The closely related antlions (family Myrmeleontidae) have short, weakly clubbed antennae, smaller eyes, and reticulate wing venation.

The sole exception is the Brazilian Albardia furcata, the only living member of the subfamily Albardiinae, which has short antennae, but these are strongly clubbed (compared to myrmeleontids), and its wing venation is reticulate, typical of ascalaphids.

[6] The larvae too are predatory, making owlflies important in maintaining a natural ecological balance and helping to control pest insects.

[4] Some New World species such as Haploglenius luteus are able to suddenly reflex a flap on the pronotum, exposing a strongly-contrasting patch of pale colour (white or cream), either as a deimatic display to startle predators,[9] or as heliographic signalling, reflecting sunlight, to attract females.

Owlfly larvae are ambush predators, and sequester themselves at the soil surface, in ground litter, or on vegetation, sometimes covered with debris, and wait for prey, which they seize with their large, toothed mandibles.

[15] In Greek mythology, Ascalaphos was the custodian of the orchard of Hades, god of the underworld; the goddess Demeter transformed him into an owl.

[20] Molecular analysis in 2018 using mitochondrial rRNA and mitogenomic data also placed the Ascalaphidae as sister to the Myrmeleontidae as the most advanced groups within the Neuroptera.

Myrmeleontoidea Machado et al 2018 proposes a classification below family level, into tribes (names ending with –ini):[20] Groups formerly considered part of "Myrmeleontidae" are underscored and marked "Myrm."

Haplogleniini Ascalaphini Myrmeleontinae Dendroleontinae Nemoleontinae Jones 2019 presents a total-evidence phylogeny, preferring to classify only to family level:[1] Myrmeleontidae Palparidae "Myrm."