Sepedon armipes
Loew, 1859
marsh fly
Sepedon armipes is a North American of marsh fly in the Sciomyzidae, commonly known as snail-killing flies. Like other members of its , its larvae are aquatic of pulmonate snails. The species exhibits early-season activity, with observed active as early as February.
Pronunciation
How to pronounce Sepedon armipes: /ˈsɛp.ɪ.dɒn ˈɑr.mɪˌpɛs/
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Identification
Males of Sepedon armipes possess diagnostic hind leg modifications: the tibia is bowed in shape, and the hind is swollen and armed with teeth—features used to grasp females during mating. These traits distinguish males from females and from other Sepedon . General body form is elongate and slender with a concave and projecting . Specific distinguishing characters from are not documented in available sources.
Habitat
Aquatic and semi-aquatic environments including pond margins, stream and river banks, drainage ditches, and swampy areas. may include temporary water courses. are found near emergent vegetation where females deposit .
Distribution
North America. Specific range boundaries within North America are not documented in available sources.
Seasonality
are active in early spring; observations document activity as early as February. Adults overwinter.
Diet
Larvae are of aquatic pulmonate snails (air-breathing mollusks lacking an ). Larvae consume 8–50 snails individually during development, with smaller snails taken by early instars and larger snails by third-instar larvae. diet is not documented.
Life Cycle
are deposited in small masses on emergent vegetation. Larvae develop through three instars, all predatory on aquatic snails. Larvae respire at the water surface using surrounded by water- hairs. Mature larvae pupate within boat-shaped, capsule-like that float among organic matter at water margins. Pupal duration is not documented. emerge from puparia and overwinter.
Behavior
Larvae hunt snails just beneath the water surface. They attack snails lacking an (protective shell plate). Larvae risk suffocation from snail mucous defense secretions and entanglement of respiratory hairs in snail . Males use modified hind legs to grasp females during courtship and mating.
Ecological Role
of aquatic pulmonate snails. Potential biocontrol agent for snail intermediate of schistosomes and liver flukes, though field trials have yielded mixed results.
Human Relevance
Investigated as a potential agent for aquatic snails that affecting humans (schistosomes) and livestock (liver flukes).
Similar Taxa
- Sepedon scapularisBoth are North American Sepedon with similar larval and ; distinguished by male genitalic and leg characters per species group classification
- Other Sepedon speciesTwenty recognized in North America; distinguished by male hind leg modifications (femoral teeth, tibial bowing) and species group characteristics per Knutson and Orth (2001)