Caterpillars are are brown and thin, resembling twigs. They raise one end of their bodies and stretch outward as if a part of a new branch on a tree. This camouflage affords them some protection form predators like birds and bats. Large Maple Spanworms feed on a variety of trees, including maple. Apple, oak, cheery, willow and poplar are a few. Smaller plants like geraniums, grasses, and sweet fern are also good host plants. This means that adults can be found in a variety of places including hardwood forests, parks, gardens, patios, meadows and orchards. They are active from spring through summer and are common in their vast range.