One of its constituent families, the Anisopodidae, is the presumed sister taxon to the entire suborder Brachycera.

[1] Several of the remaining families in the infraorder (those shown without common names) are former subfamilies of the Mycetophilidae, which has been recently[when?]

Most representatives of the Bibionomorpha are saprophages or fungivores as larvae with the Cecidomyiidae being predominantly gall-formers.

Some sciarids are common indoor pests, developing large populations in potting soil that has become moldy from overwatering.

The larvae of the Bibionidae sometimes migrate in large, snake-like masses to minimize dehydration while seeking a new feeding site.