The June bug, most often referring to species within the genus Phyllophaga, is a widespread insect that appears during the warmer months. These reddish-brown beetles are commonly seen flying near lights on summer evenings. A closer look at their anatomy reveals how this insect interacts with its environment and consumes food.
The June Bug’s Mandibles
June bugs possess a pair of appendages near their mouth that function as jaws, known scientifically as mandibles. These structures are a defining characteristic of beetles (order Coleoptera) and are built for a chewing lifestyle. The mandibles are hardened, chitinous structures that operate horizontally, moving side-to-side like a pair of shears. The primary function is to grasp, cut, and grind solid food materials, typically slicing through vegetation. Though these insects have functional chewing mouthparts, they are not designed or used for defensive biting of humans or other large animals.
Adult Feeding and Chewing
The adult June bug is a nocturnal herbivore, using its mandibles primarily to consume plant tissue under the cover of darkness. Their diet consists mainly of the foliage of various trees, including common deciduous species like maple, oak, and hickory. The adult beetles will clip and chew the edges of leaves, a feeding behavior known as phytophagy. These specialized mouthparts allow the adult to process relatively tough plant fibers efficiently.
The adult stage is relatively short, lasting only a few weeks. Damage caused by adult feeding is generally considered minor and cosmetic unless the population density is extremely high.
Larval Feeding Habits and Role
The larval stage of the June bug, commonly called a white grub, possesses strong, chewing mouthparts that serve a different purpose underground. These grubs spend the majority of the June bug’s 1- to 4-year life cycle burrowed in the soil. Their mandibles are crucial for cutting and consuming the fine roots of plants, along with decaying organic matter. This subterranean feeding habit makes the grub the most destructive life stage for homeowners and agriculture.
The larvae chew through the root systems of turfgrass, leading to large, irregular patches of brown, dying lawn that can be rolled back like a carpet. They also cause significant damage to crops like corn, potatoes, and strawberries by severing the plants from their water and nutrient supply.