Eristalis hirta

Distinguished from similar Eristalis species by the black tarsi (except yellow middle leg basitarsi), combined with the specific pattern of yellow on the legs and abdomen. The prominent light yellow posterior marginal bands on abdominal segments 2–4 are unusually conspicuous. The broad face and frons in females is a notable sexual dimorphism. The black-footed common name refers to the predominantly black tarsi. Separation from Eristalis tenax requires examination of leg coloration: E. hirta has black tarsi with only the middle basitarsi yellow, whereas E. tenax typically shows more extensive yellow on the tarsi.

Adults measure 10–15 mm in length. The frons is shiny black with light brownish yellow pile; in females, the face and frons are unusually broad. Facial pile is light brownish yellow except for the shiny black facial stripe (tubercle) and cheeks. Antennae are very dark brownish black with a slightly plumose arista basally. Eyes are contiguous only in males. The thorax is dark, shiny brownish black with yellowish pile; the scutellum is lighter brownish and shiny, with pale yellow pile on the pleurae. Legs are black and yellow: front and middle femora are black with pale yellow apices; hind femur bases and apices are yellow. Front and hind tibiae are black with basal half or more pale yellow; middle tibia is mostly pale yellow. Tarsi are all black except the middle leg basitarsi, which are yellow. The abdomen is black with yellow bands and spots: segment 2 has large, sharply marked yellow-orange spots on the sides, widely separated by opaque black medially; segments 3 and 4 are shiny black with prominent light yellow posterior marginal bands. Wings are hyaline or very faintly infuscated in the middle and anterior half; pterostigma is small. Veination includes a spurious vein, looping of R4+5 into r4+5, and closed cell r2+3.

Raised bogs, ditches, and temporary pools. Larval development occurs in aquatic or semi-aquatic environments with organic matter. Adults are commonly found on and around flowers.

Western North America and Northern Europe. GBIF records confirm presence in Norway and Sweden.

Adults feed on nectar for energy and pollen as a protein source for egg development. Larvae are aquatic filter-feeders, consuming bacteria and other microbes from organic matter in the water.

Larvae are of the rat-tailed type, possessing an elongated posterior siphon for respiration at the water surface while feeding below. This siphon allows larvae to inhabit low-oxygen environments such as standing water with decaying organic matter. Larvae filter-feed on microorganisms. Mature larvae seek dry land to pupate; the pupal capsule is hard and mouse-shaped. Adults emerge to visit flowers for feeding and reproduction. Some Eristalis populations have been observed overwintering in sheltered locations such as cave mouths, though this specific behavior has not been explicitly documented for E. hirta.

Adults exhibit hovering flight typical of syrphid flies. They are important pollinators, frequently visiting flowers to obtain nectar and pollen. The species exhibits Batesian mimicry of stinging bees and wasps, which provides protection from visually hunting predators.

Adults serve as pollinators of flowering plants. Larvae contribute to nutrient cycling in aquatic habitats through filter-feeding on organic matter and microorganisms. The species provides a food source for various predators including insectivorous birds and other animals.

Adults are beneficial as pollinators in gardens and agricultural landscapes. Larvae may occasionally be encountered in water features or containers with organic debris. No significant negative impacts are documented, though related Eristalis species can rarely cause myiasis if ingested; this has not been specifically reported for E. hirta.

• Eristalis tenaxSimilar bee-mimic appearance, but E. tenax has more extensive yellow on tarsi and different abdominal pattern; cosmopolitan distribution versus Western North American and Northern European range of E. hirta.
• Eristalis arbustorumOverlapping range in Europe; distinguished by leg coloration and abdominal pattern details.

• syrphidae
• hoverfly
• drone fly
• bee mimic
• rat-tailed maggot
• pollinator
• aquatic larva
• western north america
• northern europe
• bog habitat

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
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