Junebugs, also known as May beetles, are a familiar sight in late spring and early summer. These common beetles often make their presence known by clumsily bumping into windows or buzzing around outdoor lights. While their sudden appearance can be startling, understanding these insects, which become active above ground during these months, can help people appreciate their role in the natural world.
Identifying Junebugs
Adult junebugs measure between 0.5 to 1 inch long, with a thick, oval, and robust body. Their coloration ranges from reddish-brown to darker brown, though some species may be metallic green. A distinguishing feature is their hard, shell-like wing covers, called elytra, which protect their delicate flying wings. These insects have six legs and distinctive antennae for navigation. Junebugs are clumsy fliers, often bumping into objects during nocturnal flights, but their characteristic appearance makes them relatively easy to identify.
The Junebug Life Cycle
Junebugs undergo complete metamorphosis, progressing through four stages: egg, larva, pupa, and adult. The life cycle typically spans one to three years, with many species completing it over three years. Females bury themselves 2 to 5 inches deep in the soil to lay 60 to 75 pearl-like eggs over two weeks during midsummer.
Eggs hatch into small, white larvae, called white grubs, after two and a half to four weeks. These C-shaped grubs have a cream-colored body, a brown head, and three pairs of legs, growing up to 1.6 inches long. The larval stage is the longest, as grubs feed on plant roots underground for one to three years.
After this, grubs transform into pupae 3 to 6 inches deep in the soil. This pupal stage lasts about three weeks, as the insect reorganizes into its adult form. Adult junebugs emerge from the soil in late spring to early summer, living above ground for less than a year to mate and restart the cycle.
Why They Appear
Junebugs are nocturnal insects, active during nighttime hours. This explains why they are frequently observed buzzing around light sources after dusk. They are strongly attracted to artificial lights, a phenomenon known as positive phototaxis.
This attraction is thought to stem from their natural navigation system, where they may confuse artificial lights for celestial bodies like the moon. Some theories also suggest males are drawn to lights to locate potential mates. Junebugs are most active from late spring through early summer, when adult beetles emerge from the soil. They prefer habitats like lawns and gardens with suitable foliage to feed upon.
Impact on Gardens and Homes
Junebugs can affect gardens and landscapes differently depending on their life stage. Adult beetles feed on the leaves of trees, shrubs (including oak, walnut, maple, apple, peach, and roses), and flowers. While their feeding leaves ragged holes, adult junebug damage is not extensive.
The more significant impact comes from their larval stage, the white grubs, which reside underground. These grubs feed on plant roots, including grasses, weeds, vegetable transplants, and ornamental plants. Extensive grub feeding can damage lawns, appearing as yellowing or browning patches, and may cause the ground to feel spongy. Severely damaged grass can be lifted easily from the soil, similar to rolling up a carpet.
The presence of these grubs can also attract larger animals like moles, raccoons, and skunks, which dig up lawns in search of food. While junebugs do not bite or sting humans, their grub stage can pose challenges for maintaining healthy lawns and gardens.