Fecal shield

[5] When the shield is carried on the tip of the abdomen, it is secured to a double-lobed, spine-like process called the caudal furca,[6] which is also known as the "anal fork".

[7] The larva constructs the shield by maneuvering its "muscular telescopic and highly protrusible anus",[8] or "anal turret", which is positioned dorsally, on the back.

In the species Hemisphaerota cyanea, the larva constructs a shield which may be more descriptively called a "fecal thatch", because it is woven from narrow, coiled strands of frass.

[9] In some species of the subfamily Chrysomelinae, the female adult coats each of her eggs with feces, and when the larva emerges, it uses this ready-made fecal casing as the base of its shield, adding to it as it grows.

For example, the larva of the tortoise beetle Plagiometriona clavata obtains chemical compounds from its diet of bittersweet (Solanum dulcamara), excretes them, and incorporates them into its shield, where they repel the predatory ant Formica subsericea.

Experiments with several larvae of genus Cassida that feed on volatile-rich tansy show that their shields attract the predatory ant Myrmica rubra.

[10] Another possible function of the fecal shield may include protection of the larva from environmental conditions such as ultraviolet radiation, desiccation, wind, and rain.