The term “June bug” is a common designation applied to several species of scarab beetles, most frequently those in the genus Phyllophaga, also known as May beetles or chafers. These reddish-brown, heavy-bodied insects emerge in late spring, marking the transition into the warmer months of summer. Understanding this insect involves looking beyond their clumsy, buzzing flight to explore what their sudden, seasonal presence indicates both environmentally and practically for homeowners.
Identifying the June Bug
The adult June bug is a stout beetle, typically measuring between one-half to one inch in length. The body is usually a shade of reddish-brown or dark brown, encased in a hard, shiny exoskeleton. These beetles are primarily nocturnal, often seen clumsily flying around outdoor lights after dusk, a behavior that frequently leads to them bumping into windows and screens.
Their larval form, commonly referred to as a white grub, is distinctly C-shaped with a cream-colored body and a brown or reddish-brown head capsule. The grub can grow up to an inch or more in length while living beneath the soil surface. The June bug is often confused with the Japanese beetle, which is smaller and features an iridescent, metallic green head and thorax, or the Green June Beetle (Cotinis nitida), which is easily distinguished by its velvety green or gold metallic coloring.
The Three-Year Life Cycle and Seasonal Timing
The appearance of the adult beetle in May or June is the culmination of a life cycle spent almost entirely underground. After emerging to mate, the female beetle burrows into the soil to lay between 50 and 200 eggs near the roots of grasses and plants. These eggs hatch into the white grubs within a few weeks, and this larval stage then becomes the longest phase of the insect’s life.
The grubs feed voraciously on plant roots and decaying organic matter for one to three years. They pass through three developmental stages, or instars, with the larvae growing larger and feeding more extensively with each stage. In the late summer or fall of their final year, the mature grubs move deeper into the soil to create a pupal chamber where they transform into adult beetles.
The adult beetles then remain in the soil over the winter, emerging only in late spring or early summer, which gives the insect its common name. Because the adult life span is relatively short, the main purpose of the emergence is to reproduce and begin the cycle anew. Due to overlapping generational cycles, a larger emergence of adult beetles may be observed in a given location every three years.
What the Presence of June Bugs Signifies
The visible presence of adult June bugs signifies the transition into the early summer period. Their flight activity is a natural seasonal indicator, closely tied to the environmental conditions necessary for their emergence and reproduction. The beetles themselves are a temporary, rich food source for numerous local predators, including bats, frogs, and various species of birds.
The abundance of June bugs also signals the health and function of a larger ecological food web in the area. The grubs and adults support the populations of insectivores, such as skunks, raccoons, and moles. Furthermore, as the larvae move through the soil, they contribute to the aeration of the ground and the recycling of nutrients from organic matter.
However, the presence of unusually high numbers of adults can also indicate a local imbalance, such as a large population of grubs that went unchecked in previous seasons. This high concentration suggests that the beetles found a suitable environment for egg-laying, often in lush turf, or that their natural predators may be less effective in the immediate area. Their large-scale emergence is a direct reflection of the unseen activity occurring beneath the soil.
Recognizing and Addressing Grub Damage
The most significant impact of the June bug is not the adult beetle, but the damage caused by the larval stage feeding on plant roots. These white grubs chew through the root systems of grasses, which prevents the turf from absorbing necessary water and nutrients. This feeding activity results in the appearance of irregular brown or dead patches in the lawn, particularly noticeable during dry periods.
A distinctive sign of severe grub damage is that the affected turf will feel spongy underfoot and can often be rolled back easily like a loose carpet, as the roots anchoring the grass are gone. The presence of small animals digging in the lawn, such as birds, skunks, or moles, is another strong indicator, as they are actively searching for the grubs. To confirm an infestation, a small square of turf should be peeled back to check the soil beneath. Finding five to ten grubs per square foot usually indicates a population size that will cause lawn damage.
The adult beetles feed on the leaves of trees and shrubs at night, which can result in a ragged, chewed appearance. Addressing the problem focuses primarily on the larval stage. Maintaining a healthy lawn through proper watering and mowing practices can help the grass tolerate minor infestations. If a high count of grubs is confirmed, targeted treatments, often applied in late summer when the grubs are small and feeding near the surface, are the most effective method for control.