P. tetronycha is also a smaller moth with the wingspan of the adults of this species being between 29 and 33 mm.

For the females of P. tetronycha, their ovipositor (the tubular organ through which the female moth lays her eggs) is lacking the spiny hair like structures that are present on the ovipositor of P. comma.

The adults of this species are on the wing from September to March and are attracted to light.

For the females of P. tetronycha, their ovipositor (the tubular organ through which the female moth lays her eggs) is lacking the spiny hair like structures that are present on the ovipositor of P.

It is known that this species has been reared on piripiri (Acaena anserinifolia) as well as Poa cita.