These flies lay their eggs and develop as larvae in an extremely wide range of organic materials, including carrion, eggs, decaying plants, and rotting fungi. They occasionally infect the gastrointestinal tract, urinary tract, as well as incompletely healed wounds of humans, causing a condition known as myiasis. In tropical America, they invade the nests of stingless bees being kept for honey production, possibly after primary invasion by another phorid fly, Pseudohypocera kerteszi (Enderlein). They have even been reared from some bizarre media, such as paint and boot polish.

The main notoriety of these flies, however, is for their persistent infestation of all types of living animal cultures, including those of cockroaches, crickets, tarantulas, hermit crabs, lizards, and snakes. They are found in nearly every insect zoo in the world, where the larvae feed on dead, dying, or injured animals. Under crowded conditions they can also attack living animals, causing their death. 

The ease of culture of these flies has made them attractive model organisms for genetic research, similar to Drosophila melanogaster Meigen. There are three pairs of chromosomes present, and some research has been done on sex determination in M. scalaris.