The green June beetle (Cotinis nitida) is a large, metallic green scarab beetle that is common in early summer across the eastern United States. Their emerald green shells glint brightly in sunlight, making them easy to spot as they feed and fly through lawns and landscapes.
If you’ve spotted these large beetles recently and want to know more, here we’ll cover everything about the green June beetle’s identification, life cycle, damage potential, and control.
Identifying the Green June Beetle
Appearance and Size
The Green June Beetle is a striking metallic green color that makes it easy to identify. Adults range in size from 12-25 mm long with a width of 7-12 mm, making them slightly smaller than the very common Japanese beetle.
The Green June Beetle’s oval body shape distinguishes it from most other beetles. Its legs and underside may have a tan, golden, or reddish-brown coloration. The wings are faintly yellow or light green.
Range and Habitat
Green June Beetles live across most of the eastern half of the United States. Their range extends from New York down to Florida and as far west as Texas. These beetles prefer warm environments and are especially common in the southeastern states.
Green June Beetle grubs live underground, feeding on the roots of grasses and plants. The adults emerge in late spring and are active throughout the summer.
Behavior and Sounds
The Green June Beetle is known for being especially noisy during mating season in late spring and early summer. The male beetles produce a loud buzzing sound by vibrating their abdomens to attract females. This sound led to their nicknames “June bug” and “June beetle.”
The Green June Beetle is clumsy and flies somewhat awkwardly, often crashing into objects. It flies most actively at dusk seeking food sources and mates.
| Green June Beetle Facts |
|---|
| – Metallic green body color |
| – 12-25 mm body length |
| – Found across eastern U.S. |
| – Males make loud buzzing sounds |
Green June Beetle Life Cycle
Eggs and Larval Stage
The fascinating life cycle of the Green June Beetle begins in mid to late summer when the adult females burrow 2-4 inches underground to lay up to 75 eggs. The eggs incubate underground throughout fall and winter.
When spring arrives, the eggs hatch into C-shaped grub larvae to feed on grass and plant roots. 😍 The larvae cause damage to lawns and turfgrass as they devour roots and burrow deep, munching away underground for over 10 months from spring to early summer.
The Green June Beetle grub is described by its greyish white body and brown head with strong jaws to grind up plant matter as it grows over 1 inch in length. The larvae go through three larval stages, or instars.
With each successive instar, the grub increases damage to plant roots and lawns as it increases in size and appetite! After completing development underground, the mature third instar stops feeding and moves deeper into the soil profile to prepare for transformation. 👏
Pupal Stage
In the next phase of the Green June Beetle life cycle, the mature larva transforms into the inactive pupal stage, losing the C-shape as it becomes more oval. The pupa has the basic form of the adult beetle. Pupation may last up to three weeks before the incredible emergence transpires.
When it is finally time for adult emergence in early summer, the brown pupa wriggles upwards towards the soil surface. Then the magic happens! 🎉 The pupal skin splits as the shiny green adult beetle squirms out and spreads its vibrant emerald wings for the first time.
The new adults will continue developing for a week or two before taking flight into the summer air.
Adult Stage and Mating
The Green June Beetle adult is active for four to six weeks during mid-summer into early fall. These gorgeous iridescent green scarab beetles grow to 1 inch in length and are described as noisy, clumsy fliers.
They become most active on warm summer evenings an hour before dusk, swarming attractions like lights, lush foliage, and ripe fruit. The bumbling beetles emit an audible buzzing hum as they fly, sometimes crash landing onto lawns.
- June bugs feed on ripening fruit like peaches, plums, apricots, etc. Munching damage can impact crop quality and yield.
- Adults also have a fondness for tree leaves like willow, maple, ash, etc., leaving behind skeletonized foliage.
During the few weeks of the adult stage, mating occurs with males locating females via pheromones and visual cues. After mating, each female lays dozens of eggs starting the amazing cycle again! Given the extended underground C-shaped larval grub stage, the Green June Beetle completes a 1 to 3 year life cycle.
What an epic journey full of fascinating transformations!
