Dock-beetle
Guides
Gastrophysa cyanea
green dock beetle, blue dock beetle
Gastrophysa cyanea is a small leaf beetle in the family Chrysomelidae, measuring 4-5 mm with metallic green coloration that may shift to metallic blue in pinned specimens. The species is found across North America and is strongly associated with dock plants (Rumex species), particularly curly dock. Females develop conspicuously swollen abdomens prior to egg laying, providing a reliable diagnostic feature. The species emerges in spring and has been the subject of behavioral studies examining host plant recognition.