Bug FAQThistle Tortoise Beetle
Cassida rubiginosa · Order: Coleoptera · Family: Chrysomelidae
Also called: Green Thistle Beetle
The thistle tortoise beetle is a small, 6 to 8 mm beetle with a rounded green back, sometimes showing a tiny dark spot near the scutellum. It lives where thistles grow to fields, pastures, orchards, meadows and farmland to across a range that includes Great Britain, Siberia, and much of Europe from Fennoscandia to Greece and Spain. Adults eat thistles and other members of the aster family and may also sip pollen from buttercups and ox-eye daisies; larvae were first described in 1931 and later documented in 2004.
Source: Wikipedia
How to recognize it
Its back is green and rounded, sometimes with a small dark triangular spot near the scutellum.
Source: Wikipedia
Size
Adults measure about 6 to 8 mm long.
Source: Wikipedia
Where it lives
Found in places with abundant thistles such as fields, pastures, orchards, meadows and farmland. Its range includes Great Britain and Siberia.
Source: Wikipedia
What it eats
Feeds on various Asteraceae plants, especially thistles. Adults may also consume pollen from buttercups and ox-eye daisies.
Source: Wikipedia
Life cycle
The mature larva was first documented in 1931. The instar larva was first recorded in 2004.
Source: Wikipedia
Where it comes from
First recorded in 1902 in Lévis, Quebec. In Europe it occurs from Fennoscandia down to Greece and Spain.
Source: Wikipedia
Where it is found in the US
Recorded in 33 of 51 states and DC. Most records: Pennsylvania, Ohio, Michigan, New York, Maryland, New Jersey, Colorado, Wisconsin.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: introduced in Canada; introduced in United States. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Same family (Chrysomelidae)
Spotted Cucumber BeetleDiabrotica undecimpunctataDamages trees, gardens or crops
Bean WeevilAcanthoscelides obtectusDamages trees, gardens or crops
Cowpea WeevilCallosobruchus maculatusDamages trees, gardens or crops
Swamp Milkweed Leaf BeetleLabidomera clivicollisDamages trees, gardens or crops
Alder Leaf BeetleAgelastica alniDamages trees, gardens or crops
Dogbane Leaf BeetleChrysochus auratusSources
- Wikipedia: https://en.wikipedia.org/wiki/Thistle_tortoise_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.