Hoverfly

For the helicopter, see Sikorsky R-4.

Syrphidae
Temporal range: Eocene–Present
Sixteen different species of hoverflies
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Section: Aschiza
Superfamily: Syrphoidea
Family: Syrphidae
Latreille, 1802
Subfamilies

Hoverflies, also called flower flies or syrphids, make up the insect family Syrphidae. As their common name suggests, they are often seen hovering or nectaring at flowers; the adults of many species feed mainly on nectar and pollen, while the larvae (maggots) eat a wide range of foods. In some species, the larvae are saprotrophs specifically Detritivores [1] eating decaying plant and animal matter in the soil or in ponds and streams. In other species, the larvae are insectivores, preying on aphids, thrips, and other plant-sucking insects.

Insects such as aphids are considered crop pests, and therefore the aphid-eating larvae of some hoverflies are economically and ecologically important. The larvae are potential agents for use in biological control; while the adults are pollinators.

About 6,000 species in 200 genera have been described. Hoverflies are common throughout the world and can be found on all continents except Antarctica. Hoverflies are harmless to most mammals, though many species are mimics of stinging wasps and bees, a mimicry which may serve to ward off predators.

Hoverfly hovering behavior is unlike that of hummingbirds since they do not feed in midair. Hovering in general may be a means of finding a food source; male hovering is often a territorial display seeking females,[2] while female hovering serves to inspect ovipositing sites. [3][4][5]

A hoverfly on flowers in Japan

Description

The size of hoverflies varies depending on the species.[6] For example Paragus tibialis[7][8][9] is 3–5 mm (1⁄8–13⁄64 in) long while Criorhina nigriventris is 13.6–20.6 mm (17⁄32–13⁄16 in) long.[10] Some, such as members of the genus Baccha, are small, elongated, and slender, while others, such as members of Criorhina, are large, hairy, and yellow and black. As members of the Diptera, all hoverflies have a single functional pair of wings, with the hind wings reduced to balancing organs.[11] Many species are brightly colored, with spots, stripes, and bands of yellow or brown covering their bodies.[11] Due to this coloration, they are often mistaken both by insect-eating birds and by humans for wasps or bees; they exhibit Batesian mimicry. Despite this, hoverflies are harmless to humans.[6] Drone flies, Eristalis tenax, are an example of a species of hoverfly who exhibit Batesian mimicry.[12]

With a few exceptions,[13] Hoverflies are distinguished from other flies by having a spurious vein, located parallel to their fourth longitudinal wing vein.[6] Adults feed mainly on nectar and pollen.[11] Many species also hover around flowers, lending to their common name.[6]

Bee flies of the family Bombyliidae often mimic Hymenoptera and hover around flowers, as well, rendering some bombyliid species hard to tell apart from Syrphidae at first glance. Hoverflies can, nevertheless, be distinguished in the field by anatomical features such as:[citation needed]

  • The legs and mouthparts of hoverflies are usually not particularly long and thin (some bombyliids have a long and needle-like proboscis, many have legs that are noticeably longer and thinner than in similar-sized syrphids)
  • Their facial cuticle often has prominent bulges and/or beak- to knob-like projections (most bee flies have an evenly curved or sloping face).
  • The wings are often clear or have smooth gradients of tinting, and their veins merge posteriorly into a "false edge" that runs parallel to the wing's true rear edge and extends along half or more of the wing length (bombyliid wings lack a "false rear edge" and often have large dark areas with sharp boundaries, or complex patterns of spots).
  • Their abdomens and thoraces often have glossy cuticular body surfaces, abdominal colors are usually mainly due to cuticular pigments (bee flies are usually very hairy, their abdominal colors are almost always due to pigmentation of hairs and not the underlying cuticle).
Their wariness of people is surprisingly low, and their behaviour can be observed up close.

