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Species Profile

Ten-Lined June Beetle

Polyphylla decemlineata

Ten stripes. One big night flier.
GypsyPictureShow/Shutterstock.com

Ten-Lined June Beetle Distribution

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Endemic Species
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Ten-Lined June Beetle

At a Glance

Wild Species
Also Known As Ten-lined June bug, Ten-lined May beetle, Ten-lined beetle, June bug
Diet Herbivore
Activity Nocturnal+
Lifespan 2.5 years
Status Not Evaluated
Did You Know?

Adults are typically 2.0-2.8 cm long, making them one of the larger conspicuously striped June beetles in western North America (field-guide measurements; e.g., Evans & Hogue).

Scientific Classification

A large, conspicuously striped scarab beetle (a “June beetle”) known for its bold cream-on-brown longitudinal lines on the wing covers and for adult activity in late spring to summer. Adults are often attracted to lights at night; larvae are soil-dwelling “white grubs.”

Kingdom
Animalia
Phylum
Arthropoda
Class
Insecta
Order
Coleoptera
Family
Scarabaeidae
Genus
Polyphylla
Species
decemlineata

Distinguishing Features

  • Large scarab beetle with multiple pale longitudinal stripes on the elytra (commonly described as ten lines)
  • Lamellate (fan-like) antennae typical of scarab beetles
  • Adults frequently fly at dusk/night and are attracted to artificial lights
  • Larvae are C-shaped white grubs living in soil

Physical Measurements

Length
1 in (1 in – 1 in)

Appearance

Primary Colors
Secondary Colors
Skin Type Hard, sclerotized chitinous exoskeleton; elytra and pronotum densely clothed in scales/setae; robust scarab body with lamellate antennal clubs.
Distinctive Features
  • Adult body length typically ~2.5-3.5 cm (commonly cited in western North American field guides and extension references).
  • Elytra show strong cream-on-brown longitudinal striping; lines are made by pale scales/setae rather than pigment.
  • Large, heavy-bodied scarab with convex pronotum and thick legs adapted for digging.
  • Antennae end in a lamellate club (Scarabaeidae); club can be fanned open, especially in males.
  • Nocturnal adult behavior: flies at dusk/night and is strongly attracted to artificial lights; adults often found at porch lights in late spring-summer.
  • Adult seasonal activity typically late spring through summer in western North America (often peaking June-July, varying with elevation/latitude).
  • Larvae are soil-dwelling C-shaped 'white grubs' with creamy bodies and brown head capsules; feed on plant roots.
  • Life cycle commonly reported as multi-year in soil (often ~2-3 years larval development in many populations), with adults emerging for a comparatively short breeding/flight period.

Sexual Dimorphism

Males have a noticeably larger, longer lamellate antennal club used for detecting female pheromones; females have a shorter club and a stouter, more egg-filled abdomen when gravid. Body length overlaps, but males often appear more 'antenna-heavy.'

  • Enlarged lamellate antennal club (more elongated and conspicuous when fanned).
  • Often slimmer overall profile, with proportionally longer antennae relative to head.
  • More active flier during dusk/night while searching for mates; commonly seen at lights.
  • Smaller/shorter lamellate antennal club.
  • Typically broader abdomen, especially when gravid; overall 'stockier' look.
  • More associated with oviposition sites; may be less frequently observed flying than males.

Did You Know?

Adults are typically 2.0-2.8 cm long, making them one of the larger conspicuously striped June beetles in western North America (field-guide measurements; e.g., Evans & Hogue).

The "ten lines" are longitudinal pale stripes on the elytra; each elytron bears five, giving 10 total when viewed from above-hence decemlineata ("ten-lined").

Males have dramatically enlarged, fanlike (lamellate) antennae used to detect female scent cues-an iconic Scarabaeidae trait shared across many scarabs.

Adults are strongly attracted to artificial lights at night, so porch lights can act like unintended "beetle traps" during flight season (commonly reported in extension pest notes).

