Volucella

Geoffroy, 1762

hover-flies, flower flies

Species Guides

Volucella arctica(Arctic Swiftwing)
Volucella evecta(Eastern Swiftwing)
Volucella facialis(Yellow-faced Swiftwing)

Volucella is a of large, broad-bodied hoverflies in the Syrphidae. These flies are notable for their of stinging Hymenoptera—particularly bumble bees and —which provides protection from . are regular flower visitors that feed on nectar, while larvae develop as in the nests of social bees and , functioning as and predators of larvae. The genus exhibits strong migratory and males are often territorial.

Volucella by (c) Michael Knapp, some rights reserved (CC BY), uploaded by Michael Knapp. Used under a CC-BY license.

Volucella isabellina by the Smithsonian. Used under a CC0 license.

Volucella facialis by the Smithsonian. Used under a CC0 license.

Pronunciation

How to pronounce Volucella: //vɔˈluː.sɛl.lə//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from bees by single pair of wings (versus two pairs in Hymenoptera) and short, (versus longer, elbowed antennae in bees). The extended, downward-projecting and plumose are diagnostic for the . Volucella zonaria can be separated from V. inanis by chestnut-colored second tergite and broad black abdominal markings. In North America, Volucella bombylans complex is the only recognized , though evidence suggests this represents a cryptic .

Images

Appearance

Large, broad-bodied flies with robust builds. Distinctive (feathery) on the . extended downward, creating a pronounced facial projection. Many exhibit striking yellow and black abdominal banding that mimics the coloration of bumble bees or . possess a single pair of wings (characteristic of Diptera) with the hindwings reduced to small knob-like .

Habitat

frequent flowering plants in gardens, meadows, and woodland edges. Urban and suburban areas are commonly occupied, particularly by migratory . Larval is restricted to the nests of social bees and , where they inhabit detritus accumulations at nest bases.

Distribution

Widespread across the Palaearctic region. Volucella zonaria colonized the United Kingdom in the late 1930s (initially in London), spreading to become frequent across England and Wales and reaching central Scotland. North American records represent Volucella bombylans complex, primarily distributed in western regions. Multiple documented from the Pothwar region of Punjab, Pakistan.

Seasonality

active from May through November in temperate regions, with peak abundance typically in August. Presence strongly correlated with abundance of in previous year.

Diet

feed on nectar from flowers; Volucella zonaria shows particular preference for Buddleja ( bush). Larvae scavenge debris and consume larvae within and nests.

Host Associations

Bombus - larvae inhabit nests
Vespula vulgaris - larvae inhabit common nests
Vespula germanica - larvae inhabit German wasp nests

Life Cycle

Larvae develop within active nests of social bees and , where they function as and on larvae. occurs within the host nest. emerge and disperse to feed on floral nectar. Specific details of deposition and complete developmental duration are not well documented.

Behavior

Strongly migratory, with capable of long-distance . Males frequently exhibit territorial , defending favorable perching sites or floral resources. often observed sunning on leaves. of stinging Hymenoptera reduces risk. Volucella zonaria shows correlation between population levels and preceding summer abundance.

Ecological Role

contribute to pollination through regular flower visitation. Larvae function as nest associates () of social Hymenoptera, with mixed - that may influence nest dynamics. The represents a classic example of in insect .

Human Relevance

Beneficial as in gardens and agricultural settings. Larval association with nests occasionally brings them to human attention, though they do not attack healthy colonies. Some , particularly V. zonaria, have expanded range in response to urbanization and anthropogenic activity.

Similar Taxa

CopestylumFormerly included some now placed in Copestylum (e.g., C. mexicanum, the Mexican cactus fly); distinguished by larval in rotting cactus tissue rather than social insect nests
BombusBumble bees are the primary mimicry models; distinguished by two pairs of wings, longer elbowed , and ability to sting
Vespa crabroEuropean hornet is the mimicry model for V. zonaria; distinguished by larger size, two pairs of wings, and potent sting

More Details

Mimicry and visual specializations

Volucella pellucens males possess a specialized frontal- retinal region termed the 'love spot,' containing photoreceptors with superior temporal resolution adapted for mate recognition and pursuit during high-speed chasing . This represents a morphological and physiological for binocular vision in mate location.

Taxonomic complexity

North American assigned to Volucella bombylans likely represent a cryptic based on evidence, though currently treated as a single valid . The has undergone taxonomic revision with some former members (e.g., Mexican cactus fly) reassigned to Copestylum.