What is the largest butterfly species by wingspan?

Queen Alexandra’s birdwing is the largest butterfly species by wingspan.

This spectacular butterfly, Ornithoptera alexandrae, is native to the rainforests of Papua New Guinea. Females are considerably larger than males and can reach wingspans of about 28 centimetres, making the female the usual basis for the species’ size record.

The species was named for Queen Alexandra, wife of King Edward VII. British naturalist Albert Stewart Meek collected the first known specimen in 1906, and the butterfly was formally described soon afterward.

A common mix-up is calling the atlas moth the largest butterfly. The atlas moth is a moth, not a butterfly, and has a much larger wing area. Queen Alexandra’s birdwing is also not the same species as the somewhat smaller Goliath birdwing. Habitat loss and collection have made this birdwing highly threatened.