The immature stage is a C-shaped, soil-dwelling white grub that feeds on roots; Polyphylla grubs can be turf and nursery pests when abundant (e.g., western U.S. extension and forestry pest manuals).

Their life cycle is long for a beetle: larvae commonly develop in soil for about 2-3 years (reported for P. decemlineata in western pest references), then adults live only weeks-long enough to mate and lay eggs.

Polyphylla is a diverse genus (dozens of species in North America) sharing the same basic scarab blueprint-lamellate antennae, digging legs, and multi-year grub stages-but varying widely in striping, habitat, and emergence timing.

Unique Adaptations

  • Lamellate (leaflike) antennal clubs: expandable plates increase sensory surface area-especially pronounced in males-enhancing detection of chemical cues in nighttime air (a hallmark adaptation of scarabs).
  • Bold longitudinal striping: the cream-on-brown pattern helps break up the beetle's outline among sandy soils, dry grasses, and leaf litter typical of many western habitats.
  • Powerful fossorial legs: spined tibiae and strong claws allow both adults and larvae to dig; adults can quickly bury themselves, and larvae stay protected in soil for years.
  • Multi-year larval development: spending ~2-3 years underground buffers the species against bad seasons and short adult windows; this strategy is widespread among "white grub" scarabs.
  • Tough elytra: hardened wing covers protect the abdomen and folded hindwings while the beetle pushes through abrasive soil and debris.

Interesting Behaviors

  • Nocturnal flight and "light-flying": adults take wing after dusk and are frequently drawn to streetlights and porch lights, where they circle repeatedly before dropping to the ground.
  • Burrowing and daytime hiding: during the day, adults typically remain sheltered (often in soil or under debris), reducing water loss and predation risk.
  • Root-feeding grub foraging: larvae move through soil and feed on fine roots; in lawns and nurseries, this can produce patchy wilting where grub densities are high.
  • Seasonal synchronized emergence: adults appear mainly in late spring through summer (often May-July depending on latitude/elevation), creating short, noticeable "flight seasons."
  • Mating behavior tied to scent detection: males actively search for females using their large lamellate antennae, which increase surface area for odor detection-common across Scarabaeidae.
  • Defensive stillness: when disturbed, adults may stop moving and tuck in legs (a common beetle anti-predator tactic), then suddenly buzz away when handled.

Cultural Significance

The ten-lined June beetle (Polyphylla decemlineata) is a loud, clumsy night flyer often drawn to lights. As a Scarabaeidae scarab, it ties to change and rebirth (ancient Egypt). Its long-lived grubs can harm lawns and roots, worrying farmers and gardeners.

Myths & Legends

In Ancient Egypt, scarab beetles (Scarabaeidae) were linked to the sun's daily rebirth; the god Khepri was shown as a scarab pushing the sun, a long myth about renewal.

In 19th–20th century rural North America, children tied a thread to a Ten-lined June beetle (Polyphylla decemlineata) and let it buzz in circles as a living toy, a common seasonal folk story.

Name-origin lore: the common name "June beetle/June bug" reflects the well-known seasonal appearance of adult scarabs; for P. decemlineata the striking 'ten lines' became a direct, descriptive naming story repeated in regional natural-history writing.

Conservation Status

NE Not Evaluated

Has not yet been evaluated against the criteria.

Population Unknown

Life Cycle

Birth 60 larvas
Lifespan 3 years

Lifespan

In the Wild
2–3 years
In Captivity
2–3 years

Reproduction

Mating System Polygynandry
Social Structure Solitary
Breeding Pattern Transient
Fertilization Internal Fertilization
Birth Type Internal_fertilization

Adults (~2-3 cm) are nocturnal and fly in late spring-summer; males locate females by pheromones and mate briefly, with both sexes able to remate. Females oviposit in soil and provide no parental care; larvae develop 2-3 years.

