The ten-lined June beetle (Polyphylla decemlineata) is one of the most visually distinctive scarab beetles in the American West. Adults are large (1–1.5 inches), with a striking pattern of white and brown longitudinal stripes on the wing covers — making them unmistakable among Arizona's scarabs. Males have enormous, fan-like antennae used to detect female pheromones. When disturbed, adults produce a loud hissing or squeaking sound by rubbing body parts together (stridulation), which startles predators and curious humans alike. Adults are nocturnal, strongly attracted to lights, and active from June through August, particularly at higher elevations in Arizona's mountain communities (Flagstaff, Prescott, Show Low). Adults feed on pine needles and other conifer foliage. The larvae are very large, C-shaped white grubs that live in the soil for three to five years, feeding on the roots of pines, firs, and other conifers. In forest nurseries and Christmas tree farms, ten-lined June beetle grubs can cause severe damage to young trees. In residential settings near pine forests, they occasionally damage ornamental conifers and turf.
👁Warning Signs
Large (1–1.5 inch) boldly striped white-and-brown beetles at lights in June–August, especially at elevation. Hissing sound when handled. Decline of young pine or conifer trees. Large white grubs in soil near conifers. Males with large fan-like antennae.
⚠Health & Property Risks
Root damage to young pines and conifers in nurseries and forest plantations. Occasional turf and ornamental damage near pine forests. Adults are alarming but harmless.
Prevention Tips
Protect young conifer seedlings with physical barriers. Reduce outdoor lighting at elevation properties. Apply preventive soil insecticides around high-value young conifers.
🛡Professional Treatment
Soil insecticides around affected conifers. Beneficial nematodes for organic management. Remove and replace severely damaged young trees. Consult a certified arborist for established trees.
Frequently Asked Questions — Ten-Lined June Beetle
The Ten-Lined June Beetle (Polyphylla decemlineata) is adults boldly striped white and brown; males with large fan-like antennae; grubs cream-white and typically measures Adults 1–1.5 inches; grubs proportionally large. The ten-lined June beetle (Polyphylla decemlineata) is one of the most visually distinctive scarab beetles in the American West. Adults are large (1–1.5 inches), with a striking pattern of white and b.
The Ten-Lined June Beetle poses a moderate risk. Root damage to young pines and conifers in nurseries and forest plantations. Occasional turf and ornamental damage near pine forests. Adults are alarming but harmless.
In Arizona, ten-lined june beetles are most often encountered in the following situations: Large (1–1.5 inch) boldly striped white-and-brown beetles at lights in June–August, especially at elevation. Hissing sound when handled. Decline of young pine or conifer trees. Large white grubs in soil near conifers. Males with large fan-like antennae.
The Ten-Lined June Beetle is most active during: Adults June–August; larvae active year-round with 3–5 year life cycle. Arizona's warm desert climate can extend activity periods compared to other states, so year-round vigilance is recommended in the Phoenix metro and surrounding areas.
Protect young conifer seedlings with physical barriers. Reduce outdoor lighting at elevation properties. Apply preventive soil insecticides around high-value young conifers.
Soil insecticides around affected conifers. Beneficial nematodes for organic management. Remove and replace severely damaged young trees. Consult a certified arborist for established trees.
Left unchecked, Ten-Lined June Beetle infestations can cause significant structural or food-storage damage over time. Root damage to young pines and conifers in nurseries and forest plantations. Occasional turf and ornamental damage near pine forests. Adults are alarming but harmless. Early detection and professional treatment are the most cost-effective approach — contact Pest Control Bros for an inspection at the first sign of activity.
Dealing with Ten-Lined June Beetle?
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