Reproduction and life cycle

Midair mating of Simosyrphus grandicornis

Unlike adults, the maggots of hoverflies feed on a variety of foods; some are saprotrophs, eating decaying plant or animal matter, while others are insectivores, eating aphids, thrips, and other plant-sucking insects.[6][14] Predatory species are beneficial to farmers and gardeners, as aphids destroy crops, and hoverfly maggots are often used in biological control. This includes one of the most common widespread hoverfly species, Episyrphus balteatus, whose larvae feed on aphids. Certain species, such as Merodon equestris or Eumerus tuberculatus, are responsible for pollination.[citation needed]

Hoverfly depositing egg on Epipactis helleborine which has ants farming aphids

An example of a well-known hoverfly maggot is the rat-tailed maggot, of the drone fly, Eristalis tenax. It has a breathing siphon at its rear end, giving it its name.[6] The species lives in stagnant water, such as sewage and lagoons.[15] The maggots also have a commercial use, and are sometimes sold for ice fishing.[16]

An ichneumonid wasp ovipositing inside a hoverfly larva

Very rarely, hoverfly larvae have caused accidental myiasis in humans. This occurs when the larvae are accidentally ingested from contaminated food.[15][17]

Evolution

The oldest known fossils of crown group Syrphidae are from the Eocene aged Florissant Formation, Green River Formation and Baltic amber. The genus Prosyrphus, found in Late Cretaceous (Cenomanian) Burmese amber, appears to represent a stem group to the family.[18]

Distribution and habitat

Hoverflies are a cosmopolitan family found in most biomes, except extreme deserts, tundra at extremely high latitudes, and Antarctica.[19][20] Certain species are more common in certain areas than others; for example, the American hoverfly, Eupeodes americanus, is common in the Nearctic realm, and the common hoverfly, Melangyna viridiceps, is common in the Australasian realm. About 6,000 species and 200 genera are in the family.[21]

While some hoverfly larvae are aquatic and are often found in stagnant water, those of species that prey upon aphids and other plant parasites are usually terrestrial, residing on leaves.[22] Adults are often found near flowers, their principal food source being nectar and pollen.[11] Some species are inquilines; for instance, members of the genus Volucella can be found in bumblebee nests, while members of Microdon are myrmecophiles, found in ant or termite nests.[6] Others can be found in decomposing vegetation.

Pollination

Episyrphus balteatus on a daisy
Eupeodes corollae

Hoverflies are important pollinators of flowering plants in many ecosystems worldwide.[23] Syrphid flies are frequent flower visitors to a wide range of wild plants, as well as agricultural crops, and are often considered the second-most important group of pollinators after wild bees. Relatively little research into fly pollinators has been conducted, compared to bees.[23] Bees are thought to be able to carry a greater volume of pollen on their bodies, but flies may be able to compensate for this by making a greater number of flower visits.

Like many pollinator groups, syrphid flies range from species that take a generalist approach to foraging by visiting a wide range of plant species through those that specialize in a narrow range of plants.[24] Although hoverflies are often considered mainly nonselective pollinators, some hoverflies species are highly selective and carry pollen from one plant species.[25] Cheilosia albitarsis is thought to only visit Ranunculus repens.

Specific flower preferences differ among species, but syrphid fly species have repeatedly been shown to prefer white- and yellow-coloured flowers.[26] Nonvisual flower cues such as olfactory cues also help these flies to find flowers, especially those that are not yellow.[27] Many syrphid fly species have short, unspecialized mouth parts and tend to feed on flowers that are more open as the nectar and pollen can be easily accessed.[28]

Also, a number of interactions occur between orchids and hoverflies. The orchid species Epipactis veratrifolia mimics alarm pheromones of aphids which attracts pollinating hoverflies.[29] Another plant, the slipper orchid in southwest China, also achieves pollination by deceit by exploiting the innate yellow color preference of syrphids.[30]

Systematics

Main article: Genera of Syrphidae

Relationship with humans

Hoverfly nectaring on a small flower bud covered with dew drops.

Adult syrphid flies are pollinators.

Larvae of many hoverfly species prey upon pest insects, including aphids and leafhoppers, which spread some diseases such as curly top, so they are seen in biocontrol as a natural means of reducing levels of pests. Gardeners, therefore, sometimes use companion plants to attract hoverflies. Those reputed to do so include Alyssum spp., Iberis umbellata, statice, buckwheat, chamomile, parsley, and yarrow.[31] Many syrphids, such as Toxomerus marginatus, are attracted to herbivore-induced plant volatiles, and there are commercial formulations of said volatiles, like methyl salicylate, which can be used to attract them for biocontrol purposes.[32] Larvae in the subfamily Eristalinae live in semi-aquatic and aquatic environments, including manure and compost, and can filter and purify water.