Behavior & Ecology

Social Congregation Group: 1
Activity Nocturnal, Crepuscular
Diet Herbivore Pine needles (Pinus spp.)
Seasonal Hibernates

Temperament

Generally non-aggressive; when disturbed, adults often drop and remain motionless (thanatosis) (Cranshaw, 2004; UC IPM, scarab beetle notes).
Adults fly at dusk and night; strong attraction to artificial lights increases local crowding (Cranshaw, 2004; Furniss & Carolin, 1977).
Across observed encounters, most individuals are solitary; congregation size varies widely with light intensity, weather, and local emergence density.
Life history timing relevant to social contact: soil-dwelling larvae develop about 2-3 years; adults are short-lived for several weeks during late spring-summer flight period (Cranshaw, 2004; Furniss & Carolin, 1977).

Communication

No true vocalizations documented; flight produces audible buzzing from wingbeat.
Occasional friction sounds (stridulation) are possible in scarabs, but species-specific evidence is limited.
Chemical mate-finding cues Sex pheromones inferred from scarab biology; males use enlarged lamellate antennae to locate females
Tactile contact during courtship and copulation; antennal tapping and body positioning.
Visual/phototactic orientation: adults strongly orient to light sources, indirectly concentrating individuals.

Habitat

Biomes:
Temperate Forest Mediterranean Temperate Grassland
Terrain:
Mountainous Hilly Plateau Plains Valley Coastal Sandy Riverine +2
Elevation: Up to 7874 ft

Ecological Role

Soil and foliage herbivore (root-feeding larva; defoliating adult) that can act as a periodic pest in forestry and some agricultural/landscape settings, while also serving as prey for insectivorous wildlife.

Transfers plant biomass to higher trophic levels (important prey item for birds, small mammals, and other predators) Soil bioturbation and aeration via larval tunneling/movement Influences plant community dynamics through selective root and foliage herbivory Contributes to nutrient cycling through frass production and eventual decomposition of life stages

Diet Details

Other Foods:
Roots of grasses and herbaceous plants Roots of seedlings and young woody plants Pine needles Tree and shrub foliage

Human Interaction

Domestication Status

Wild

Polyphylla decemlineata (ten-lined June beetle) is a wild North American scarab with no domestication history. People sometimes collect adults for displays or teaching because they are large, striped, and come to lights. Larvae are white grubs that eat roots and can harm plants. The species is studied for pest control and monitoring.

Danger Level

Low
  • No venom and no medically important bite; at most, a defensive pinch/scratch from spiny legs or mandibles if handled roughly.
  • Nuisance risk: strong attraction to lights can lead to frequent human contact around porches/garages.
  • Rare/indirect: potential mild allergy/asthma trigger from insect fragments/dust in sensitive individuals (non-specific to this species).

As a Pet

Not Suitable as Pet

Legality: Ten-lined June beetle (Polyphylla decemlineata) adults are usually legal to keep if collected locally in much of the U.S., but moving live beetles or larvae across state lines may be restricted; check state agriculture/plant protection and park rules.

Care Level: Experienced

Purchase Cost: Up to $25
Lifetime Cost: $20 - $150

Economic Value

Uses:
Pest (larval root-feeder) in forestry/agriculture Nuisance insect around lights (adult phototaxis) Education/entomology outreach and specimen collecting Biodiversity monitoring via light-trap bycatch
Products:
  • Negative: larvae ('white grubs') can injure roots of plants (documented for Polyphylla spp.; P. decemlineata is treated in western North American pest literature as a root-feeding scarab that may damage seedlings/roots in sandy soils).
  • Negative: adults congregate at artificial lights, creating nuisance and occasional minor damage from feeding on foliage/needles depending on local host use.
  • Positive: supports education (live observation of metamorphosis) and scientific collections (voucher specimens for distribution/phenology).
  • HUBS: In the broader June beetle/scarab group, economic impacts range from severe crop/turf/forest root-grub pests (some Melolonthinae/Rutelinae) to beneficial dung beetles (Scarabaeinae) that provide high-value ecosystem services; Polyphylla are primarily known on the pest/nuisance/education end of this spectrum.

