Unidentified Saturniidae moth caterpillar The Saturniidae are moths medium to very large in size, commonly referred to as Giant Silkworm and Royal Moths; this family includes the largest moths in North America. Adults have a wingspan of 3 to Moth Caterpillar, Trees And Shrubs, Weird And Wonderful, North America, Insects, Butterfly, Night Crawlers, Nature, Butterflies