June Beetle

June beetles, also called June bugs or May beetles, are chunky brown scarab beetles that buzz around porch lights on warm late-spring and early-summer evenings. They get their name from the time of year when the adults dig out of the ground. Their larvae, called white grubs, live in the soil and feed on plant roots.

June beetle Quick Facts

Common name	June beetle
Scientific name	Phyllophaga
Kingdom	Animalia
Phylum	Arthropoda
Class	Insecta
Order	Coleoptera
Family	Scarabaeidae
Type	Insect (scarab beetle)
Diet	Adults: tree leaves; grubs: plant roots
Habitat	Lawns, fields, woodland edges and gardens
Native range	North and South America (Phyllophaga)
Size	About 12-35 mm long
Lifespan	Often 1-3 years, mostly as underground grubs
Colours	Reddish-brown to dark brown

What are June beetles?

“June beetle” is a common name rather than one species. In North America, it usually means the hundreds of species in the genus Phyllophaga, part of the scarab family (Scarabaeidae) and the chafer subfamily Melolonthinae. The name is also used for some other beetles that appear in early summer, including the green June beetle and its relatives.

June beetles are found across the Northern Hemisphere, and Phyllophaga species live throughout much of North, Central and South America.

What do June beetles look like?

Typical Phyllophaga June beetles are about 12 to 35 mm (0.5 to 1.4 inches) long, with a heavy, rounded body. They are reddish-brown to dark brown or almost black, and their wing covers (elytra) are smooth and slightly shiny. Like all insects, they have six legs, and their legs have sharp, hooked claws that can cling to screens and clothes.

They have chewing mouthparts and short antennae that end in a small fan of flat plates. Males have bigger antenna fans than females, which helps them smell females at night.

What do June beetles eat?

Adult June beetles feed at night on the leaves of trees and shrubs, such as oak trees, walnut, hickory, willow and poplar. They usually do not cause much harm to healthy trees.

The grubs are the hungry ones. They live underground and chew the roots of grasses, cereal crops like corn and wheat, and many garden plants.

Life cycle

Many northern June beetles take about three years to grow from egg to adult, although some species take one, two or four years. Most of that time is spent underground as a grub.

• Eggs. In early summer, after mating, the female burrows a few inches into the soil and lays her eggs, often in small balls of earth. The pearly white eggs start out oval and become rounder as the larva grows inside. They hatch in about two to three weeks.
• Grubs. The larvae are C-shaped, creamy white grubs with brown heads and six small legs. They feed on roots and molt twice, passing through three stages called instars. Each winter they dig deeper into the soil, below the frost, and in spring they move back up to feed near the surface.
• Pupae. When fully grown, the grub builds a small chamber of soil and turns into a pupa for about three weeks.
• Adults. The new adult often rests in the soil through the winter and comes out the following late spring or early summer to feed and find a mate.

Attracted to lights

June beetles fly mostly at night, and they are strongly attracted to bright lights. That is why they bump against windows, crash into porch lights and sometimes get tangled in people’s hair. They are clumsy fliers, but they are completely harmless: they do not bite or sting.

Are June beetles pests?

Adult June beetles are mostly a nuisance around lights. The grubs are the real pests. When there are lots of them, they can kill patches of lawn and damage pastures and crops by eating the roots. Young plants and seedlings can wilt, turn reddish-brown and die.

Grubs also attack garden plants and crops such as corn, potatoes, strawberries, raspberries and young nursery trees.

To keep June beetles in check without chemicals, turn off or dim outdoor lights at night, or use yellow bulbs, which attract fewer insects. Keep lawns thick and healthy so they can cope with some grubs. Birds, toads, moles and skunks eat lots of grubs, and beneficial nematodes, tiny worms sold for gardens, can be watered into lawns to attack grubs too.

Types of June beetles

The name “June beetle” is used for many different scarab beetles from two subfamilies. Here are some of the best-known.

Flower chafers (subfamily Cetoniinae)

Green June beetle (Cotinis nitida)

Green June beetle. Photo by: Katja Schulz

The green June beetle lives in the eastern United States, especially in the south and east. Adults are about 15 to 22 mm long, with dull, velvety green wing covers edged with tan or gold, and a shiny metallic green underside and legs. Unlike most June beetles, it flies by day, often buzzing low over lawns. Adults feed on ripe fruit, and the grubs eat decaying plant matter in the soil.

Figeater beetle (Cotinis mutabilis)

Green fruit beetle. Photo by: Michal Chik

The figeater, also called the fig beetle or green fruit beetle, lives in the southwestern United States and Mexico. Like other scarab beetles in its group, it is a strong daytime flier. Adults are about 3 cm long, matte green on top and bright shiny green underneath, and they love soft, ripe fruit, especially figs. In flight they make a loud buzz, a lot like carpenter bees.

Chafers and May beetles (subfamily Melolonthinae)

Summer chafer (Amphimallon solstitiale)

European June beetle. Photo by: entomart

The summer chafer, sometimes called the European June beetle, looks like a smaller, hairier cockchafer and is about 14 to 18 mm long. It lives across Europe and parts of Asia. On warm evenings in June and July, swarms fly around the tops of trees at dusk looking for mates, and they often fly toward lit windows.

Cockchafers (Melolontha)

Cockchafer (Melolontha). Photo by: Mario Sarto

Melolontha is a genus of large chafers from Europe and Asia. The best-known is the common cockchafer, or May bug, which is about 2.5 to 3 cm long, with reddish-brown wing covers, a black thorax and white triangles along its sides. Its grubs spend three to four years in the soil.

May beetles (Phyllophaga)

May beetle. Photo by: Anders Sandberg

Phyllophaga is a huge genus of hundreds of species from the Americas. These are the classic brown June bugs and May beetles of North America, about 12 to 35 mm long and reddish-brown to blackish. They are active at night and are strongly attracted to lights.

Ten-lined June beetle (Polyphylla decemlineata)

Ten-lined June beetle, also called the watermelon beetle.

This big, striking beetle lives in western North America, from southern Canada to the western United States. It is brown with bold white stripes down its back, which give it its name. Adults are drawn to lights and feed on the leaves of trees, especially conifers. When picked up, it makes a loud hissing squeak by rubbing parts of its body together. Its large grubs feed on roots and can damage crops, young trees and garden plants.

Rhizotrogus marginipes

Rhizotrogus marginipes

This chafer is a European species, found in countries including France, Italy, Switzerland, Germany and parts of the Balkans. Like its relatives, its grubs live in the soil and feed on roots.

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