Oedoparena minor is a small (wing length 4.0-6.4) coastal fly

Fly

True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...

 from the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Dryomyzidae.

Ecology

The ecology of this species is little known, Adults have been reared from Pupa

Pupa

A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...

 found in the empty shells of dead barnacle

Barnacle

A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile suspension feeders, and have...

s. This is not unlike the life style of a north American speies Oedoparena glauca

Oedoparena glauca

Oedoparena glauca is a common coastal fly from the family Dryomyzidae. It is the only known dipterous predator of barnacles.-Distribution:This is a Nearctic fly occurring from Central California to Alaska.-Ecology:...

, where the larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e feed on living barnacle, before pupating in a now empty barnical shell and then the adult flies emerge during the morning low tide.