Tulip-tree Silkmoths are members of a family known for its striking good looks as well as mammoth size. The green Luna Moth, Cecropia Moth, and Promethea Moth are all relatives. The similarity between the Promethea Moth and the Tulip-tree is remarkable. They look so alike, it is possible that the ones pictured are actually the other. They are both in the same genus, and both show a slight color difference between the sexes (dimorphism).