Calypter

A calypter is either of two posterior lobes of the posterior margin of the forewing of flies between the extreme posterior wing base and the alula, which covers the halteres.
The lower calypter is the proximal calypter (synonyms: squama (of some authors), tegula) and the upper calypter is the distal calypter (synonym: squamula).
Species of the subsection Acalyptratae are noted for lacking calypters.