Relationships

Predators 5

Common nighthawk Chordeiles minor
Little brown bat
Little brown bat Myotis lucifugus
American Crow Corvus brachyrhynchos
European starling
European starling Sturnus vulgaris
Striped skunk Mephitis mephitis

Related Species 5

Pine chafer Polyphylla fullo Shared Genus
Polyphylla crinita Polyphylla crinita Shared Genus
Hammond's June beetle Polyphylla hammondi Shared Genus
May/June beetles Phyllophaga spp. Shared Family
Green June beetle
Green June beetle Cotinis nitida Shared Family

Ecological Equivalents 4

Animals that fill a similar ecological role in their ecosystem

May and June beetles Phyllophaga spp. Similar life history: soil-dwelling white-grub larvae that feed on plant roots; adults are often nocturnal, seasonally abundant in late spring and summer, and commonly attracted to lights.
Green June beetle
Green June beetle Cotinis nitida Occupies a comparable seasonal 'June beetle' niche: large scarab adults active in summer, often encountered around human lights. Larvae, however, typically develop in rich organic soils or compost rather than feeding primarily on roots.
European chafer Amphimallon majale Ecological analog in managed turf and grass systems: scarab white grubs feed on grass roots in the soil and adults fly seasonally; often compared in discussions of grub damage.
Japanese beetle
Japanese beetle Popillia japonica Another scarab with soil-dwelling grubs and conspicuous adult activity. It differs by stronger adult foliar feeding and aggregation but overlaps in impacts: root-feeding larvae and adult flights in warm months.

Ten-lined June beetles are members of the Scarabaeidae family and fall into the class Insecta. They occur all over the globe and are known for their unique wings, which are covered in linear patterns.

They also go by the name watermelon beetles and have very poor eyesight, which is why they are so attracted to lights. Unfortunately, their fascination for lights is their downfall because it makes them easier to catch in backlight cages and other gadgets.

Ten-lined June beetles are native to the Northern Hemisphere, with dense populations in the United States and Canada.

Their primary diet consists of tree roots; however, they also like to drink grapefruit and raspberry juice. These beetles are known as pests because they can cause the trees they feed on to decay. While the larvae can live for around 4 years, adults barely survive for more than 10 months.

Ten-Lined June Beetle Species, Types, and Scientific Name

The ten-lined June beetle’s scientific name is Polyphylla decemlineata, and the genus consists of 85 species, which include:

Saline Valley Snow-front Scarab

The saline valley snow-front scarab (Polyphylla anteronivea) is also known as the saline valley snow-front June beetle, and they belong to the family Scarabaeidae.

This species is native to North America. Their ideal habitat is forests or orchards, and they are distinguished by their white elytra scales that form stripes down their bodies. Unfortunately, adults are drawn to lights, which often leads to death.

Saline valley snow-front scarabs lay their eggs in the soil, usually close to plants where the larvae hatch and bore down into the roots, where they will live and feed for two to three years before morphing into pupae.

Spotted Warner Valley  June Beetle

Spotted Warner valley June beetles primarily occur in the Northern Hemisphere and mainly emerge during warm spring evenings; they, too, are attracted to lights. They vary in size from 0.5 to 1 inch, and have metallic wings (elytra) that cover most of their bodies.

These beetles are nocturnal and feed on flowers and foliage, often causing extensive damage. Their larvae are called white grubs and measure around an inch in length, burrowing into the soil where they stay for years.

In addition to damaging flowers, they also destroy:

  • Corn fields
  • Small grains
  • Potatoes
  • Strawberries
  • Lawns
  • Pastures

Mount Hermon June Beetle

The Mount Hermon June beetle originated in Santa Cruz County, California, where it was first discovered in 1938. The males are petite with black heads and dark brown elytra, which are covered in long brown hair. In addition, they have stripes all over their bodies. These stripes are broken and usually resemble discontinuous clumps.

The females are more prominent and also have black heads; however, the lower part of their faces are chestnut in color. In addition, their head, thorax, and legs are covered in golden hair. The difference in size between this species’ sexes is quite significant, with females measuring 0.87 by 0.43 inches and males 0.79 by 0.39 inches.