Fredrik Sjöberg's [sv] book The Fly Trap concerns his enthusiasm for hoverflies on the island of Runmarö in the Baltic Sea.[33] The island is a hotspot for hoverflies and other insects; Sjöberg has collected 58 species of butterflies there, and (in seven years of hunting) 202 species of hoverflies, including 180 in his garden.[34]

Identification guides

  • Skevington, J.H., et al., 2019. Field Guide to the Flower Flies of Northeastern North America. Princeton University Press ISBN 9780691189406. This book "covers all 413 known syrphid species that occur in or north of Virginia, Kentucky, and Missouri, west to include Iowa, Minnesota, Ontario, and Nunavut, and east to the Atlantic Ocean, including Greenland."
  • Stubbs, A.E. and Falk, S.J. (2002) British Hoverflies An Illustrated Identification Guide. Pub. 1983 with 469 pages, 12 col plates, b/w illus. British Entomological and Natural History Society ISBN 1-899935-05-3. 276 species are described with extensive keys to aid identification. It displays 190 species on colour plates. 2nd edition, pub. 2002, includes new British species and name changes. It includes European species likely to appear in Britain. Additional black and white plates illustrate the male genitalia of the difficult genera Cheilosia and Sphaerophoria.
  • van Veen, M.P. (2004) Hoverflies of Northwest Europe: Identification Keys to the Syrphidae. KNNV Publishing, Utrecht ISBN 9050111998.
  • Miranda G.F.G., Young A.D., Locke M.M., Marshall S.A., Skevington J.H., Thompson F.C. (2013) Key to the Genera of Nearctic Syrphidae. doi:10.3752/cjai.2013.23
  • Bot, S. and Van de Meutter, F. (2023) Hoverflies of Britain and North-west Europe: A photographic guide (Bloomsbury Naturalist). ISBN 978-1-3994-0245-3.

