Bug FAQTen-lined June Beetle
Polyphylla decemlineata · Order: Coleoptera · Family: Scarabaeidae
Also called: 10-lined June Beetle
Source: Wikipedia
Ten-lined June beetles are relatively large, up to about 1.5 inches long, and have distinctive striped wing covers. They live in the western United States and Canada, where adults eat pine foliage and larvae eat plant roots, which can weaken or kill plants. The larval stage may last up to four years, and the beetles can make a hissing sound when disturbed.
Source: Wikipedia
Size
Adults can grow to about 1.5 inches (3 cm) or larger.
Source: Wikipedia
Does it bite or sting?
When disturbed they can produce a hissing sound by forcing air out between their wings.
Source: Wikipedia
What it eats
Larvae feed on plant roots, which can weaken or kill the host plant.
Source: Wikipedia
Life cycle
Eggs are oval, dull, creamy, and about 1/16 inch long.
Source: Wikipedia
Where it comes from
Their range includes western North America.
Source: Wikipedia
Lookalikes
They are often confused with Polyphylla crinita, the Long-Haired June Beetle, and need high-resolution photos to tell them apart.
Source: Wikipedia
Where it is found in the US
Recorded in 18 of 51 states and DC. Most records: California, New Mexico, Arizona, Colorado, Utah, Oregon, Washington, Idaho.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in Canada. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
Can they damage my garden or trees?
Yes, adult beetles eat pine needles and the larvae eat plant roots, which can weaken or kill trees and garden plants.
Source: Wikipedia
Same family (Scarabaeidae)
Japanese BeetlePopillia japonicaDamages trees, gardens or crops
Common Green June BeetleCotinis nitidaDamages trees, gardens or crops
Phyllophaga crinitaPhyllophaga crinitaDamages trees, gardens or crops
European Rose ChaferCetonia aurata
Mediterranean Spotted ChaferOxythyrea funestaDamages trees, gardens or crops
Oriental BeetleExomala orientalisDamages trees, gardens or cropsSources
- Wikipedia: https://en.wikipedia.org/wiki/Ten-lined_June_beetle
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-22 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.