acalyptrate
adj. C2 Proficiency aca·lyp·trate
adj. describing a type of fly that does not have a special structure on its face called a calypter. These flies are usually small and have a different body shape than other flies.
adj. relating to a suborder of flies (Nematocera) that lack the calypters, which are the small, shield-like structures covering the base of the wings. Typically used in entomological classification.
The acalyptrate fly is much smaller than the housefly.
Entomologists often distinguish between acalyptrate and calyptrate flies based on the presence or absence of these wing covers.
While calyptrate flies are generally larger and more robust, acalyptrate species tend to be delicate and are often found in damp environments where they feed on decaying organic matter.