Nature in Futakuchi
Gastrophysa atrocyanea （Chrysomelidae）
Adults lay their eggs on the back of Rumex japonicus or Rumex acetosa and eat the new leaves at they appear on sorrel starting from March.
Hatched larvae pupate eat the same kinds of leaves and stay in the soil for about 20 days.
Adults that emerged in about a week after pupation will appear on the ground next spring.
They spend the winter in the soil.