They are found almost exclusively in the Neotropical realm, although there is one record from extreme southern Texas, United States.

No true fossils are known, although there are some specimens in Colombian copal, of unknown (but likely relatively recent) age.

[5][6][7][8][9][10][11] Some attack their hosts while flying, darting down to lay their eggs; others land, curl their ovipositor under their bodies and rush their hosts on foot (as in M. acoma, see photo); a few carefully land on their host and stealthily inject their egg.

The holotype specimen was lost in a fire at the Hungarian National Museum.

The effects of Melaloncha parasitism on commercial beekeeping, including efforts to keep native tropical stingless bees (meliponiculture), and the scale of financial losses due to these flies has not been studied.