Eristalis transversa

(Wiedemann, 1830)

Transverse-banded Drone Fly, Transverse Flower Fly

Eristalis transversa is a hoverfly in the Syrphidae, first described by Wiedemann in 1830. are mimics, displaying of stinging Hymenoptera. The is common in eastern North America and is frequently observed visiting flowers for nectar and pollen. Like other Eristalis species, adults are important , though specific larval for this species has not been documented.

Eristalis transversa by (c) Judy Gallagher, some rights reserved (CC BY). Used under a CC-BY license.Eristalis transversa by (c) Judy Gallagher, some rights reserved (CC BY). Used under a CC-BY license.Eristalis transversa by no rights reserved, uploaded by Michael Mulqueen. Used under a CC0 license.

Pronunciation

How to pronounce Eristalis transversa: /ɛrɪˈstalɪs trænˈsvɜrsə/

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Identification

Distinguished from similar Eristalis by the three grayish olive transverse bands on the thoracic notum. The abdominal pattern of yellow lateral triangles on the second segment connected to rings, combined with the specific wing venation (spurious , looping R4+5, cross-vein near middle of ), separates it from . The scutellum is bright yellow with narrow black base, unlike some similar species. Male are broadly contiguous; female has distinctive reddish pollinose lower portion.

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Appearance

Small to medium hoverfly, 7–12 mm in length. with pilose on upper half and broadly contiguous in males; black and shining medially with black pile laterally; female frons narrowed above with lower two-thirds reddish pollinose and black pile. reddish yellow; sparsely basally. with dense whitish pollen and pile, stripe and cheeks shining black. opaque black with three grayish olive transverse bands; pleurae with thick yellow pile; scutellum bright yellow with narrow black base. with complex yellow and black pattern: first segment black; second segment with large yellow lateral triangles (smaller in female) and narrow yellow ring; third segment with large lateral spots connected by yellow ring, posterior yellow ring; female with only posterior yellow ring on black background; fourth segment with small anterior yellow spot, posterior yellow ring, and entire shining cross-band before middle (female with only posterior yellow ring). Hypopygium shining black. Wings hyaline with slight yellowish tinge basally; venation includes spurious , looping of R4+5 into r4+5, closed r2+3, anterior cross-vein near middle of . Legs variably colored: typically black with yellow at femoral tips and tibial bases; sometimes half of and base of hind tibiae yellow; rarely front and middle legs almost wholly yellow.

Habitat

frequent flowering plants in various open . Specific larval microhabitat unknown for this , though related Eristalis larvae typically inhabit organic-rich aquatic or semi-aquatic environments.

Distribution

North America east of the Mississippi River; extends into southeastern Canada.

Seasonality

active during warmer months; precise undocumented. Some Eristalis overwinter as adults in sheltered locations such as cave entrances.

Diet

feed on nectar for energy and pollen as protein source for development. Specific larval diet unknown for this ; related Eristalis larvae filter bacteria and organic matter from decomposing substrates.

Life Cycle

Complete with , larva, pupa, and stages. Larval stage undescribed for this . Related Eristalis species have rat-tailed maggot larvae with elongated siphon for respiration in aquatic . Adults of some Eristalis species overwinter in sheltered locations.

Behavior

exhibit hovering characteristic of Syrphidae. Has been observed visiting flowers for feeding. Some Eristalis employ both migratory and resident strategies for winter survival, with individuals either moving south or locally in sheltered microhabitats.

Ecological Role

pollination services; specific role unknown but likely contributes to pollination of flowering plants based on flower-visiting .

Human Relevance

Potential in natural and agricultural settings. No documented negative impacts.

Similar Taxa

  • Eristalis tenaxCommon drone fly with more extensive yellow on and different thoracic banding pattern; distribution includes western North America where E. transversa does not occur
  • Eristalis arbustorumSimilar size and general appearance but lacks distinct three-banded thoracic pattern; abdominal markings differ in arrangement
  • Eristalis dimidiataOverlapping range but with different abdominal pattern and thoracic coloration

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Sources and further reading