Bug FAQGreen Dock Beetle
Gastrophysa viridula · Order: Coleoptera · Family: Chrysomelidae
Also called: Green Dock Leaf Beetle
The green dock beetle is a small metallic green beetle, males about 4 mm long and females about 7 mm. It lives in heathlands, forests, meadows and gardens where dock plants grow and feeds mainly on dock and green sorrel. Adults breed from March to October, producing 2 to 4 generations per year, with the last generation hibernating as adults.
Source: Wikipedia
How to recognize it
Both sexes shine metallic green, showing gold, blue, purple, violet or red tones depending on the light. Their legs are also metallic green and robust.
Source: Wikipedia
Size
Males are about 4 mm long, while females reach about 7 mm.
Source: Wikipedia
What it eats
Adults mainly eat dock and green sorrel, and may occasionally feed on other plants in the Polygonaceae, Brassicaceae, Violaceae and Boraginaceae families. Larvae can only complete development on Rumex species.
Source: Wikipedia
Life cycle
Breeding runs from March through October. There are 2 to 4 broods each year, and the final brood hibernates as an adult.
Source: Wikipedia
When you see it
The active breeding season spans March to October.
Source: Wikipedia
Lookalikes
In North America a similar species, Gastrophysa cyanea, is also called the green dock beetle.
Source: Wikipedia
Where it is found in the US
Recorded in 2 of 51 states and DC. Most records: Nebraska, Colorado.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
More photos
Questions people ask
How can I recognize a green dock beetle?
Look for a small metallic green beetle, 4 mm (male) or 7 mm (female), with legs that also shine green and may show gold, blue, purple, violet or red hues in the light.
Source: Wikipedia
What plants do green dock beetles eat?
They mainly feed on dock and green sorrel, and may occasionally nibble other plants in the Polygonaceae, Brassicaceae, Violaceae and Boraginaceae families.
Source: Wikipedia
When are green dock beetles active?
Adults are active and breeding from March through October, producing several generations each year.
Source: Wikipedia
Are there similar beetles I might confuse with this one?
Yes, the North American species Gastrophysa cyanea is also called the green dock beetle and looks similar.
Source: Wikipedia
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/Gastrophysa_viridula
Look it up elsewhere: GBIF · iNaturalist · BugGuide · Wikipedia
Text written 2026-10-24 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.