Eristalis

Latreille, 1804

Drone Flies, Droneflies

Species Guides

17

Eristalis is a large of hoverflies ( Syrphidae) comprising approximately 99 . are commonly called drone flies due to their resemblance to honeybee drones, a form of that provides protection from . The larvae, known as rat-tailed maggots, are aquatic and possess an extendable breathing siphon that allows them to inhabit oxygen-depleted environments such as stagnant water, sewage, and decomposing organic matter. Adults are important , with some species proposed as managed alternatives to honey bees for agricultural pollination.

Eristalis tenax by (c) Drepanostoma, some rights reserved (CC BY), uploaded by Drepanostoma. Used under a CC-BY license.Eristalis brousii by (c) Thilina Hettiarachchi, some rights reserved (CC BY), uploaded by Thilina Hettiarachchi. Used under a CC-BY license.Eristalis brousii by (c) Syd Cannings, some rights reserved (CC BY), uploaded by Syd Cannings. Used under a CC-BY license.

Pronunciation

How to pronounce Eristalis: //ɛˈrɪstəlɪs//

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

Identification

can be distinguished from bees by possessing only one pair of wings (bees have two pairs) and the presence of . Within Syrphidae, Eristalis is defined by the combination of: sinuate R2+3 and R4+5 , r1, basolateral setose patch on metafemur, bare triangular portion of anepimeron, pilose katepimeron, and bare meron posteroventrally. Larvae are immediately recognizable by the extremely long, extendable breathing siphon; the length of this siphon varies among , with Eristalis having among the longest. -level identification of larvae relies on (shape of clear area and arrangement of ) and pupal spiracle characteristics.

Images

Habitat

Larvae inhabit aquatic or semi-aquatic environments with low oxygen levels: stagnant pools, sewage, manure lagoons, putrid water, moist excrement, wet mud, and moist rotting vegetation. are found in diverse terrestrial including gardens, agricultural fields, meadows, and landscapes with flowering plants. Some overwinter in sheltered locations such as caves, rocky pockets, and crannies around cave mouths.

Distribution

distribution. Eristalis tenax, the most common and widespread , is native to Europe and has been introduced to North America, where it is now established across the entire continent. Present on every continent except Antarctica. Other species have more restricted ranges, with the as a whole occurring across Europe, Asia, North America, and other regions.

Seasonality

Multiple per year in favorable conditions. are active during warmer months. Some exhibit migratory , with individuals moving south in autumn to grounds around the Mediterranean and beyond, returning north in spring. Overwintering occurs in protected locations such as caves and rocky shelters during winter months.

Diet

feed on pollen and nectar, consuming pollen as a protein source for development and nectar as an energy source. They show particular affinity for members of the aster (Asteraceae) including daisies, zinnias, and asters. Larvae are saprophagous, filtering bacteria and other microbes from organic matter in decomposing substrates.

Life Cycle

Complete with four stages: , larva, pupa, . Eggs are laid on decaying organic matter in aquatic or semi-aquatic . Larvae develop through three instars in oxygen-depleted environments, breathing through the extendable siphon. Mature larvae seek dry land to pupate. Development time varies; some can complete multiple per year. occurs in a hard . Adults emerge to mate and feed on floral resources. Some species can be readily reared in laboratory conditions.

Behavior

are capable of hovering and rapid pursuit of targets. Male E. tenax pursue artificial and biological targets during territorial or courtship interactions, with pursuit consisting of two stages: initial rapid interception at high speed, followed by shadowing behavior where forward speed correlates with target speed. Adults are tetrachromats with strong color differentiation and preferences toward yellow flower colors. Larvae exhibit a distinctive behavior of hanging upside down underwater and crawling along the underside of the water meniscus while writhing, possibly to dislodge bacteria from body spines. The siphon rotates and retracts as a telescoping mechanism.

Ecological Role

function as for wildflowers and crops, including Brassica rapa, Allium cepa, Capsicum annuum, Actinidia deliciosa, and Malus domestica. They may act as keystone pollinators in some systems, particularly on islands where bees are absent. Larvae contribute to nutrient cycling by decomposing organic waste in aquatic environments. Long-distance capability facilitates between unconnected plant . May serve as mechanical for affecting bees, such as Crithidia bombi.

Human Relevance

Positive: Important for agriculture; proposed as managed alternatives to honey bees for crop pollination due to abundance, wide distribution, range, behavioral plasticity, and high reproductive success. Readily reared in laboratory conditions. Negative: Larvae may contaminate livestock feed and cause electrical short-circuits when mass congregations seek dry sites. Rare cause of accidental myiasis in humans and other mammals, including intestinal and urinary myiasis, with including abdominal pain and diarrhea. Larvae can survive gastric fluids upon ingestion. Human associated with poor . Toxicological research subject for studying neonicotinoid effects on non-target pollinators.

Similar Taxa

  • EristalinusFormerly included in Eristalis; distinguished by different larval preferences and patterns.
  • MeromacrusMember of subtribe Eristalina with Eristalis; separated based on morphological refinements of wing venation and body structure.
  • PalpadaRelated in subtribe Eristalina; occupies different with distinct larval preferences.
  • HelophilusClosely related in subtribe Eristalina; larvae often found in similar but with morphological differences in siphon structure and coloration patterns.
  • Apis mellifera (honey bee) Eristalis are Batesian mimics of drones; distinguished by single pair of wings, , and dipteran structure including large and short .

Misconceptions

Frequently misidentified as bees in popular media and photography due to strong morphological resemblance; the 'drone fly' directly references this mimicry. Biblical accounts of 'bees' spontaneously appearing from rotting carcasses may actually refer to drone flies and their rat-tailed maggot larvae, which thrive in decomposing animal matter.

More Details

Taxonomic Gender

The grammatical gender of Eristalis was disputed for two centuries, considered masculine by some authorities and feminine by others. In 2006, the International Commission on Zoological officially ruled the name to be of feminine gender, based on its Latin form referring to an unknown precious stone.

Migration Biology

Eristalis hoverflies utilize a mixed strategy of and residency. Some individuals migrate south to escape harsh winters, while others remain to exploit early-season resources if winters are mild. This strategy ensures survival across variable climatic conditions.

Antibacterial Adaptations

Larval nanopillars represent a novel physical defense against bacterial , with potential applications in medical fields where biofilm prevention is critical, such as ophthalmology and surgical instrument design.

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Sources and further reading