Wallace's golden birdwing butterfly

Description

The upperside wings are black and have a yellow costal band.There is a clearly visible long oval sex brand (of androconial scales) in the black area.The underside is black marked with lines of green chevrons.The upperside hindwings are yellow and the underside is green,yellow towards the costa.The veins are black and there is a submarginal row of black spots.The head and thorax are brown and the abdomen is yellow.typical of birdwing butterflies,Ornithoptera croesus is strongly sexually dimorphic.Females are larger than males and have brown wings marked with lines of yellow chevrons.