Larvae have a dark-gray to brownish-black background body color, highlighted by broad, pale- blue lines and thin, broken yellow lines extending along each side. On the dorsum of each abdominal segment is a distinct, whitish keyhole or shoeprint-shaped marking. Larvae are also somewhat hairy, the setae being fine, whitish in color, and sparsely distributed. Mature larvae are 2 to 2.5 in. (50 to 64 mm) in length. Pupation occurs in a pale- yellow, loosely spun silken cocoon. The stout-bodied adult moths are tan to buff-brown in color, with two darker, thin parallel lines extending across the mid-portion of each forewing, the area between often being dark and appearing as a single, broad, dark band. The wingspread ranges from 1 to 1 3/4 in. (25-45 mm). Eggs occur in masses of 100 to 350, forming bands up to 1 in. (25 mm) in length that encircle small diameter twigs. Egg masses are coated with a dark-brown, frothy, cement-like substance called spumaline. View the forest tent caterpillar moth here!