Regional lists

References

  1. ^ Rotheray, G.E. (1993). "Colour Guide to Hoverfly Larvae (Diptera, Syrphidae) in Britain and Europe" (PDF). Dipterists Digest. 9: 155.
  2. ^ Collett, T.S.; Land, M.F. (September 1978). "How hoverflies compute interception courses". Journal of Comparative Physiology. 125 (3). Springer-Verlag: 191–204. doi:10.1007/BF00656597.
  3. ^ Almohamad, Raki; Verheggen, François J.; HaubrugeUniv, Éric (2009). "Searching and oviposition behavior of aphidophagous hoverflies (Diptera: Syrphidae): a review". Biotechnologie, Agronomie, Société et Environnement. 13 (3): 467–481.
  4. ^ Vera Strader. "Hover Flies, a Gardener's Friend" (PDF). University of California Agriculture and Natural Resources.
  5. ^ Peter Chen (December 6, 2023). "Allograpta exotica ovipositing - Allograpta exotica - Female". Bugguide. Iowa State University.
  6. ^ a b c d e f g "hoverfly". Encyclopædia Britannica Online. 2009. Retrieved December 5, 2009.
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  8. ^ Ball, S.G.; Morris, R.K.A. (2000). Provisional atlas of British hoverflies (Diptera, Syrphidae). Monks Wood, UK: Biological Record Centre. pp. 167 pages. ISBN 1-870393-54-6.
  9. ^ Van Veen, M.P. (2004). Hoverflies of Northwest Europe, Identification Keys to the Syrphidae (Hardback). Utrecht: KNNV Publishing. p. 254. ISBN 90-5011-199-8.
  10. ^ Skevington, Jeffrey H. (2019). Field Guide to the Flower Flies of Northeastern North America. ISBN 9780691189406.
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  12. ^ Heal, Jonathan (1979). "Colour patterns of syrphidae:". Heredity. 42 (2). Springer Science and Business Media LLC: 223–236. doi:10.1038/hdy.1979.24. ISSN 0018-067X.
  13. ^ Reemer, Menno (2008). "Surimyia, a new genus of Microdontinae, with notes on Paragodon Thompson, 1969 (Diptera, Syrphidae)" (PDF). Zoologische Mededelingen. 82: 177–188.
  14. ^ Schmidt, Martin; Thewes, Ulrich; Thies, Carsten; Tscharntke, Teja (2004). "Aphid suppression in mulched cereals". Entomologia Experimentalis et Applicata. 113 (2): 87–93. doi:10.1111/j.0013-8703.2004.00205.x. S2CID 85070615.
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  16. ^ Dictionary of Ichthyology; Brian W. Coad and Don E. McAllister Archived 2009-12-06 at the Wayback Machine at ww.briancoad.com
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  18. ^ Grimaldi, David A. (2018-10-24). "Basal Cyclorrhapha in amber from the Cretaceous and Tertiary (Insecta: Diptera), and their relationships: Brachycera in Cretaceous amber Part IX". Bulletin of the American Museum of Natural History. 423 (423): 1–97. doi:10.1206/0003-0090-423.1.1. ISSN 0003-0090. S2CID 91679754.
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  20. ^ Thompson, F. Christian (August 19, 1999). "Flower Flies". The Diptera Site. United States Department of Agriculture. Archived from the original on December 11, 2009. Retrieved December 11, 2009.
  21. ^ Philip J. Scholl; E. Paul Catts; Gary R. Mullen (2009). "Myiasis (Muscoidea, Oestroidea)". In Gary Mullen; Gary Richard Mullen; Lance Durden (eds.). Medical and Veterinary Entomology (2nd ed.). Academic Press. pp. 309–338. ISBN 978-0-12-372500-4.
  22. ^ Laura Smith. "Syrphidae, hoverflies". bumblebee.org.
  23. ^ a b Larson, B.M.H.; Kevan, P.G.; Inouye, D. W. (2001). "Flies and flowers: taxonomic diversity of anthophiles and pollinators". Canadian Entomologist. 133 (4): 439–465. doi:10.4039/ent133439-4. S2CID 55767580.
  24. ^ Van Der Kooi, C. J.; Pen, I.; Staal, M.; Stavenga, D. G.; Elzenga, J. T. M. (2015). "Competition for pollinators and intra-communal spectral dissimilarity of flowers". Plant Biology. 18 (1): 56–62. doi:10.1111/plb.12328. PMID 25754608.
  25. ^ Haslett, J.R. (1989). "Interpreting patterns of resource utilization: randomness and selectivity in pollen feeding by adult hoverflies". Oecologia. 78 (4): 433–442. Bibcode:1989Oecol..78..433H. doi:10.1007/bf00378732. PMID 28312171. S2CID 9178645.
  26. ^ Sajjad, Asif; Saeed, Shafqat (2010). "Floral host plant range of syrphid flies (Syrphidae: Diptera) under natural conditions in southern punjab, Pakistan". Pakistan Journal of Biology. 42 (2): 1187–1200.
  27. ^ Primante, Clara; Dotterl, Stefan (2010). "A syrphid fly uses olfactory cues to find a non-yellow flower". Journal of Chemical Ecology. 36 (11): 1207–1210. doi:10.1007/s10886-010-9871-6. PMID 20924654. S2CID 23245484.
  28. ^ Campbell, Alistair, J.; Biesmeijer, J. C.; Varma, V.; Wakers, F. L. (2012). "Realising multiple ecosystem services based on the response of three beneficial insect groups to floral traits and trait diversity". Basic and Applied Ecology. 13 (4): 363–370. doi:10.1016/j.baae.2012.04.003.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  29. ^ Stokl, Johannes; Brodmann; Dafni; Ayasse; Hansson (2011). "Smells like aphids: orchid flowers mimic aphid alarm pheromones to attract hoverflies for pollination". Proc. R. Soc. B. 278 (1709): 1216–1222. doi:10.1098/rspb.2010.1770. PMC 3049078. PMID 20943694.
  30. ^ Shi, J.; Luo, Y.B.; Ran, J.C.; Liu, Z.J.; Zhou, Q. (2009). "Pollination by deceit in Paphiopedilum barbigerum (Orchidaceae): a staminode exploits innate colour preferences of hoverflies (Syrphidae)". Plant Biology. 11 (1): 17–28. doi:10.1111/j.1438-8677.2008.00120.x. PMID 19121110.
  31. ^ Ben-Issa, R., Gomez, L., & Gautier, H. (2017). Companion Plants for Aphid Pest Management. Insects, 8(4), 112. https://doi.org/10.3390/insects8040112
  32. ^ Rodriguez-Saona, C., Kaplan, I., Braasch, J., Chinnasamy, D., & Williams, L. (2011). Field responses of predaceous arthropods to methyl salicylate: A meta-analysis and case study in cranberries. Biological Control, 59(2), 394-303. https://doi.org/10.1016/j.biocontrol.2011.06.017
  33. ^ Sjöberg, Fredrik (2014). The Fly Trap. Particular Books. p. 197. ISBN 978-1-84614-776-0.
  34. ^ Barkham, Patrick (14 June 2014). "Fredrik Sjöberg: 'I realised I had to write my book for people not interested in flies'". The Guardian. Retrieved 15 March 2015.

Species lists