The larvae grow to 7 mm (0.28 in) in length, are reddish brown in colour and covered with bristles.

The larval form feeds on natural fibres, damaging carpets, furniture and clothing.

Attagenus unicolor undergoes complete metamorphosis, which has four life stages: Egg, larvae, pupae and adult.

If no food source can be found, the female will lay them in dark undisturbed locations where the larvae can feed on carpeting or clothing.

Pupae are cream white but quickly turn yellow and darken with age.