Cossina is the name for both a section and subsection of Ditrysia

Ditrysia

The Ditrysia are a natural group or clade of insects in the Lepidopteran order containing both butterflies and moths. They are so named because the female has two distinct sexual openings: one for mating, and the other for laying eggs .About 98% of described species of Lepidoptera belong to Ditrysia...

n insects in order containing both butterflies

Butterfly

A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

 and moth

Moth

A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...

s having a dorsal heart vessel. The section named cossina contains 2 subsections: one also named cossina (containing mostly smaller moths) having pupae with dorsal spines; and subsection Bombycina (containing generally larger sized moths and butterflies) having spineless pupae.

Sources

• Capinera, John, editor (2008), Encyclopedia of Entomology, 2nd ed., Springer Verlag, New York.