Order

Ten-lined June beetles belong to the order Coleoptera and are best distinguished by their front pair of wings called elytra. This order is the largest of the Insecta class and contains around 400,000 species, with new specimens discovered often.

Family

They are members of the family Scarabaeidae, who are recognized for their stout bodies and metallic colors. Members vary in size and can measure between 0.059 to 6.2 inches.

One of their distinguishing features is their clubbed antennae that compress into a ball or fawn out like leaves, which they use to sense odors.

In addition, many species in this family are burrowers, and have legs adapted for digging. Some adult species have horns on their head, which they use to fight over resources or mates. The largest species ever found was fossilized, named Oryctoantiquus borealis, and it measured 2 inches long.

Appearance: How To Identify the Ten-Lined June Beetle

The ten-lined June beetle is best recognized by the four white lines running down its elytra. In addition, they have antennas with lamellate plates. Their coloring differs depending on the sex, but they are generally black or reddish-brown in color.

These beetles are usually between 0.8 to 1.5 inches long. However, the grubs can reach lengths of 2 inches if they receive proper nutrition. When compared to the Hercules beetle, they are nearly half the size!

Habitat: Where to Find the Ten-Lined June Beetle

These beetles occur throughout the Northern and Western United States and Canada. However, large populations inhabit states like:

  • Kansas
  • Arizona
  • California
  • Nebraska
  • Nevada
  • Colorado

They prefer to live in forests, shrublands, and farmlands and are considered agricultural pests because tin-lined June beetles’ larvae live in the soil and feed on the roots of plants, destroying them in the process.

Diet: What Do Ten-Lined June Beetles Eat?

The diet of ten-lined June beetles varies, but they primarily feed on plant-based food like

  • Leaves
  • Walnut trees
  • Oak trees
  • Plant roots

The grubs are detrimental to plants because they cause decay when feeding on the roots.

Life Cycle of the Ten-Lined June Beetle

The life cycle of ten-lined June beetles is relatively long for an insect. These beetles can take up to two years to complete one generation. In fact, larvae can develop in soil for up to 4 years!

The larvae inhabit the top soil (around 14 inches from the surface), where they feed on roots. Adult females will make their way to the surface every summer or early autumn and release pheromones to attract males.

Around this time, males will fly around from dusk until midnight in search of a mate. Once the mating is over, the females burrow back into the soil to lay their eggs.

While the larvae can live up to four years, there is no record of the lifespans of adults; however, it is thought that they die after laying eggs.

Prevention: How to Get Rid of the Ten-Lined June Beetle

Unfortunately, the only way to exterminate heavily infested areas is by removing the trees, and the surrounding soil needs to be fumigated to prevent the larvae from claiming nearby trees.

In addition, commercial growers apply soil insecticides to kill the larvae as aboveground chemicals do not work.

However, these methods only apply to large areas like forests. Home gardens are a different story. Female ten-lined beetles cannot fly, so populations spread slowly, making them easily manageable in a small space.

Homeowners can use lights to attract these beetles and capture them with a net. Some people feed them to their chickens, while others squish them once caught.

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Sources

  1. The Daily Garden / Accessed September 13, 2022
  2. Encyclopedia encyclopedia.com/environment/science-magazines/mount-hermon-june-beetle / Accessed September 13, 2022
  3. Wikipedia / Accessed September 13, 2022
  4. Kidadl / Accessed September 13, 2022
Chanel Coetzee

About the Author

Chanel Coetzee

Chanel Coetzee is a writer at A-Z Animals, primarily focusing on big cats, dogs, and travel. Chanel has been writing and researching about animals for over 10 years. She has also worked closely with big cats like lions, cheetahs, leopards, and tigers at a rescue and rehabilitation center in South Africa since 2009. As a resident of Cape Town, South Africa, Chanel enjoys beach walks with her Stafford bull terrier and traveling off the beaten path.
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Ten-Lined June Beetle FAQs (Frequently Asked Questions)

These beetles are usually between 0.8 to 1.5 inches long. However, the grubs can reach lengths of 2 inches if they receive proper nutrition.