Original: It is believed that the name '' butterfly '' originated from a member of this family â '' the Brimstone Gonepteryx rhamni â '' which was called the '' butter-coloured fly '' by early British naturalists .
Simplified: It is believed that the name '' butterfly '' originated from a member of this family , the Brimstone Gonepteryx rhamni . It was called the '' butter-coloured fly '' by early British naturalists .