the third instar has bands of spines completely around the spine at segments 2 through 9. segment 10 has a band of spines, but there is generally a small area on the front that is not complete. there are five or six irregular rows on the back of segment 11. segment 12 is usually smooth on its dorsal surface. the posterior spiracles are relatively large and darkly pigmented; the anterior spiracles (generally six to eight) have relatively large branches. the cephaloskeleton is also large and darkly colored.