Scales are present on the bodies of various insects. A notable example are the Lepidoptera, the insect order comprising moths and butterflies, which have scales on their wings and on the head, parts of the thorax and abdomen, and parts of the genitalia. The name is derived from Ancient Greek λεπίδος (scale) and πτερόν (wing).

The Trichoptera (caddisflies) which are a sister group of the Lepidoptera have scales, but also possess caudal cerci on the abdomen, a feature absent in the Lepidoptera. Beetles of family Dermestidae also commonly have scales. Within the dipteran infraorder Culicomorpha, possession of a scale fringe on the posterior margin of the forewings is a proposed synapomorphy of Corethrellidae, Chaoboridae and Culicidae.

Many Zygentoma and Archaeognatha have scales on their bodies, whose iridescent appearance gives certain Zygentoma the common name of silverfish.

The morphology of lepidopteran scales has been studied by Downey & Allyn (1975) and scales have been classified into three groups, namely:

Primitive moths (non-Glossata and Eriocranidae) have 'solid' scales which are imperforate, i.e., they lack a lumen.

As per Scoble (2005):

Morphologically, scales are macrotrichia, and thus homologous with the large hairs (and scales) that cover the wings of Trichoptera (caddisflies).

Though there is great diversity in scale form, they are structured similarly. The body or 'blade' of a typical scale consists of an upper and lower lamina. The surface of the lower lamina is smooth whereas the structure of the upper lamina is structured and intricate. Scales are attached to the substrate by a stalk or 'pedicel'. The scales cling somewhat loosely to the wing and come off easily without harming the insect.