Cecropia Moth Caterpillar
a green cecropia moth caterpillar with yellow and blue protuberances on a brown stem
Michael Hodge / Wikimedia Commons / CC BY 2.0
These plump green bruisers, found throughout the U.S. and Canada, grow to be over four inches long.13 As they pack on weight, they turn from black to bright sea green to iridescent bluish green (like the one pictured here). Most impressive, though, are their many blue, orange, and yellow protuberances (tubercles) wielding black spines. They may look scary, but it's all for show.
Cecropia moth caterpillars don't sting or cause harm to humans. They spend their time eating leaves all summer long before they make themselves a cocoon to spend the winter. When caterpillars first hatch, they are black, but with successive molts they turn yellow and eventually green.14 Come spring, they morph into North America's largest moth and one of its most spectacular species.
Adult moths, who don't eat at all, sport reddish-orange bodies and brown wings marked with bands of orange, tan, and white, with white crescent-shaped marks and eye spots.