Damage Caused by Green June Beetles
Larval Damage to Lawns and Crops
The larval stage of the green June beetle (Phyllophaga spp. ), also known as the white grub, can cause extensive damage to lawns, pastures, crops, and nursery gardens across the Southern and Midwestern United States.
These C-shaped grubs feed on the roots of grasses and vegetables, destroying turf, reducing crop yields, and even killing plants.
Grubs chew through the roots, severing the plant’s connection to water and nutrients. This root pruning stunts growth and turns lawns brown. According to the University of Kentucky Entomology department, grubs can destroy up to 50% of turfgrass roots without visible damage above ground.
But higher grub densities rapidly thin out infested areas.
Crops such as corn, strawberries, potatoes, peanuts, and nursery stock are also at risk. Grubs tunnel through sweet potato tubers and munch on peanut pods still underground. Vegetables with compromised roots become more susceptible to drought stress and pathogens.
One grub per square foot of vegetable crops can result in 50% stand loss.
Adult Feeding Damage
After emerging from the soil as beetles in early summer, the adult green June beetles snack on over 350 species of fruit, vegetable, and ornamental plants. Swarms of these one-inch long insects skeletonize leaves and damage ripening fruit with their strong mandibles designed for chewing.
Favored fruits include peaches, apples, grapes, cherries, apricots, plums, pears, and figs. Hungry adult beetles also feed on corn silk, preventing pollination. And they snack on flowers such as zinnias, asters, dahlias, hollyhocks, and golden glows.
Skeletonized fruit is unmarketable due to deep scars. Skeletonized plant leaves have lace-like wholes and brown edges. They lose the ability to photosynthesize properly, suffer stunted growth, and drop early.
| Life Stage | Type of Damage |
|---|---|
| Larvae (grubs) | Feed on grass roots, destroying lawns; tunnel through crop roots and tubers |
| Adults | Skeletonize leaves of fruits, vegetables and ornamentals; scar ripening fruit |
Controlling and Preventing Green June Beetles
Cultural and Biological Controls
When it comes to keeping populations of the hungry green June beetle at bay, cultural and biological control methods tend to be the most environmentally friendly approaches. Methods like crop rotation, removing food sources, introducing natural predators, and using entomopathogenic fungi can help reduce green June beetle numbers without relying on chemical pesticides.
Crop rotation involves changing the crop grown in an area from year to year, interrupting the juvenile beetles’ life cycle development in the soil and starving local beetle populations. Removing rotting fruit, vegetables, and compost piles eliminates breeding and feeding sites.
Natural enemies like ants, ground beetles, pathogenic nematodes, birds, rodents, and parasitic flies and wasps can be introduced to prey on various green June beetle life stages.
Additionally, there are a couple types of entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae, that infect insects and have shown effectiveness against green June beetle larvae and adults.
These biological and cultural control methods may take time, but avoiding pesticide use leads to healthier soil, plants, and ecosystems.
Chemical Controls for Green June Beetle Grubs and Adults
When dealing with a serious beetle infestation, farmers often turn to chemical control options for quicker and more potent solutions. Insecticides and pesticides can effectively knock down both grub and adult populations but may also negatively impact beneficial species or lead to pesticide resistance if overused.
For grub management, Imidacloprid, Halofenozide, and Chlorantraniliprole are common choices with decent efficacy and plant safety when used properly. Spraying adult aggregates with permethrin, bifenthrin, carbaryl, or cyfluthrin can provide adult control.
It’s critical to adhere to all insecticide application guidelines and safety regulations. Scouting fields, accurate pest identification, using economic thresholds, and alternating modes of action helps prevent resistance issues.
Integrated pest management (IPM) programs take a combined approach for optimal, eco-friendly protection. They incorporate monitoring, thresholds, prevention, biological controls, and only utilize pesticides responsibly as a last resort when populations reach damaging levels.
Careful pesticide selection and application timing that avoids pollinators is also key.
Conclusion
With their large size and bright green metallic shells, green June beetles are eye-catching insects. While the grubs can damage lawns and crops if populations become severe, these beetles are generally more of a nuisance than causing real destruction.
By learning to recognize these beetles and being familiar with their life cycle and habits, you can take appropriate cultural or chemical control measures in your yard and garden if populations begin to rise.
