The wings are greyish brown and marked with fine dark cross lines.

The caterpillars feed in the trunks and branches of a wide variety of trees (see list below), taking three to five years to mature.

The caterpillar holes can be found low on the stem (maximum 1.0–1.5 m above the ground).

When ready to pupate the caterpillar leaves the tree to find a suitable spot.

[1] Pliny reported in Natural History that a grub which he gives the name cossus was considered a Roman delicacy after it was fed with flour.