Bombyliidae

Taxonomy

Order: Diptera
Family: Bombyliidae Latreille, 1802
Common names: bee flies or humbleflies

Background

Bombyliidae is a large diverse family of flies. The adults are strong fliers and hover frequently. They are called bee flies because of their often bee-like resemblance and their flower visitation. Adults generally feed on nectar and pollen, and may be important pollinators. The larval biology is poorly known but the majority seem to be nest parasites of wasps and bees.

How to separate from Asian giant hornet

  • Flies have one set of wings instead of two (the hind wings are reduced to small halteres)
  • The overall shape and apperance is much different from wasps and hornets
  • Flies have sucking mouthparts while wasps and hornets have chewing mouthparts

Distribution

Adult bee flies generally favor sunny conditions and dry, often sandy, or rocky areas. They are often found hovering over flowers or resting on the bare ground in the sun.

The family is found worldwide but the greatest species diversity is found in tropical and arid subtropical regions (Evenhuis and Greathead 2015).

Distribution of Bombyliidae by GBIF: https://www.gbif.org/species/7285

Diagnostic characteristics

  • Adults range in length from 2–40 mm (0.8–1.6 inches).
  • Most adults feed on nectar and pollen and have long proboscises that cannot be retracted. Some species in the subfamily Anthracinae have short mouthparts.
  • Many species may superficially resemble bees, with a compact hairy body.
  • Their heads are round, with a convex face.
  • Male eyes are often holoptic.
  • The antennae are short and pointed.
  • Their legs are long and thin.
  • They have one pair of wings.

Diversity

There are about 800 species of bee flies in 70 genera and 13 subfamilies in North America. Worldwide there are over 5,000 species in 230 genera and 15 subfamilies (Hull 1973).

Host/prey associations

The larval stages are parasitoids of immature stages of other insects, particularly wasps and bees. Other species are known to attack the larvae of beetles, other flies, including tsetse flies, and even moths. Adult bee flies feed on nectar and pollen. Bee flies can affect native bee populations by parasitizing their nests.

Nesting and general behavior

Bee fly larvae are predators or parasitoids of the eggs and larvae of other insects. Adult female bee flies deposit their eggs near potential hosts, such as wasp or solitary bee nests. The larva makes its way to the nest where it will feed on the stored provisions and the host's egg or larva. When the bee fly larva is fully grown, it pupates and remains in the nest until next spring. Although some bee flies are host-specific, many species will parasitize a variety of hosts (Yeates and Greathead 2008).

<p><em>Bombylius major</em>; photo by drippingspringstransplant, iNaturalist</p>
<p><em>Exoprosopa fascipennis</em>; photo by Judy Gallagher, Flickr</p>
<p><em>Bombylius major</em>; photo by Michael Knapp, iNaturalist</p>
<p><em>Exoprosopa</em> sp.; photo by Patrick Alexander, Flickr</p>
<p><em>Bombylius major</em>; photo by Anne, iNaturalist</p>