June beetles, often called May beetles, are common scarab beetles (Phyllophaga) that emerge in late spring and early summer. These insects are recognizable by their robust, reddish-brown bodies and clumsy, buzzing flight on warm evenings. Despite their startling appearance and noisy presence, June beetles are not poisonous or dangerous to humans or household pets. Their nocturnal emergence makes them a nuisance rather than a threat to health and safety.
Clarifying the Threat: Poisonous, Venomous, or Harmless?
June beetles pose no chemical threat because they are neither venomous nor poisonous. Venomous animals inject toxins, while poisonous organisms release toxins when ingested. June beetles lack the specialized biological apparatus to deliver toxins. They possess no stingers and their body tissues contain no known poisons that would be harmful if consumed.
June beetles do not carry diseases transmissible to people or pets, removing them from the category of a health risk. Adult beetles primarily feed on plant foliage, and their mandibles are adapted only for chewing leaves, not for breaking skin. Their harmless nature is consistent across the hundreds of species within the Phyllophaga genus. The only danger they present is to vegetation, where their larvae, known as white grubs, can damage lawn and garden roots.
Risks Associated with Physical Contact
Although June beetles are not chemically harmful, physical interactions can cause worry. An adult June beetle does not bite, as its mouthparts are too weak to penetrate human or animal skin. If roughly handled, the beetle’s spined legs may cause a slight, purely mechanical pinching sensation as a defensive reaction. This results in no injury beyond a momentary surprise.
Ingesting June beetles is a common scenario for pets, particularly dogs. While the beetles are not toxic, their hard, chitinous exoskeleton is largely indigestible. Eating one or two beetles typically causes no ill effects, but consuming a large quantity may cause gastrointestinal upset, resulting in mild vomiting or diarrhea.
In rare instances, the accumulation of undigested exoskeletons can lead to a gastrointestinal blockage, especially in smaller dog breeds. A greater risk comes from pesticide residue if the beetle was recently exposed to lawn chemicals. Pet owners should monitor for persistent vomiting or lethargy if a pet consumes a large number of these insects.
Why People Worry: Misidentification and Appearance
Concern over June beetles often stems from their physical characteristics and startling presence. The beetles are large, measuring up to an inch in length, and their clumsy flight pattern often leads them to collide with objects and people. This erratic movement, combined with the loud, persistent buzzing noise, can make them seem aggressive or threatening, especially when swarming outdoor lights at night.
The common name “June bug” is used broadly for many scarab species, leading to confusion with other insects. For instance, the metallic-green June beetle (Cotinis nitida) is often confused with the invasive Japanese beetle, which is a greater plant pest. This widespread and inaccurate application of the common name contributes to anxiety surrounding their safety, despite the adults being completely harmless.