: Native Species or Foreign Threat
The Green June Beetle is not an invasive species; it is native to North America, widely distributed across the eastern and central United States, from New Brunswick to Florida and westward into states like Texas and Kansas. This scarab beetle has been part of the local fauna for centuries. The perception of it as an invasive threat often stems from its conspicuous appearance and its occasional status as a localized nuisance pest.
While the Green June Beetle can be a pest, it is a native organism whose population occasionally spikes. This distinction is important because management strategies for native pests differ significantly from those used to combat foreign invaders. The beetle’s established presence means it has natural predators and controls within the ecosystem.
Distinguishing Features and Behavior
Adult Green June Beetles measure three-quarters of an inch to a full inch long and possess a distinct, velvety-green coloration on their upper bodies. Their undersides are typically a bright, shiny metallic green or gold, often featuring longitudinal stripes of yellow-orange or tan along the edges of their front wings (elytra).
Adults are active during the day, flying low and erratically with a noticeable, loud buzzing sound. The larval stage, or grub, is also distinct; these grubs can grow up to two inches long and are easily recognizable because they crawl on their backs, using stiff bristles on their abdomen for movement.
Understanding the Damage They Cause
The damage caused by the Green June Beetle is often less severe than perceived. Adult beetles primarily feed on very ripe or overripe, thin-skinned fruits, such as peaches, figs, grapes, and berries. They use a small horn-like protrusion on their head to break the skin and are strongly attracted to fermenting sap and sugary substances, causing them to aggregate in orchards. They rarely feed on plant leaves.
The grubs are distinct from other turf-damaging white grubs because they are primarily detritivores, feeding mostly on decaying organic matter like compost, mulch, and manure, rather than grass roots. Their main issue is the mechanical disruption of the soil surface. Tunneling activity creates small mounds of soil that can loosen the turf and cause minor damage to lawns.
Effective Strategies for Management
Managing Green June Beetles involves non-chemical and cultural practices addressing both life stages. For adults, physical exclusion is the most direct method to protect vulnerable crops. This involves covering ripening fruits with fine mesh netting or paper bags to prevent access. Homeowners can also physically remove the sluggish adults by hand-picking them or sweeping them into soapy water.
To manage the grubs, cultural practices focus on making the environment less appealing for egg-laying. Reducing organic matter, such as thick thatch layers or excessive compost, helps deter settling. Improving soil drainage and aerating the lawn promotes turf health, allowing grass to recover more easily from minor tunneling damage. Curative insecticide applications, often containing carbaryl or trichlorfon, can be used against young grubs in late summer, but they must be applied to the soil surface where the grubs feed at night. Biological controls like milky spore disease are ineffective against this grub, making cultural controls the preferred approach.