The Bombyliidae are a large family of flies comprising hundreds of genera, but the life cycles of most species are known poorly, or not at all.

The adult females usually deposit eggs in the vicinity of possible hosts, quite often in the burrows of beetles or wasps/solitary bees.

However, most species do not often appear in abundance, and compared to other major groups of pollinators they are much less likely to visit flowering plants in urban parks or suburban gardens.

In other species patches of flattened hairs occur that can act as silvery, gilded or copper-tone reflecting mirrors; these perhaps serve as visual signals in conspecific mate/rival recognition, or perhaps imitate reflecting surface particles on bare soils with high content of materials like quartz, mica or pyrite.

The alula are well developed and in the rest position the wings are kept open and horizontal in a V shape revealing the sides of the abdomen.

The abdomen is generally short and wide, subglobose-shaped, cylindrical, or conical, composed of six to eight apparent urites.

The wing venation, although variable within the family, has some common characteristics that can be summarized basically in the particular morphology of the branches of the radial sector and the reduction of the forking of the media.

The cubital and anal veins are complete and end separately on the margin or converge joining for a short distance Consequently, the cell cup may be open or closed.

Unlike the majority of glyciphagous dipterans, the bee flies feed on pollen (from which they meet their protein requirements).

As with hoverflies, bee flies are capable of sudden acceleration or deceleration, all but momentum-free high-speed changes of direction, superb control of position while hovering in mid-air, as well as a characteristically cautious approach of a possible feeding or landing site.

Bombyliids are often recognizable by their stocky shapes, by their hovering behavior, and for the particular length of their mouthparts and/or legs as they lean forward into flowers.

Unlike hoverflies, which settle on the flower as do bees and other pollinating insects, those bee fly species which have a long proboscis generally feed while continuing to hover in the air, rather like Sphingidae, or while touching the flower with their front legs to stabilize their position - without fully landing or ceasing oscillation of the wings.

Species with shorter proboscis do land and walk on flower heads, however, and can be much harder to distinguish from hoverflies in the field.

As noted, many bee fly species spend regular time intervals at rest on or near the ground, while hoverflies hardly ever do so.

Close observation is often easier with feeding individuals than with flies on the ground, as the latter are especially quick to take flight at the first sight of moving silhouettes or approaching shadows.

[5] Males often seek out smaller or larger clearings on the ground, presumably in vicinity of flowering plants or host nesting habitats that are likely attractive to females.

Gravid females seek out nesting habitats of hosts, and can spend many minutes inspecting for example entrances of smaller burrows in soil.

If a burrow passes scrutiny then the bee fly may proceed to land and insert its posterior abdomen into the soil, laying one or more eggs at the edge or in close vicinity to it.

This remarkable behavior has earned such species the colloquial name of Bomber flies, it can be seen in Roy Kleuker's online video clip in YouTube.

After these revisions, the bee flies sensu stricto have a greater morphological homogeneity, but the monophyly of the family still remains dubious.

[15] Phylogenetic analysis of CAD and 28S rDNA gene sequences supports monophyly of only eight subfamilies out of fifteen included in the study, with the Bombyliinae resolving as a highly polyphyletic group.