Anthrax argyropygus

Distinguished from other Anthrax species by the silvery or argent coloration of the posterior abdomen (the 'argyropygus' or silver-rumped characteristic). Wing venation patterns, particularly the location of the r-m vein, may be used to distinguish Anthrax from related genera such as Systoechus. Adults are active in spring, which may help separate from fall-active species in other genera. Final identification typically requires examination of genitalia or expert confirmation.

Adults frequent meadows and open areas with abundant flowering plants. Larval habitat is dependent on host availability, typically associated with ground-nesting insects in sandy or well-drained soils.

Distribution records are limited in the provided sources. The species has been documented in North America based on iNaturalist observations (626 records), but specific range boundaries are not detailed in available literature.

Adults are active in spring. This seasonal pattern distinguishes Anthrax species from some related genera such as Systoechus, which tend to be active in fall.

Adults feed on nectar from flowers using their elongated proboscis. Larvae are parasitoids; specific hosts for A. argyropygus are not documented in the provided sources, but congeners attack larvae of tiger beetles (Cicindelidae) and solitary bees (Halictidae, Colletidae, Andrenidae).

Complete metamorphosis with egg, larval, pupal, and adult stages. Females deposit eggs near or in host burrows. Larvae attach externally to host larvae and feed as ectoparasitoids, eventually killing the host. Specific details for A. argyropygus are not documented; the life cycle is inferred from congeneric species.

Adults are rapid, agile fliers often mistaken for bees due to their hairy appearance and hovering flight near flowers. They perform pre-flight warm-up by rapidly fluttering wings. Females exhibit host-following behavior, tracking solitary bees back to their nests to deposit eggs.

Adults function as pollinators through incidental pollen transfer on their hairy bodies while feeding on nectar. Larvae act as parasitoids, potentially regulating populations of ground-nesting insects. The species contributes to food web complexity in meadow and grassland ecosystems.

Adults provide pollination services. No direct economic impact is documented; the species is not known to be a pest. The bee-mimicking appearance may cause temporary confusion with stinging insects, but bee flies are harmless to humans.

• Bombylius majorAlso a bee fly with long proboscis and bee-mimicking appearance, but lacks the silvery abdominal coloration of A. argyropygus and is generally larger.
• Systoechus spp.Similar bee flies distinguished by wing venation (position of r-m vein) and typically fall-active rather than spring-active.
• Anthrax georgicusCongener with similar parasitoid lifestyle on tiger beetles, but differs in abdominal coloration and specific host associations.

Frequently mistaken for bees due to hairy appearance and flower-visiting behavior; the single pair of wings and lack of a constricted waist distinguish bee flies from true Hymenoptera.

• bee fly
• parasitoid
• pollinator
• mimicry
• spring-active

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life
• Bombyliidae | Beetles In The Bush | Page 2
• ID Challenge #11 | Beetles In The Bush
• Ground nesting bees beware of the bee fly: Bombyliidae — Bug of the Week
• Danger afoot for ground nesting bees: Look out for bee flies, Bombyliidae — Bug of the Week
• Bug Eric: The Stable Fly