The larvae have 8 instar stages and the size of the caterpillars can be between 1.68 mm for the newly hatched larvae and up to 30 mm for the adult larvae (Grobler 1955). The differences between instars are not very apparent. All instars have wart like protrusions from which hair/setae sprout. They all have a very hairy appearance. The hair of the first instar is a drab brown-grey colour and the last instar has black poisonous setae and long white setae. The adult larva has a maroon coloured head and can have an orange dorso-median stripe. The poisonous urticating’s hairs are 0.07 – 0.2 mm in length and cause dermatitis in humans. Variation in colouring of the larvae are known and they can vary from yellowish to reddish and from black to white.
The cocoon is spun from brown silk and plant material. It is well camouflaged against the soil surface where they can be found beneath the pine needle mat. Pupae are mahogany red in colour and approximately 10 mm long and 5 mm wide (Grobler 1955).
The moth is yellow in colour and they do not feed. The moths emerge from the ground and unfold their wings in the early morning hours. They fly beneath the trees after sunrise and go higher into the branches by midday where they mate. Females can mate multiple times. The antennae in males are plumose when compared to those of females. Females have a brown tuft of setae on the last few segments of the abdomen. They lay egg masses that are covered by setae mainly on the needles of pine trees.