Syrphus

Fabricius, 1775

Common Flower Flies

Species Guides

7

Syrphus is a of hoverflies in the Syrphidae, characterized by distinctive calypter . The genus is distinguished from other Syrphini by long hairs on the upper surface of the lower lobe of the calypter, a unique diagnostic feature. are common flower visitors and , while larvae are primarily . The genus includes approximately 20 described distributed across the Holarctic region, with several species occurring in North America and Europe.

Syrphus torvus by (c) Alexis Lours, some rights reserved (CC BY), uploaded by Alexis Lours. Used under a CC-BY license.Syrphus torvus by (c) Kostas Zontanos, some rights reserved (CC BY), uploaded by Kostas Zontanos. Used under a CC-BY license.Syrphus torvus by (c) Michael Knapp, some rights reserved (CC BY), uploaded by Michael Knapp. Used under a CC-BY license.

Pronunciation

How to pronounce Syrphus: //ˈsɪrfəs//

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Identification

Distinguished from all other in tribe Syrphini by the presence of long hairs on the upper surface of the lower lobe of the calypter (in addition to the rear marginal hairs present in most Syrphini). typically exhibit - or -like coloration with yellow and black abdominal banding. Males have that meet at the top of the ; female eyes are separated. One pair of wings distinguishes them from Hymenoptera.

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Habitat

Found in diverse environments including gardens, meadows, forests, and agricultural areas. Associated with flowering vegetation where forage for nectar and pollen.

Distribution

Holarctic distribution. Present in North America (including western North America where S. intricatus and S. sonorensis occur), Europe, and Asia. Syrphus sexmaculatus recorded in North America. S. opinator documented in the Greater Yellowstone and California.

Seasonality

most conspicuous in spring and fall when peak. Active during daylight hours; observed warming muscles in early morning.

Diet

Larvae are obligate . feed on nectar and pollen from flowers; possess an extendable tipped with a sponge-like for liquid feeding.

Life Cycle

Complete with four stages: , larva, pupa, . Female lays eggs in or near colonies. Larvae pass through three instars before . Pupa is a convex pear-shaped structure attached to leaves or stems. Development time from egg to adult approximately 18–19 days under laboratory conditions at 22–24°C.

Behavior

exhibit characteristic hovering . Larvae engage in active prey searching with 'casting' —elevating and extending body segments above the substrate to locate aphids. Larval movement rate decreases and casting frequency increases after encounters. S. ribesii shows higher capture and shorter handling time on Aphis fabae compared to some sympatric syrphid .

Ecological Role

Important agents: larval on aphids suppresses pest in agricultural and natural . serve as of various flowering plants.

Human Relevance

Beneficial insects in gardens and agriculture; larvae control pests without chemical intervention. Frequently mistaken for bees or due to mimetic coloration.

Similar Taxa

  • EpistropheBoth in tribe Syrphini with similar coloration; distinguished by calypter hair pattern—Syrphus uniquely has long hairs on upper surface of lower calypter lobe
  • MelanostomaLarval with overlapping use; S. ribesii shows higher prey capture and more extensive casting than M. scalare
  • EupeodesSimilar -mimetic appearance and flower-visiting habits; separated by calypter and wing venation details

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